Fabricating high-performance, binder-free biomaterials from microalgae grown during wastewater treatment is an opportunity in sustainable materials. However, the impact of strain morphology and mechanical preprocessing on material properties remains largely uncharacterized. This study investigates binder-free biomaterials fabricated from wastewater-grown, filamentous Tribonema minus and food-grade, unicellular Chlorella vulgaris. The impact of three mechanical comminution methods (ball mill, mortar-and-pestle, and speed mixer) on the mechanical properties is evaluated. The results demonstrate that feedstock morphology and processing are critical, interacting factors. Under gentle comminution (mortar-and-pestle), filamentous Tribonema biomaterials exhibit significantly higher flexural modulus and strength than unicellular Chlorella. Conversely, high-shear speed mixing diminishes Tribonema's structural advantage while enhancing Chlorella's particle packing, leading to a convergence in mechanical properties. All final biomaterials exhibit near-hydrophobic surfaces (contact angles > 85°). This research validates that non-food-competing wastewater algae can be transformed into high-performance biomaterials, yielding materials with densities of ≈1.0–1.1 g/cm3 and flexural moduli ranging from ≈0.3 to 1.0 GPa.
\nAcoustic waves play a crucial role in various applications, including medical imaging, non-destructive testing, and sonar systems. One of the significant challenges in these applications is impedance matching, which is essential for minimizing reflections and maximizing the transfer of acoustic energy between different media. Acoustic metamaterials offer a promising solution to this challenge. In addition to impedance control, gradient stiffness can enhance structural efficiency and enable spatial control of wave propagation, making it a valuable feature in acoustic metamaterial design. In this paper, we present our developed computational method to design 3D stiffness gradient acoustic metamaterials for impedance matching. The key steps in our approach include generating initial designs using a periodic covariance function to provide unit cells that are both periodic on the boundaries and randomly formed inside the unit cell. Furthermore, we integrated manufacturing constraints into the design process, ensuring that the structures are interconnected for fabrication. We propose two computational optimization algorithms: GenUnit, based on a non-dominated sorting genetic algorithm (NSGA-II), and MLMatch, which leverages differentiable machine learning. The two approaches are not separate contributions but complementary components of a unified framework. GenUnit requires no training data and directly interfaces with physics-based simulations, making it highly accurate but slower for large-scale exploration. In contrast, MLMatch is data-hungry during training but, once trained, enables near-instantaneous inference and broad design-space coverage. Together, they form a hybrid strategy: MLMatch rapidly explores the global design space, and GenUnit provides local refinement with high-fidelity accuracy. This balance between training cost, inference time, and precision is the motivation for including both methods in the same study. We applied this dual-algorithm framework to generate two metallic-based metamaterial designs that match the acoustic impedance of water while exhibiting a controlled gradient in stiffness (from stiff to soft). The stiffness gradient is particularly advantageous in applications where one side of the structure must interface with soft or sensitive surfaces, such as human tissue or delicate components. This work paves the way for improved materials in various acoustic applications, particularly in ultrasound devices, by providing better impedance matching and thereby improving the efficiency of acoustic energy transfer.
", "doi": "10.1016/j.cma.2025.118571", "issn": "0045-7825", "publisher": "Elsevier", "publication": "Computer Methods in Applied Mechanics and Engineering", "publication_date": "2026-02-01", "volume": "449", "pages": "118571" }, { "id": "authors:0pdgv-qgh63", "collection": "authors", "collection_id": "0pdgv-qgh63", "cite_using_url": "https://authors.library.caltech.edu/records/0pdgv-qgh63", "type": "article", "title": "Abnormal crack coalescence and ductility in graphene", "author": [ { "family_name": "Jin", "given_name": "Suyeong", "orcid": "0000-0002-5627-636X" }, { "family_name": "Hong", "given_name": "Jung-Wuk", "orcid": "0000-0002-5438-1764" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Fonseca", "given_name": "Alexandre F.", "orcid": "0000-0001-8413-9744" } ], "abstract": "Crack coalescence is a critical component in the study of mechanical resistance and the stability of materials. In the particular case of graphene, despite the extensive investigation of the formation and behavior of individual cracks in graphene, the study of crack coalescence within its structure remains unexplored. In this study, we investigate the interaction between two preexisting cracks and their effect on the mechanical properties of graphene using molecular dynamics simulations. The behavior of zigzag and armchair graphene structures with cracks separated by distances ( W gap ) is analyzed under tensile loading. The findings reveal that crack coalescence, defined as the formation of a new crack from two existing crack tips, occurs for lower values of the distance between cracks, W gap , resulting in a decline in the strength of structures. As W gap increases, the stress\u2013strain curves shift upward, with the peak stress rising in the absence of crack coalescence. The effective stress intensity factor formulated in this study exhibits a clear upward trend with increasing W gap . Furthermore, an increase in W gap induces a transition in fracture behavior from crack coalescence to independent propagation with intercrack undulation. This shift in fracture behavior demonstrates a brittle-to-ductile transition, as evidenced by increased energy absorption and delayed failure. A design guideline for the initial crack geometry is suggested by correlating peak stress with the W gap , within a certain range. The findings offer insights into the fracture mechanics of graphene, emphasizing the impact of crack interaction and geometry on strength. This provides design guidelines for graphene-based structures with enhanced mechanical performance.", "doi": "10.1016/j.ijmecsci.2025.111025", "issn": "0020-7403", "publisher": "Elsevier", "publication": "International Journal of Mechanical Sciences", "publication_date": "2026-01", "volume": "309", "pages": "111025" }, { "id": "authors:eyyxm-0hz95", "collection": "authors", "collection_id": "eyyxm-0hz95", "cite_using_url": "https://authors.library.caltech.edu/records/eyyxm-0hz95", "type": "article", "title": "3D nanolithography with metalens arrays and spatially adaptive illumination", "author": [ { "family_name": "Gu", "given_name": "Songyun", "orcid": "0000-0002-9847-6685" }, { "family_name": "Mao", "given_name": "Chenkai" }, { "family_name": "Guell Izard", "given_name": "Anna", "orcid": "0000-0002-4416-7609" }, { "family_name": "Sadana", "given_name": "Sarvesh", "orcid": "0009-0001-0135-9651" }, { "family_name": "Terrel-Perez", "given_name": "Dongping" }, { "family_name": "Mettry-Yassa", "given_name": "Magi", "orcid": "0000-0001-5208-5032" }, { "family_name": "Choi", "given_name": "Wonjin" }, { "family_name": "Zhou", "given_name": "Wenjie", "orcid": "0000-0002-7626-4032", "clpid": "Zhou-Wenjie" }, { "family_name": "Yan", "given_name": "Hujie", "orcid": "0009-0002-9211-0524", "clpid": "Yan-Hujie" }, { "family_name": "Zhou", "given_name": "Ziran", "orcid": "0009-0008-9327-3505", "clpid": "Zhou-Ziran" }, { "family_name": "Massey", "given_name": "Travis" }, { "family_name": "Abelson", "given_name": "Alex" }, { "family_name": "Zhou", "given_name": "You" }, { "family_name": "Huang", "given_name": "Sijia" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Tumkur", "given_name": "Thejaswi Umanath", "orcid": "0000-0002-0355-3423" }, { "family_name": "Fan", "given_name": "Jonathan A.", "orcid": "0000-0001-9816-9979" }, { "family_name": "Xia", "given_name": "Xiaoxing", "orcid": "0000-0003-1255-3289" } ], "abstract": "The growing demand for advanced materials, miniaturized devices and integrated microsystems calls for the reliable fabrication of complex, multiscale, three-dimensional (3D) architectures, a need increasingly addressed through light-based and laser-based processes. However, owing to the field-of-view (FOV) limitations of conventional imaging optics, existing 3D laser nanofabrication techniques face fundamental challenges in throughput, proximity error and stitching defects on the path to scaling. Here we present a scalable 3D nanofabrication platform that uses a metalens-generated focal spot array to parallelize two-photon lithography (TPL) beyond centimetre-scale write field areas. Metalenses are ideally suited for producing submicron-scale focal spots for high-throughput nanolithography, as they uniquely feature large numerical apertures (NAs), immersion media compatibility and large-scale manufacturability. We experimentally demonstrate a printing system that uses a 12-cm2 metalens array to produce more than 120,000 cooperative focal spots, corresponding to a throughput exceeding 108 voxels s−1. By programmatically patterning the focal spot array using a spatial light modulator (SLM), an adaptive parallel printing strategy is developed for precise greyscale linewidth modulation and choreographed printing of semiperiodic and fully aperiodic 3D geometries. We demonstrate parallel printing of replicated microstructures (>50 M microparticles per day), centimetre-scale 3D architectures with feature sizes down to 113 nm, and photonic and mechanical metamaterials. This work demonstrates the potential of 3D nanolithography towards wafer-scale production, showing how TPL could be used at scale for applications in microelectronics, biomedicine, quantum technology and high-energy laser targets.
\nInterlocked and polycatenated material systems, consisting of discrete, nonconvex particles linked to their nearest neighbors, such as chainmail fabrics, have been shown to undergo a jamming transition that increases their rigidity under boundary compression. This rigidity transition is associated with an increase in contact number between particles. In architected materials, rigidity is described by theories such as the Maxwell criterion. In this Letter, we propose a rigidity theory for a type of interlocked material system: the torus knot tessellation. Torus knot tessellations are structured fabrics composed of particles shaped as torus knots. In these fabrics, we theoretically demonstrate that in-plane rigidity is governed by a modified Maxwell criterion, while out-of-plane rigidity is governed by a crease line criterion. These theories provide a framework for the design of rigidity of these fabrics.
", "doi": "10.1103/q4k4-x2zm", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2025-08-22", "series_number": "8", "volume": "135", "issue": "8", "pages": "088201" }, { "id": "authors:6me49-fs192", "collection": "authors", "collection_id": "6me49-fs192", "cite_using_url": "https://authors.library.caltech.edu/records/6me49-fs192", "type": "article", "title": "Frustrated domes: From planar metamaterials to load-bearing structures", "author": [ { "family_name": "Niloy", "given_name": "Imtiar", "orcid": "0000-0002-3880-1642" }, { "family_name": "Annink", "given_name": "Lucas" }, { "family_name": "Silier", "given_name": "Olivine", "clpid": "Silier-Olivine" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472" } ], "abstract": "We show that non-periodic, planar metamaterials can be turned into pop-up dome structures that are up-scalable and load-bearing. We do so by introducing a pin-jointed variation of such metamaterials. We illustrate the pop-up mechanics of these structures – dominated by the non-periodicity-induced frustration of a mechanism motion – via numerical simulations and experiments. We then show that joining together boundary nodes leads to self-standing domes that can bear significant loads, at least 20 times their own weight. Finally, we show that our idea can be easily scaled up to the meter-scale, and we illustrate that one can play around with the geometrical shape of the structural elements to obtain different pop-up shapes. Our work shows how metamaterials-related ideas that work at the tabletop-scale can be turned into concepts for innovative shape-morphing, load-bearing structures.
", "doi": "10.1016/j.eml.2025.102352", "issn": "2352-4316", "publisher": "Elsevier", "publication": "Extreme Mechanics Letters", "publication_date": "2025-08", "volume": "78", "pages": "102352" }, { "id": "authors:y8pg9-eqv46", "collection": "authors", "collection_id": "y8pg9-eqv46", "cite_using_url": "https://authors.library.caltech.edu/records/y8pg9-eqv46", "type": "article", "title": "A bright future for topological acoustics", "author": [ { "family_name": "Al\u00f9", "given_name": "Andrea", "orcid": "0000-0002-4297-5274" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Deymier", "given_name": "Pierre" }, { "family_name": "Ruzzene", "given_name": "Massimo", "orcid": "0000-0002-1502-2160" } ], "abstract": "Topological physics has been driving exciting progress in the area of condensed matter physics, with findings that have recently spilled over into the field of metamaterials research inspiring the design of structured materials that can govern in new ways the flow of light and sound. While so far these advances have been driven by fundamental curiosity-driven explorations, without a focused interest on their technological implications, opportunities to translate these findings into applied research have started to emerge, in particular in the context of sound control. Our team has been leading a highly collaborative research effort on advancing the field of topological acoustics, dubbed 'New Frontiers of Sound' and connecting it to technological opportunities for computing, communications, energy and sensing. In this comment, we outline our vision towards the future of topological sound, and its translation towards industry-relevant functionalities and operations based on extreme control of acoustic and phononic waves.
", "doi": "10.1038/s41467-025-61380-2", "pmcid": "PMC12217221", "issn": "2041-1723", "publisher": "Nature Publishing Group", "publication": "Nature Communications", "publication_date": "2025-07-01", "series_number": "1", "volume": "16", "issue": "1", "pages": "5680" }, { "id": "authors:vvr1n-ee135", "collection": "authors", "collection_id": "vvr1n-ee135", "cite_using_url": "https://authors.library.caltech.edu/records/vvr1n-ee135", "type": "article", "title": "Graph-based design of irregular metamaterials", "author": [ { "family_name": "Karimi Mahabadi", "given_name": "Rayehe", "orcid": "0000-0001-5177-635X" }, { "family_name": "Chen", "given_name": "Zhi", "orcid": "0000-0003-1993-5749" }, { "family_name": "Ogren", "given_name": "Alexander C.", "orcid": "0000-0002-7277-0069", "clpid": "Ogren-Alexander-C" }, { "family_name": "Zhang", "given_name": "Han", "orcid": "0000-0002-7522-8101" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Rudin", "given_name": "Cynthia", "orcid": "0000-0003-4283-2780" }, { "family_name": "Brinson", "given_name": "L. Catherine", "orcid": "0000-0003-2551-1563" } ], "abstract": "In the field of metamaterial research, irregular structures offer a novel and less conventional approach compared to traditional periodic designs. Designing irregular metamaterials is challenging when it comes to ensuring interconnectivity, which is essential for manufacturability. This study introduces an innovative framework for generating irregular metamaterials using graph algorithms, ensuring connectivity and adaptability across various base shapes, including cylinders, triangles, pyramids, and cubes. By employing graph algorithms, our framework enhances the intuitiveness and efficiency of design representation and manipulation, streamlining the design process. The framework generates families of designs that exhibit a wide range of property magnitudes that can be adjusted intuitively by modifying the input parameters. The rapid design process allows many designs to be generated, offering the user a multitude of solutions around the target property range. The designs can be effectively implemented in various fields and subjected to diverse analytical studies, including static, dynamic, and eigenfrequency assessments. We illustrate computational results for two key properties (stiffness and acoustic impedance), showcasing the method's effectiveness through examples ranging from rod-based to cube-based designs. The framework not only advances metamaterial research but also creates new opportunities for innovation in fields requiring customized material properties.", "doi": "10.1016/j.ijmecsci.2025.110203", "issn": "0020-7403", "publisher": "Elsevier", "publication": "International Journal of Mechanical Sciences", "publication_date": "2025-06", "volume": "295", "pages": "110203" }, { "id": "authors:ndtfy-fj247", "collection": "authors", "collection_id": "ndtfy-fj247", "cite_using_url": "https://authors.library.caltech.edu/records/ndtfy-fj247", "type": "article", "title": "A multiscale design method using interpretable machine learning for phononic materials with closely interacting scales", "author": [ { "family_name": "Bastawrous", "given_name": "Mary V.", "orcid": "0000-0003-2688-8995" }, { "family_name": "Chen", "given_name": "Zhi", "orcid": "0000-0003-1993-5749" }, { "family_name": "Ogren", "given_name": "Alexander C.", "orcid": "0000-0002-7277-0069", "clpid": "Ogren-Alexander-C" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Rudin", "given_name": "Cynthia", "orcid": "0000-0003-4283-2780" }, { "family_name": "Brinson", "given_name": "L. Catherine", "orcid": "0000-0003-2551-1563" } ], "abstract": "Manipulating the dispersive characteristics of vibrational waves is beneficial for many applications, e.g., high-precision instruments. architected hierarchical phononic materials have sparked promise tunability of elastodynamic waves and vibrations over multiple frequency ranges. In this article, hierarchical unit-cells are obtained, where features at each length scale result in a band gap within a targeted frequency range. Our novel approach, the \"hierarchical unit-cell template method,\" is an interpretable machine-learning approach that uncovers global unit-cell shape/topology patterns corresponding to predefined band-gap objectives. A scale-separation effect is observed where the coarse-scale band-gap objective is mostly unaffected by the fine-scale features despite the closeness of their length scales, thus enabling an efficient hierarchical algorithm. Moreover, the hierarchical patterns revealed are not predefined or self-similar hierarchies as common in current hierarchical phononic materials. Thus, our approach offers a flexible and efficient method for the exploration of new regions in the hierarchical design space, extracting minimal effective patterns for inverse design in applications targeting multiple frequency ranges.", "doi": "10.1016/j.cma.2025.117833", "issn": "0045-7825", "publisher": "Elsevier", "publication": "Computer Methods in Applied Mechanics and Engineering", "publication_date": "2025-05-15", "volume": "440", "pages": "117833" }, { "id": "authors:x1e5z-4zn04", "collection": "authors", "collection_id": "x1e5z-4zn04", "cite_using_url": "https://authors.library.caltech.edu/records/x1e5z-4zn04", "type": "article", "title": "Inflatable acoustic metasurfaces for tunable wave focusing", "author": [ { "family_name": "Ahn", "given_name": "Jihoon", "orcid": "0009-0006-1578-0371", "clpid": "Ahn-Jihoon" }, { "family_name": "Panahandeh-Shahraki", "given_name": "Danial", "orcid": "0000-0002-0556-9541", "clpid": "Panahandeh-Shahraki-Danial" }, { "family_name": "Kim", "given_name": "Gunho", "orcid": "0000-0003-1796-0908", "clpid": "Kim-Gunho" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Acoustic metasurfaces are two-dimensional architected materials designed to enable non-trivial control of waves, with a thickness that is either thinner than or comparable to the wavelength. However, most metasurfaces today have a fixed geometry and lack the ability to tune acoustic waves on command. This limits their ability to perform multiple functions, such as beam steering and dynamic focusing. This study introduces inflatable acoustic metasurface (IAM) lenses that enable tunable focusing. The IAMs feature two-dimensional diffractive focusing patterns embedded in a membrane that can be inflated nonplanarly through hydraulic control. It is experimentally demonstrated that inflation allows continuous focal length adjustment from \u20132.49\u03bb to +3.17\u03bb. To characterize the lens performance, changes in focal characteristics, including peak pressure, full width at half-maximum, and full length at half-maximum, are tracked at different levels of inflation. Furthermore, it is shown that IAMs can correct aberrations that occur as the angle of incidence increases in conventional planar lenses. To validate this, IAMs were tested in a concave configuration at a 20\u00b0 oblique incidence angle. The results of this study may be applicable to fields requiring continuous and real-time response in tunable focusing, including acoustic imaging and communication, ultrasound surgery, and neuromodulation.", "doi": "10.1121/10.0036567", "issn": "1520-8524", "publisher": "Acoustical Society of America (ASA)", "publication": "The Journal of the Acoustical Society of America", "publication_date": "2025-05-01", "series_number": "5", "volume": "157", "issue": "5", "pages": "3286-3295" }, { "id": "authors:kxgg6-91y28", "collection": "authors", "collection_id": "kxgg6-91y28", "cite_using_url": "https://authors.library.caltech.edu/records/kxgg6-91y28", "type": "article", "title": "Mechanical Spin Waves in a Nonlocal Discrete Magnetoelastic Lattice with Negative Group Velocity", "author": [ { "family_name": "Lee", "given_name": "Taehwa", "orcid": "0000-0001-6813-7669", "clpid": "Lee-Taehwa" }, { "family_name": "Li", "given_name": "Xiaopeng", "orcid": "0000-0001-7926-193X", "clpid": "Li-Xiaopeng" }, { "family_name": "Yu", "given_name": "Ziqi", "orcid": "0000-0001-6740-6433", "clpid": "Yu-Ziqi" }, { "family_name": "Kwon", "given_name": "Hyung\u2010Suk", "orcid": "0000-0001-8843-8354", "clpid": "Kwon-Hyung-Suk" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Structured materials can be engineered to support polarized waves generated by the rotation of the wave's displacement field, leading to spin angular momentum (SAM). This property can be leveraged to control the propagation of sound or vibrations through momentum locking or to induce nonreciprocal propagation via phonon\u2010magnon coupling. However, the physical realization of elastic metamaterials that support SAM is a challenge. Discrete lattices can be used to realize mechanical systems that support SAM associated with the rotational motion of particles as the waves propagate. Here, a discrete elastic system is demonstrated, consisting of repulsive magnets mounted on cantilevers, which exhibit elastic spin waves arising from the coupling between the longitudinal and transverse motion of the magnets. It is shown that the direct observation of spin variation can be employed to detect lattice defects. The lattice also enables unidirectional wave propagation and can transmit waves with a negative group velocity due to nonlocal interactions.
", "doi": "10.1002/apxr.202400197", "issn": "2751-1200", "publisher": "Wiley", "publication": "Advanced Physics Research", "publication_date": "2025-02-19" }, { "id": "authors:ha87a-35329", "collection": "authors", "collection_id": "ha87a-35329", "cite_using_url": "https://authors.library.caltech.edu/records/ha87a-35329", "type": "article", "title": "3D polycatenated architected materials", "author": [ { "family_name": "Zhou", "given_name": "Wenjie", "orcid": "0000-0002-7626-4032", "clpid": "Zhou-Wenjie" }, { "family_name": "Nadarajah", "given_name": "Sujeeka", "orcid": "0009-0008-7794-0347", "clpid": "Nadarajah-Sujeeka" }, { "family_name": "Li", "given_name": "Liuchi", "orcid": "0000-0002-1360-4757" }, { "family_name": "Izard", "given_name": "Anna Guell", "orcid": "0000-0002-4416-7609" }, { "family_name": "Yan", "given_name": "Hujie", "clpid": "Yan-Hujie" }, { "family_name": "Prachet", "given_name": "Aashutosh K.", "orcid": "0009-0007-0472-6895", "clpid": "Prachet-Aashutosh-K" }, { "family_name": "Patel", "given_name": "Payal", "clpid": "Patel-Payal" }, { "family_name": "Xia", "given_name": "Xiaoxing", "orcid": "0000-0003-1255-3289" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Architected materials derive their properties from the geometric arrangement of their internal structural elements. Their designs rely on continuous networks of members to control the global mechanical behavior of the bulk. In this study, we introduce a class of materials that consist of discrete concatenated rings or cage particles interlocked in three-dimensional networks, forming polycatenated architected materials (PAMs). We propose a general design framework that translates arbitrary crystalline networks into particle concatenations and geometries. In response to small external loads, PAMs behave like non-Newtonian fluids, showing both shear-thinning and shear-thickening responses, which can be controlled by their catenation topologies. At larger strains, PAMs behave like lattices and foams, with a nonlinear stress-strain relation. At microscale, we demonstrate that PAMs can change their shapes in response to applied electrostatic charges. The distinctive properties of PAMs pave the path for developing stimuli-responsive materials, energy-absorbing systems, and morphing architectures.", "doi": "10.1126/science.adr9713", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "2025-01-17", "series_number": "6731", "volume": "387", "issue": "6731", "pages": "269-277" }, { "id": "authors:9xqxj-yzk16", "collection": "authors", "collection_id": "9xqxj-yzk16", "cite_using_url": "https://authors.library.caltech.edu/records/9xqxj-yzk16", "type": "article", "title": "Multifunctional Biocomposite Materials from Chlorella vulgaris Microalgae", "author": [ { "family_name": "Kellersztein", "given_name": "Israel", "orcid": "0000-0002-8838-818X", "clpid": "Kellersztein-Israel" }, { "family_name": "Tish", "given_name": "Daniel", "orcid": "0000-0003-3776-9748" }, { "family_name": "Pederson", "given_name": "John", "orcid": "0009-0002-8500-2285", "clpid": "Pederson-John-Monroe-Jr" }, { "family_name": "Bechthold", "given_name": "Martin", "orcid": "0000-0003-2724-2301" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Extrusion 3D-printing of biopolymers and natural fiber-based biocomposites enables the fabrication of complex structures, ranging from implants' scaffolds to eco-friendly structural materials. However, conventional polymer extrusion requires high energy consumption to reduce viscosity, and natural fiber reinforcement often requires harsh chemical treatments to improve adhesion. We address these challenges by introducing a sustainable framework to fabricate natural biocomposites using Chlorella vulgaris microalgae as the matrix. Through bioink optimization and process refinement, we produced lightweight, multifunctional materials with hierarchical architectures. Infrared spectroscopy analysis reveals that hydrogen bonding plays a critical role in the binding and reinforcement of Chlorella cells by hydroxyethyl cellulose (HEC). As water content decreases, the hydrogen bonding network evolves from water-mediated interactions to direct hydrogen bonds between HEC and Chlorella, enhancing the mechanical properties. A controlled dehydration process maintains continuous microalgae morphology, preventing cracking. The resulting biocomposites exhibit a bending stiffness of 1.6 GPa and isotropic heat transfer and thermal conductivity of 0.10 W/mK at room temperature, demonstrating effective thermal insulation. These characteristics make Chlorella biocomposites promising candidates for applications requiring both structural performance and thermal insulation, offering a sustainable alternative to conventional materials in response to growing environmental demands.
", "doi": "10.1002/adma.202413618", "issn": "0935-9648", "publisher": "Wiley", "publication": "Advanced Materials", "publication_date": "2025-01", "series_number": "1", "volume": "37", "issue": "1", "pages": "2413618" }, { "id": "authors:bk4t2-b0q79", "collection": "authors", "collection_id": "bk4t2-b0q79", "cite_using_url": "https://authors.library.caltech.edu/records/bk4t2-b0q79", "type": "article", "title": "Programmable Multi\u2010Responsive Nanocellulose\u2010Based Hydrogels With Embodied Logic", "author": [ { "family_name": "Arsuffi", "given_name": "Beatriz", "orcid": "0000-0001-5081-0317", "clpid": "Arsuffi-Beatriz" }, { "family_name": "Siqueira", "given_name": "Gilberto" }, { "family_name": "Nystr\u00f6m", "given_name": "Gustav" }, { "family_name": "Titotto", "given_name": "Silvia" }, { "family_name": "Magrini", "given_name": "Tommaso", "orcid": "0000-0002-6075-7625", "clpid": "Magrini-Tommaso" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Programmable materials are desirable for a variety of functional applications that range from biomedical devices, actuators and soft robots to adaptive surfaces and deployable structures. However, current smart materials are often designed to respond to single stimuli (like temperature, humidity, or light). Here, a novel multi\u2010stimuli\u2010responsive composite is fabricated using direct ink writing (DIW) to enable programmability in both space and time and computation of logic operations. The composite hydrogels consist of double\u2010network matrices of poly(N\u2010isopropylacrylamide) (PNIPAM) or poly(acrylic acid) (PAA) and sodium alginate (SA) and are reinforced by a high content of cellulose nanocrystals (CNC) (14 wt%) and nanofibers (CNF) (1 wt%). These composites exhibit a simultaneously tunable response to external stimuli, such as temperature, pH, and ion concentration, enabling precise control over their swelling and shrinking behavior, shape, and mechanical properties over time. Bilayer hydrogel actuators are designed to display bidirectional bending in response to various stimuli scenarios. Finally, to leverage the multi\u2010responsiveness and programmability of this new composite, Boolean algebra concepts are used to design and execute NOT, YES, OR, and AND logic gates, paving the way for self\u2010actuating materials with embodied logic.
", "doi": "10.1002/adfm.202409864", "issn": "1616-301X", "publisher": "Wiley", "publication": "Advanced Functional Materials", "publication_date": "2024-09-26" }, { "id": "authors:dke83-3n708", "collection": "authors", "collection_id": "dke83-3n708", "cite_using_url": "https://authors.library.caltech.edu/records/dke83-3n708", "type": "article", "title": "Role of friction and geometry in tuning the bending stiffness of topologically interlocking materials", "author": [ { "family_name": "Lu", "given_name": "Tracy", "orcid": "0009-0004-4919-814X", "clpid": "Lu-Tracy" }, { "family_name": "Zhou", "given_name": "Ziran", "orcid": "0009-0008-9327-3505", "clpid": "Zhou-Ziran" }, { "family_name": "Bordeenithikasem", "given_name": "Punnathat", "orcid": "0000-0002-0590-2447", "clpid": "Bordeenithikasem-Punnathat" }, { "family_name": "Chung", "given_name": "Norman", "clpid": "Chung-Norman" }, { "family_name": "Franco", "given_name": "Diana Frias", "clpid": "Franco-Diana-Frias" }, { "family_name": "Andrade", "given_name": "Jos\u00e9 E.", "orcid": "0000-0003-3741-0364", "clpid": "Andrade-J-E" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In this Letter, we present the first experimental demonstration of the temporal refraction of acoustic waves in a phononic lattice. A step change in grounding stiffness results in a discontinuous change in group velocity across a so-called temporal boundary. This leads to frequency translation of incident signals, which maintain constant wavelength. We use the system to construct phononic analogs of the classical Snell and Fresnel relationships for temporal boundaries, providing evidence of temporal refraction. Last, we propose the ability to design systems to achieve tunable slow sound.
", "doi": "10.1103/physrevlett.133.077201", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2024-08-15", "series_number": "7", "volume": "133", "issue": "7", "pages": "077201" }, { "id": "authors:msh21-zx297", "collection": "authors", "collection_id": "msh21-zx297", "cite_using_url": "https://authors.library.caltech.edu/records/msh21-zx297", "type": "article", "title": "Origami engineering", "author": [ { "family_name": "Misseroni", "given_name": "Diego", "orcid": "0000-0002-7375-671X", "clpid": "Misseroni-Diego" }, { "family_name": "Pratapa", "given_name": "Phanisri P.", "orcid": "0000-0002-3563-6901", "clpid": "Pratapa-Phanisri-P" }, { "family_name": "Liu", "given_name": "Ke", "orcid": "0000-0001-9081-6334", "clpid": "Liu-Ke" }, { "family_name": "Kresling", "given_name": "Biruta", "orcid": "0000-0002-6283-1091", "clpid": "Kresling-Biruta" }, { "family_name": "Chen", "given_name": "Yan", "orcid": "0000-0002-6735-7528", "clpid": "Chen-Yan" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Paulino", "given_name": "Glaucio H.", "orcid": "0000-0002-3493-6857", "clpid": "Paulino-Glaucio-H" } ], "abstract": "Origami traces its origins to an ancient art form transforming flat thin surfaces into various complex, fabulous 3D objects. Nowadays, such transformation transcends art by offering a conceptual framework for non-destructive and scale-independent abstractions for engineering applications across diverse fields with potential impact in education, science and technology. For instance, a growing number of architected materials and structures are based on origami principles, leading to unique properties that are distinct from those previously found in either natural or engineered systems. To disseminate those concepts, this Primer provides a comprehensive overview of the major principles and elements in origami engineering, including theoretical fundamentals, simulation tools, manufacturing techniques and testing protocols that require non-standard set-ups. We highlight applications involving deployable structures, metamaterials, robotics, medical devices and programmable matter to achieve functions such as vibration control, mechanical computing and shape morphing. We identify challenges for the field, including finite rigidity, panel thickness accommodation, incompatibility with regular mechanical testing devices, manufacturing of non-developable patterns, sensitivity to imperfections and identifying the relevant physics at the scale of interest. We further envision the future of origami engineering aimed at next-generation multifunctional material and structural systems.
\nMulti-stable elements are commonly employed to design reconfigurable and adaptive structures, because they enable large and reversible shape changes in response to changing loads, while simultaneously allowing self-locking capabilities. However, existing multi-stable structures have properties that depend on their initial design and cannot be tailored post-fabrication. Here, a novel design approach is presented that combines multi-stable structures with two-way shape memory polymers. By leveraging both the one-way and two-way shape memory effect under bi-axial strain conditions, the structures can re-program their 3D shape, bear loads, and self-actuate. Results demonstrate that the structures' shape and stiffness can be tuned post-fabrication at the user's need and the multi-stability can be suppressed or activated on command. The control of multi-stability prevents undesired snapping of the structures and enables higher load-bearing capability, compared to conventional multi-stable systems. The proposed approach offers the possibility to augment the functionality of existing multi-stable concepts, showing potential for the realization of highly adaptable mechanical structures that can reversibly switch between being mono and multi-stable and that can undergo shape changes in response to a change in temperature.
\nWe provide the first experimental realization of wavenumber bandgap (q−gap) breathers. Experiments are obtained in the setting of a time-periodic phononic lattice where the model and experiment exhibit good qualitative agreement. q−gap breathers are localized in time and periodic in space, and are the counterparts to the classical breathers found in space-periodic systems. We derive an exact condition for modulation instability that leads to the opening of wavenumber bandgaps in which the q−gap breathers can arise. The q−gap breathers become more narrow and larger in amplitude as the wavenumber goes further into the bandgap. In the presence of damping, these structures acquire a nonzero, oscillating tail. The controllable temporal localization that q−gap breathers make possible has potential applications in the creation of phononic frequency combs, energy harvesting or acoustic signal processing.
", "doi": "10.1103/physrevresearch.6.023045", "issn": "2643-1564", "publisher": "American Physical Society", "publication": "Physical Review Research", "publication_date": "2024-04", "series_number": "2", "volume": "6", "issue": "2", "pages": "023045" }, { "id": "authors:h9jf2-tgw90", "collection": "authors", "collection_id": "h9jf2-tgw90", "cite_using_url": "https://authors.library.caltech.edu/records/h9jf2-tgw90", "type": "article", "title": "From Basic Principles of Protein\u2013Polysaccharide Association to the Rational Design of Thermally Sensitive Materials", "author": [ { "family_name": "Rosenberg", "given_name": "Asaf", "clpid": "Rosenberg-Asaf" }, { "family_name": "Solomonov", "given_name": "Aleksei", "orcid": "0000-0002-4582-3102", "clpid": "Solomonov-Aleksei" }, { "family_name": "Cohen", "given_name": "Hagai", "orcid": "0000-0001-8488-0727", "clpid": "Cohen-Hagai" }, { "family_name": "Eliaz", "given_name": "Dror", "orcid": "0000-0001-9444-9578", "clpid": "Eliaz-Dror" }, { "family_name": "Kellersztein", "given_name": "Israel", "orcid": "0000-0002-8838-818X", "clpid": "Kellersztein-Israel" }, { "family_name": "Brookstein", "given_name": "Ori", "orcid": "0009-0004-1546-3961", "clpid": "Brookstein-Ori" }, { "family_name": "Kozell", "given_name": "Anna", "orcid": "0000-0001-9806-1060", "clpid": "Kozell-Anna" }, { "family_name": "Wang", "given_name": "Linghui", "orcid": "0000-0003-2492-7364", "clpid": "Wang-Linghui" }, { "family_name": "Wagner", "given_name": "Hanoch Daniel", "orcid": "0000-0002-0741-2169", "clpid": "Wagner-Hanoch-Daniel" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Shimanovich", "given_name": "Ulyana", "orcid": "0000-0003-3148-0142", "clpid": "Shimanovich-Ulyana" } ], "abstract": "Biology resolves design requirements toward functional materials by creating nanostructured composites, where individual components are combined to maximize the macroscale material performance. A major challenge in utilizing such design principles is the trade-off between the preservation of individual component properties and emerging composite functionalities. Here, polysaccharide pectin and silk fibroin were investigated in their composite form with pectin as a thermal-responsive ion conductor and fibroin with exceptional mechanical strength. We show that segregative phase separation occurs upon mixing, and within a limited compositional range, domains ∼50 nm in size are formed and distributed homogeneously so that decent matrix collective properties are established. The composite is characterized by slight conformational changes in the silk domains, sequestering the hydrogen-bonded β-sheets as well as the emergence of randomized pectin orientations. However, most dominant in the composite’s properties is the introduction of dense domain interfaces, leading to increased hydration, surface hydrophilicity, and increased strain of the composite material. Using controlled surface charging in X-ray photoelectron spectroscopy, we further demonstrate Ca ions (Ca2+) diffusion in the pectin domains, with which the fingerprints of interactions at domain interfaces are revealed. Both the thermal response and the electrical conductance were found to be strongly dependent on the degree of composite hydration. Our results provide a fundamental understanding of the role of interfacial interactions and their potential applications in the design of material properties, polysaccharide–protein composites in particular.
\nOne-dimensional topological acoustic systems offer robust signal transmission and localization in compact spaces. Here, we demonstrate the ability to control both longitudinal and transverse topological waves in a quasi-one-dimensional elastic lattice, composed of an array of repelling magnets connected to elastic cantilevers. The two different topological modes can be separately or simultaneously excited at selected frequencies. Our system enables controlled multimodal propagation and edge localization, owing to its finite size and to the design of longitudinal and transverse topological band gaps within similar frequency ranges. In addition to the robustness of the topological modes to unintentional disorder, we show that disorder can couple degrees of freedom and tailor the energy distribution between longitudinal and transverse waves. This system may enable other studies on the interactions of topological modes useful in sensing and information-processing applications.
", "doi": "10.1103/physrevapplied.21.024049", "issn": "2331-7019", "publisher": "American Physical Society", "publication": "Physical Review Applied", "publication_date": "2024-02", "series_number": "2", "volume": "21", "issue": "2", "pages": "024049" }, { "id": "authors:ch9jq-hc145", "collection": "authors", "collection_id": "ch9jq-hc145", "cite_using_url": "https://authors.library.caltech.edu/records/ch9jq-hc145", "type": "article", "title": "AI-aided geometric design of anti-infection catheters", "author": [ { "family_name": "Zhou", "given_name": "Tingtao", "orcid": "0000-0002-1766-719X", "clpid": "Zhou-Tingtao" }, { "family_name": "Wan", "given_name": "Xuan", "orcid": "0000-0002-6165-6340", "clpid": "Wan-Xuan" }, { "family_name": "Huang", "given_name": "Daniel Zhengyu", "clpid": "Huang-Daniel-Zhengyu" }, { "family_name": "Li", "given_name": "Zongyi", "orcid": "0000-0003-2081-9665", "clpid": "Li-Zongyi" }, { "family_name": "Peng", "given_name": "Zhiwei", "orcid": "0000-0002-9486-2837", "clpid": "Peng-Zhiwei" }, { "family_name": "Anandkumar", "given_name": "Anima", "orcid": "0000-0002-6974-6797", "clpid": "Anandkumar-A" }, { "family_name": "Brady", "given_name": "John F.", "orcid": "0000-0001-5817-9128", "clpid": "Brady-J-F" }, { "family_name": "Sternberg", "given_name": "Paul W.", "orcid": "0000-0002-7699-0173", "clpid": "Sternberg-P-W" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Bacteria can swim upstream in a narrow tube and pose a clinical threat of urinary tract infection to patients implanted with catheters. Coatings and structured surfaces have been proposed to repel bacteria, but no such approach thoroughly addresses the contamination problem in catheters. Here, on the basis of the physical mechanism of upstream swimming, we propose a novel geometric design, optimized by an artificial intelligence model. Using\n Escherichia coli\n , we demonstrate the anti-infection mechanism in microfluidic experiments and evaluate the effectiveness of the design in three-dimensionally printed prototype catheters under clinical flow rates. Our catheter design shows that one to two orders of magnitude improved suppression of bacterial contamination at the upstream end, potentially prolonging the in-dwelling time for catheter use and reducing the overall risk of catheter-associated urinary tract infection.", "doi": "10.1126/sciadv.adj1741", "pmcid": "PMC10776022", "issn": "2375-2548", "publisher": "American Association for the Advancement of Science", "publication": "Science Advances", "publication_date": "2024-01-05", "series_number": "1", "volume": "10", "issue": "1", "pages": "eadj1741" }, { "id": "authors:74bfm-rt051", "collection": "authors", "collection_id": "74bfm-rt051", "cite_using_url": "https://authors.library.caltech.edu/records/74bfm-rt051", "type": "article", "title": "Single-test evaluation of directional elastic properties of anisotropic structured materials", "author": [ { "family_name": "Boddapati", "given_name": "Jagannadh", "orcid": "0000-0001-8706-5963", "clpid": "Boddapati-Jagannadh" }, { "family_name": "Flaschel", "given_name": "Moritz", "orcid": "0000-0002-1365-9272", "clpid": "Flaschel-Moritz" }, { "family_name": "Kumar", "given_name": "Siddhant", "orcid": "0000-0003-1602-8641", "clpid": "Kumar-Siddhant" }, { "family_name": "De Lorenzis", "given_name": "Laura", "orcid": "0000-0003-2748-3287", "clpid": "De-Lorenzis-Laura" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "When the elastic properties of structured materials become direction-dependent, the number of their descriptors increases. For example, in two-dimensions, the anisotropic behavior of materials is described by up to 6 independent elastic stiffness parameters, as opposed to only 2 needed for isotropic materials. Such high number of parameters expands the design space of structured materials and leads to unusual phenomena, such as materials that can shear under uniaxial compression. However, an increased number of properties descriptors and the coupling between shear and normal deformations render the experimental evaluation of material properties more challenging. In this paper, we propose a methodology based on the virtual fields method to identify six separate stiffness tensor parameters of two-dimensional anisotropic structured materials using just one tension test, thus eliminating the need for multiple experiments, as it is typical in traditional methods. The approach requires no stress data and uses full-field displacement data and global force data. We show the accuracy of our method using synthetic data generated from finite element simulations as well as experimental data from additively manufactured specimens.
", "doi": "10.1016/j.jmps.2023.105471", "issn": "0022-5096", "publisher": "Elsevier", "publication": "Journal of the Mechanics and Physics of Solids", "publication_date": "2023-10-21", "pages": "105471" }, { "id": "authors:80jx6-n7n15", "collection": "authors", "collection_id": "80jx6-n7n15", "cite_using_url": "https://authors.library.caltech.edu/records/80jx6-n7n15", "type": "article", "title": "Control of Mechanical and Fracture Properties in Two\u2010Phase Materials Reinforced by Continuous, Irregular Networks", "author": [ { "family_name": "Magrini", "given_name": "Tommaso", "orcid": "0000-0002-6075-7625", "clpid": "Magrini-Tommaso" }, { "family_name": "Fox", "given_name": "Chelsea", "clpid": "Fox-Chelsea" }, { "family_name": "Wihardja", "given_name": "Adeline", "clpid": "Wihardja-Adeline" }, { "family_name": "Kolli", "given_name": "Athena", "clpid": "Kolli-Athena" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Composites with high strength and high fracture resistance are desirable for structural and protective applications. Most composites, however, suffer from poor damage tolerance and are prone to unpredictable fractures. Understanding the behavior of materials with an irregular reinforcement phase offers fundamental guidelines for tailoring their performance. Here, we study the fracture nucleation and propagation in two phase composites, as a function of the topology of their irregular microstructures. We use a stochastic algorithm to design the polymeric reinforcing network, achieving independent control of topology and geometry of the microstructure. By tuning the local connectivity of isodense tiles and their assembly into larger structures, we tailor the mechanical and fracture properties of the architected composites, at the local and global scale. Finally, combining different reinforcing networks into a spatially determined meso\u2010scale assembly, we demonstrate how the spatial propagation of fractures in architected composite materials can be designed and controlled a priori.This article is protected by copyright. All rights reserved
", "doi": "10.1002/adma.202305198", "issn": "0935-9648", "publisher": "Wiley", "publication": "Advanced Materials", "publication_date": "2023-10-16", "pages": "2305198" }, { "id": "authors:c2g17-bqs82", "collection": "authors", "collection_id": "c2g17-bqs82", "cite_using_url": "https://authors.library.caltech.edu/records/c2g17-bqs82", "type": "article", "title": "Experimental evidence of amplitude-dependent surface wave dispersion via nonlinear contact resonances", "author": [ { "family_name": "Hajarolasvadi", "given_name": "Setare", "orcid": "0000-0001-5837-5903", "clpid": "Hajarolasvadi-Setare" }, { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-Paolo" }, { "family_name": "Kim", "given_name": "Brian", "orcid": "0000-0002-2403-8703", "clpid": "Kim-Brian" }, { "family_name": "Elbanna", "given_name": "Ahmed E.", "orcid": "0000-0003-4079-2607", "clpid": "Elbanna-Ahmed-E" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In this Letter, we provide an experimental demonstration of amplitude-dependent dispersion tuning of surface acoustic waves interacting with nonlinear resonators. Leveraging the similarity between the dispersion properties of plate edge waves and surface waves propagating in a semi-infinite medium, we use a setup consisting of a plate with a periodic arrangement of bead-magnet resonators along one of its edges. Nonlinear contact between the ferromagnetic beads and magnets is exploited to realize nonlinear local resonance effects. First, we experimentally demonstrate the nonlinear softening nature and amplitude-dependent dynamics of a single bead-magnet resonator on both rigid and compliant substrates. Next, the dispersion properties of the system in the linear regime are investigated. Finally, we demonstrate how the interplay of nonlinear local resonances with plate edge waves gives rise to amplitude-dependent dispersion properties. The findings will inform the design of more versatile surface acoustic wave devices that can passively adapt to loading conditions.", "doi": "10.1063/5.0151294", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2023-08-21", "series_number": "8", "volume": "123", "issue": "8", "pages": "081704" }, { "id": "authors:v2a3f-f9350", "collection": "authors", "collection_id": "v2a3f-f9350", "cite_using_url": "https://authors.library.caltech.edu/records/v2a3f-f9350", "type": "article", "title": "Ion transport in thermally responsive pectin film", "author": [ { "family_name": "Wang", "given_name": "Linghui", "orcid": "0000-0003-2492-7364", "clpid": "Wang-Linghui" }, { "family_name": "Kim", "given_name": "Tae Hyun", "orcid": "0000-0003-3856-5325", "clpid": "Kim-Tae-Hyun" }, { "family_name": "Costanza", "given_name": "Vincenzo", "orcid": "0000-0002-2409-0632", "clpid": "Costanza-Vincenzo" }, { "family_name": "Higdon", "given_name": "Nicholas J.", "orcid": "0000-0002-5806-1151", "clpid": "Higdon-Nicholas-J" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The ionic conductivity of CaCl\u2082-crosslinked pectin was found to exhibit a record-high temperature response, suggesting its potential applications in wearable devices and infrared sensors [R. Di Giacomo et al., Sci. Rob. 2, eaai9251 (2017)]. However, little was known about its ion conduction mechanisms and the origin of its high-temperature sensitivity. In this study, we perform controlled experiments and identify calcium ions as the dominant current carriers. By analyzing infrared spectra at different temperatures, we find that the temperature response is due to changes in ion mobility, rather than variations in ion number density. We compare measurements and modeling results of nine different multivalent ions and find a positive correlation between their temperature responses and their binding energy to pectin. While these findings are fundamental in nature, they provide relevant guidance for the future design of temperature-sensitive polymers and other materials for organic electronics.
", "doi": "10.1063/5.0142020", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2023-07-10", "series_number": "2", "volume": "123", "issue": "2", "pages": "021903" }, { "id": "authors:g26yq-wvj95", "collection": "authors", "collection_id": "g26yq-wvj95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230213-466109600.16", "type": "article", "title": "Bio-inspired non self-similar hierarchical elastic metamaterials", "author": [ { "family_name": "Mazzotti", "given_name": "M.", "clpid": "Mazzotti-M" }, { "family_name": "Foehr", "given_name": "A.", "orcid": "0000-0003-0941-5424", "clpid": "Foehr-Andr\u00e9" }, { "family_name": "Bilal", "given_name": "O. R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-Osama-R" }, { "family_name": "Bergamini", "given_name": "A.", "orcid": "0000-0003-2722-3207", "clpid": "Bergamini-Andrea" }, { "family_name": "Bosia", "given_name": "F.", "orcid": "0000-0002-2886-4519", "clpid": "Bosia-Federico" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Pugno", "given_name": "N. M.", "orcid": "0000-0003-2136-2396", "clpid": "Pugno-Nicola-M" }, { "family_name": "Miniaci", "given_name": "M.", "orcid": "0000-0002-6830-3548", "clpid": "Miniaci-Marco" } ], "abstract": "Hierarchy provides unique opportunities for the design of advanced materials with superior properties that arise from architecture, rather than from constitutive material response. Contrary to the quasi-static regime, where the potential of hierarchy has been largely explored, its role in vibration mitigation and wave manipulation remains elusive.\n\nSo far, the majority of the studies concerning hierarchical elastic metamaterials have proposed a self-similar repetition of a specific unit cell at multiple scale levels, leading to the activation of the same bandgap mechanism at different frequencies. On the contrary, here, we show that by designing non self-similar hierarchical geometries allows us to create periodic structures supporting multiple, highly attenuative and broadband bandgaps involving (independently or simultaneously) different scattering mechanisms, namely, Bragg scattering, local resonance and/or inertial amplification, at different frequencies. The type of band gap mechanism is identified and discussed by examining the vibrational mode shapes and the imaginary component of the wavenumber in the dispersion diagram of the unit cell. We also experimentally confirm this by performing measurements in the lowest frequency regime on a 3D printed structure.\n\nHierarchical design strategies may find application in vibration mitigation for civil, aerospace and mechanical engineering.", "doi": "10.1016/j.ijmecsci.2022.107915", "issn": "0020-7403", "publisher": "Elsevier", "publication": "International Journal of Mechanical Sciences", "publication_date": "2023-03-01", "volume": "241", "pages": "Art. No. 107915" }, { "id": "authors:drv7e-51y81", "collection": "authors", "collection_id": "drv7e-51y81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230602-251535000.10", "type": "article", "title": "Dynamics of time-modulated, nonlinear phononic lattices", "author": [ { "family_name": "Kim", "given_name": "B. L.", "orcid": "0000-0002-2403-8703", "clpid": "Kim-Brian-L" }, { "family_name": "Chong", "given_name": "C.", "orcid": "0000-0002-4908-3252", "clpid": "Chong-Christopher" }, { "family_name": "Hajarolasvadi", "given_name": "S.", "orcid": "0000-0001-5837-5903", "clpid": "Hajarolasvadi-Setare" }, { "family_name": "Wang", "given_name": "Y.", "orcid": "0000-0003-2284-520X", "clpid": "Wang-Yifan" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The propagation of acoustic and elastic waves in time-varying, spatially homogeneous media can exhibit different phenomena when compared to traditional spatially varying, temporally homogeneous media. In the present work, the response of a one-dimensional phononic lattice with time-periodic elastic properties is studied with experimental, numerical and theoretical approaches in both linear and nonlinear regimes. The system consists of repelling magnetic masses with grounding stiffness controlled by electrical coils driven with electrical signals that vary periodically in time. For small-amplitude excitation, in agreement with linear theoretical predictions, wave-number band gaps emerge. The underlying instabilities associated to the wave-number band gaps are investigated with Floquet theory and the resulting parametric amplification is observed in both theory and experiments. In contrast to genuinely linear systems, large-amplitude responses are stabilized via the nonlinear nature of the magnetic interactions of the system, and results in a family of nonlinear time-periodic states. The bifurcation structure of the periodic states is studied. It is found the linear theory correctly predicts parameter values from which the time-periodic states bifurcate from the zero state. In the presence of an external drive, the parametric amplification induced by the wave-number band gap can lead to bounded and stable responses that are temporally quasiperiodic. Controlling the propagation of acoustic and elastic waves by balancing nonlinearity and external modulation offers a new dimension in the realization of advanced signal processing and telecommunication devices. For example, it could enable time-varying, cross-frequency operation, mode- and frequency-conversion, and signal-to-noise ratio enhancements.", "doi": "10.1103/physreve.107.034211", "issn": "2470-0045", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2023-03", "series_number": "3", "volume": "107", "issue": "3", "pages": "Art. No. 034211" }, { "id": "authors:5ejta-m6285", "collection": "authors", "collection_id": "5ejta-m6285", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230530-903877800.1", "type": "article", "title": "Flexible biomimetic block copolymer composite for temperature and long-wave infrared sensing", "author": [ { "family_name": "Kim", "given_name": "Tae Hyun", "orcid": "0000-0003-3856-5325", "clpid": "Kim-Tae-Hyun" }, { "family_name": "Zhou", "given_name": "Zhun", "clpid": "Zhou-Zhun" }, { "family_name": "Choi", "given_name": "Yeong Suk", "orcid": "0000-0002-7231-9921", "clpid": "Choi-Yeong-Suk" }, { "family_name": "Costanza", "given_name": "Vincenzo", "orcid": "0000-0002-2409-0632", "clpid": "Costanza-V" }, { "family_name": "Wang", "given_name": "Linghui", "orcid": "0000-0003-2492-7364", "clpid": "Wang-Linghui" }, { "family_name": "Bahng", "given_name": "Joong Hwan", "orcid": "0000-0003-0997-9625", "clpid": "Bahng-Joong-Hwan" }, { "family_name": "Higdon", "given_name": "Nicholas J.", "orcid": "0000-0002-5806-1151", "clpid": "Higdon-Nicholas-J" }, { "family_name": "Yun", "given_name": "Youngjun", "orcid": "0000-0002-3639-9741", "clpid": "Yun-Youngjun" }, { "family_name": "Kang", "given_name": "Hyunbum", "orcid": "0000-0001-8479-2495", "clpid": "Kang-Hyunbum" }, { "family_name": "Kim", "given_name": "Sunghan", "orcid": "0000-0001-5329-8056", "clpid": "Kim-Sunghan" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Biological compounds often provide clues to advance material designs. Replicating their molecular structure and functional motifs in artificial materials offers a blueprint for unprecedented functionalities. Here, we report a flexible biomimetic thermal sensing (BTS) polymer that is designed to emulate the ion transport dynamics of a plant cell wall component, pectin. Using a simple yet versatile synthetic procedure, we engineer the physicochemical properties of the polymer by inserting elastic fragments in a block copolymer architecture, making it flexible and stretchable. The thermal response of our flexible polymer outperforms current state-of-the-art temperature sensing materials, including vanadium oxide, by up to two orders of magnitude. Thermal sensors fabricated from these composites exhibit a sensitivity that exceeds 10 mK and operate stably between 15\u00b0 and 55\u00b0C, even under repeated mechanical deformations. We demonstrate the use of our flexible BTS polymer in two-dimensional arrays for spatiotemporal temperature mapping and broadband infrared photodetection.", "doi": "10.1126/sciadv.ade0423", "pmcid": "PMC9916982", "issn": "2375-2548", "publisher": "American Association for the Advancement of Science", "publication": "Science Advances", "publication_date": "2023-02-10", "series_number": "6", "volume": "9", "issue": "6", "pages": "eade0423" }, { "id": "authors:b9pqk-q6r14", "collection": "authors", "collection_id": "b9pqk-q6r14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230221-18374200.19", "type": "article", "title": "How to see hidden patterns in metamaterials with interpretable machine learning", "author": [ { "family_name": "Chen", "given_name": "Zhi", "orcid": "0000-0003-1993-5749", "clpid": "Chen-Zhi" }, { "family_name": "Ogren", "given_name": "Alexander", "orcid": "0000-0002-7277-0069", "clpid": "Ogren-Alexander" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Brinson", "given_name": "L. Catherine", "orcid": "0000-0003-2551-1563", "clpid": "Brinson-Lynda-Catherine" }, { "family_name": "Rudin", "given_name": "Cynthia", "orcid": "0000-0003-4283-2780", "clpid": "Rudin-Cynthia" } ], "abstract": "Machine learning models can assist with metamaterials design by approximating computationally expensive simulators or solving inverse design problems. However, past work has usually relied on black box deep neural networks, whose reasoning processes are opaque and require enormous datasets that are expensive to obtain. In this work, we develop two novel machine learning approaches to metamaterials discovery that have neither of these disadvantages. These approaches, called shape-frequency features and unit-cell templates, can discover 2D metamaterials with user-specified frequency band gaps. Our approaches provide logical rule-based conditions on metamaterial unit-cells that allow for interpretable reasoning processes, and generalize well across design spaces of different resolutions. The templates also provide design flexibility where users can almost freely design the fine resolution features of a unit-cell without affecting the user's desired band gap.", "doi": "10.1016/j.eml.2022.101895", "issn": "2352-4316", "publisher": "Elsevier", "publication": "Extreme Mechanics Letters", "publication_date": "2022-11", "volume": "57", "pages": "Art. No. 101895" }, { "id": "authors:qp83g-e1956", "collection": "authors", "collection_id": "qp83g-e1956", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210809-220327946", "type": "article", "title": "Effective continuum models for the buckling of non-periodic architected sheets that display quasi-mechanism behaviors", "author": [ { "family_name": "McMahan", "given_name": "Connor", "orcid": "0000-0001-5024-6138", "clpid": "McMahan-Connor-G" }, { "family_name": "Akerson", "given_name": "Andrew", "orcid": "0000-0002-4382-1226", "clpid": "Akerson-Andrew" }, { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-Paolo" }, { "family_name": "Audoly", "given_name": "Basile", "orcid": "0000-0002-0534-1467", "clpid": "Audoly-Basile" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In this work, we construct an effective continuum model for architected sheets that are composed of bulky tiles connected by slender elastic joints. Due to their mesostructure, these sheets feature quasi-mechanisms \u2014 low-energy local kinematic modes that are strongly favored over other deformations. In sheets with non-uniform mesostructure, kinematic incompatibilities arise between neighboring regions, causing out-of-plane buckling. The effective continuum model is based on a geometric analysis of the sheets' unit cells and their energetically favorable modes of deformation. Its major feature is the construction of a strain energy that penalizes deviations from these preferred modes of deformation. The effect of non-periodicity is entirely described through the use of spatially varying geometric parameters in the model. Our simulations capture the out-of-plane buckling that occurs in non-periodic specimens and show good agreement with experiments. While we only consider one class of quasi-mechanisms, our modeling approach could be applied to a diverse set of shape-morphing systems that are of interest to the mechanics community.", "doi": "10.1016/j.jmps.2022.104934", "issn": "0022-5096", "publisher": "Elsevier", "publication": "Journal of the Mechanics and Physics of Solids", "publication_date": "2022-09", "volume": "166", "pages": "Art. No. 104934" }, { "id": "authors:praxn-t4p84", "collection": "authors", "collection_id": "praxn-t4p84", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230602-251922000.54", "type": "article", "title": "Growth rules for irregular architected materials with programmable properties", "author": [ { "family_name": "Liu", "given_name": "Ke", "orcid": "0000-0001-9081-6334", "clpid": "Liu-Ke" }, { "family_name": "Sun", "given_name": "Rachel", "orcid": "0000-0001-6396-1720", "clpid": "Sun-Rachel" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Biomaterials display microstructures that are geometrically irregular and functionally efficient. Understanding the role of irregularity in determining material properties offers a new path to engineer materials with superior functionalities, such as imperfection insensitivity, enhanced impact absorption, and stress redirection. We uncover fundamental, probabilistic structure\u2013property relationships using a growth-inspired program that evokes the formation of stochastic architectures in natural systems. This virtual growth program imposes a set of local rules on a limited number of basic elements. It generates materials that exhibit a large variation in functional properties starting from very limited initial resources, which echoes the diversity of biological systems. We identify basic rules to control mechanical properties by independently varying the microstructure's topology and geometry in a general, graph-based representation of irregular materials.", "doi": "10.1126/science.abn1459", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "2022-08-26", "series_number": "6609", "volume": "377", "issue": "6609", "pages": "975-981" }, { "id": "authors:863ej-sck97", "collection": "authors", "collection_id": "863ej-sck97", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221010-454096500.20", "type": "article", "title": "Tunable auxetic metamaterials for simultaneous attenuation of airborne sound and elastic vibrations in all directions", "author": [ { "family_name": "Kheybari", "given_name": "Majid", "orcid": "0000-0002-4507-819X", "clpid": "Kheybari-Majid" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-Osama-R" } ], "abstract": "Through a combination of analytical, numerical, and experimental methods, we study a three-dimensional metamaterial with the ability to attenuate both airborne sound and mechanical vibrations, simultaneously, and in all directions. In addition, due to the auxetic nature of the design (i.e., having a negative Poisson's ratio), the metamaterial can shrink (or expand) in a relatively uniform manner, without buckling. We utilize an external load to cause a systematic shape change in the metamaterial and tune the attenuation frequency bands. The presented design principles can be utilized in many applications related to acoustic and elastic wave manipulation as well as acoustic devices.", "doi": "10.1063/5.0104266", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2022-08-22", "series_number": "8", "volume": "121", "issue": "8", "pages": "Art. No. 081702" }, { "id": "authors:ma6ey-9e892", "collection": "authors", "collection_id": "ma6ey-9e892", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220815-504790000", "type": "article", "title": "Mode hybridization in DNA-inspired helical metamaterials with variable centro-asymmetry", "author": [ { "family_name": "Kim", "given_name": "Gunho", "orcid": "0000-0003-1796-0908", "clpid": "Kim-Gunho" }, { "family_name": "Coimbra", "given_name": "Kaila M. Y.", "orcid": "0000-0002-7239-5035", "clpid": "Coimbra-Kaila-M-Y" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study helical acoustic metamaterials and demonstrate the ability to vary the materials' dispersion properties by controlling geometrical structure and mass distribution. By locally adding eccentric, higher density elements in the unit cells, we perturb the moment of inertia of the system and introduce centro-asymmetry. This allows controlling the degree of mode coupling and the width of subwavelength bandgaps in the dispersion relation, which are the product of enhanced local resonance hybridization. We characterize the distinct normal modes in our metamaterials using finite element simulations and analytically quantify the coupling between each mode. The evolution of acoustic bandgaps induced by the increasing level of centro-asymmetry is experimentally validated with 3D-printed structures.", "doi": "10.1063/5.0106740", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2022-08-15", "series_number": "7", "volume": "121", "issue": "7", "pages": "Art. No. 072201" }, { "id": "authors:4xm8c-sh061", "collection": "authors", "collection_id": "4xm8c-sh061", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220325-220336231", "type": "article", "title": "Epidemic management and control through risk-dependent individual contact interventions", "author": [ { "family_name": "Schneider", "given_name": "Tapio", "orcid": "0000-0001-5687-2287", "clpid": "Schneider-T" }, { "family_name": "Dunbar", "given_name": "Oliver R. A.", "orcid": "0000-0001-7374-0382", "clpid": "Dunbar-Oliver-R-A" }, { "family_name": "Wu", "given_name": "Jinlong", "orcid": "0000-0001-7438-4228", "clpid": "Wu-Jinlong" }, { "family_name": "B\u00f6ttcher", "given_name": "Lucas", "orcid": "0000-0003-1700-1897", "clpid": "B\u00f6ttcher-Lucas" }, { "family_name": "Burov", "given_name": "Dmitry", "orcid": "0000-0002-5060-6794", "clpid": "Burov-Dmitry" }, { "family_name": "Garbuno-I\u00f1igo", "given_name": "Alfredo", "orcid": "0000-0003-3279-619X", "clpid": "Garbuno-I\u00f1igo-Alfredo" }, { "family_name": "Wagner", "given_name": "Gregory L.", "orcid": "0000-0001-5317-2445", "clpid": "Wagner-Gregory-L" }, { "family_name": "Pei", "given_name": "Sen", "orcid": "0000-0002-7072-2995", "clpid": "Pei-Sen" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Ferrari", "given_name": "Raffaele", "orcid": "0000-0003-1895-4294", "clpid": "Ferrari-Raffaele" }, { "family_name": "Shaman", "given_name": "Jeffrey", "orcid": "0000-0002-7216-7809", "clpid": "Shaman-Jeffrey" } ], "abstract": "Testing, contact tracing, and isolation (TTI) is an epidemic management and control approach that is difficult to implement at scale because it relies on manual tracing of contacts. Exposure notification apps have been developed to digitally scale up TTI by harnessing contact data obtained from mobile devices; however, exposure notification apps provide users only with limited binary information when they have been directly exposed to a known infection source. Here we demonstrate a scalable improvement to TTI and exposure notification apps that uses data assimilation (DA) on a contact network. Network DA exploits diverse sources of health data together with the proximity data from mobile devices that exposure notification apps rely upon. It provides users with continuously assessed individual risks of exposure and infection, which can form the basis for targeting individual contact interventions. Simulations of the early COVID-19 epidemic in New York City are used to establish proof-of-concept. In the simulations, network DA identifies up to a factor 2 more infections than contact tracing when both harness the same contact data and diagnostic test data. This remains true even when only a relatively small fraction of the population uses network DA. When a sufficiently large fraction of the population (\u2273 75%) uses network DA and complies with individual contact interventions, targeting contact interventions with network DA reduces deaths by up to a factor 4 relative to TTI. Network DA can be implemented by expanding the computational backend of existing exposure notification apps, thus greatly enhancing their capabilities. Implemented at scale, it has the potential to precisely and effectively control future epidemics while minimizing economic disruption.", "doi": "10.1371/journal.pcbi.1010171", "pmcid": "PMC9223336", "issn": "1553-734X", "publisher": "Public Library of Science", "publication": "PLoS Computational Biology", "publication_date": "2022-06-23", "series_number": "6", "volume": "18", "issue": "6", "pages": "Art. No. e1010171" }, { "id": "authors:s7jz3-ts411", "collection": "authors", "collection_id": "s7jz3-ts411", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220428-212239375", "type": "article", "title": "Capacitive Temperature Sensing via Displacement Amplification", "author": [ { "family_name": "Taniker", "given_name": "Semih", "orcid": "0000-0003-2423-9238", "clpid": "Taniker-Semih" }, { "family_name": "Costanza", "given_name": "Vincenzo", "orcid": "0000-0002-2409-0632", "clpid": "Costanza-Vincenzo" }, { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-Paolo" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We propose the realization of capacitive temperature sensors based on the concept of displacement amplification. Our design features two high coefficient of thermal expansion (CTE) metallic layers separated by a low-CTE dielectric layer; conductive and dielectric layers are then separated by a thin air gap and glued together at a few locations. As the temperature increases, the high-CTE layer tends to expand more than the low-CTE one. Owing to the constraint to planar expansion imposed by the low-CTE layer, this results in large out-of-plane displacements of the high-CTE layer \u2013 hence the displacement amplification term. In our case, the high-CTE layer buckles and causes a reduction of the gap between conductive and dielectric layers; in turn, this results in a large change of capacitance. First, we illustrate the concept via numerical simulations. Then, we realize a low-cost prototype of such sensor by using aluminum foil as conductor, paper as dielectric, and by gluing the layers together with cyanoacrylate. Our results demonstrate the potential of this simple design as a route towards efficient and low-cost temperature sensors.", "doi": "10.1109/JSEN.2022.3169585", "issn": "1530-437X", "publisher": "IEEE", "publication": "IEEE Sensors Journal", "publication_date": "2022-06-01", "series_number": "11", "volume": "22", "issue": "11", "pages": "10388-10395" }, { "id": "authors:8jxr7-e6124", "collection": "authors", "collection_id": "8jxr7-e6124", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190918-130321479", "type": "article", "title": "Biological matrix composites from cultured plant cells", "author": [ { "family_name": "Roumeli", "given_name": "Eleftheria", "orcid": "0000-0002-2828-1428", "clpid": "Roumeli-Eleftheria" }, { "family_name": "Hendrickx", "given_name": "Rodinde", "clpid": "Hendrickx-Rodinde" }, { "family_name": "Bonanomi", "given_name": "Luca", "clpid": "Bonanomi-Luca" }, { "family_name": "Vashisth", "given_name": "Aniruddh", "orcid": "0000-0002-4740-1296", "clpid": "Vashisth-Aniruddh" }, { "family_name": "Rinaldi", "given_name": "Katherine", "orcid": "0000-0002-0746-2852", "clpid": "Rinaldi-Katherine-Z" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We present an approach to fabricate biological matrix composites made entirely from cultured plant cells. We utilize the cell's innate ability to synthesize nanofibrillar cell walls, which serve as the composite's fundamental building blocks. Following a controlled compression/dehydration process, the cells arrange into lamellar structures with hierarchical features. We demonstrate that the native cell wall nanofibrils tether adjacent cells together through fibrillar interlocking and intermolecular hydrogen bonding. These interactions facilitate intercellular adhesion and eliminate the need for other binders. Our fabrication process utilizes the entire plant cell, grown in an in vitro culture; requires no harsh chemical treatments or waste-generating extraction or selection processes; and leads to bulk biocomposites that can be produced in situ and biodegrade in soil. The final mechanical properties are comparable to commodity plastics and can be further modulated by introducing filler particles.", "doi": "10.1073/pnas.2119523119", "pmcid": "PMC9169740", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences", "publication_date": "2022-04-04", "series_number": "15", "volume": "119", "issue": "15", "pages": "Art. No. e2119523119" }, { "id": "authors:1p4q3-vmg16", "collection": "authors", "collection_id": "1p4q3-vmg16", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220323-704234000", "type": "article", "title": "Mechanical cloak via data-driven aperiodic metamaterial design", "author": [ { "family_name": "Wang", "given_name": "Liwei", "orcid": "0000-0002-2777-9718", "clpid": "Wang-Liwei" }, { "family_name": "Boddapati", "given_name": "Jagannadh", "orcid": "0000-0001-8706-5963", "clpid": "Boddapati-Jagannadh" }, { "family_name": "Liu", "given_name": "Ke", "orcid": "0000-0001-9081-6334", "clpid": "Liu-Ke" }, { "family_name": "Zhu", "given_name": "Ping", "orcid": "0000-0002-1153-0379", "clpid": "Zhu-Ping" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Chen", "given_name": "Wei", "clpid": "Chen-Wei" } ], "abstract": "Mechanical cloaks are materials engineered to manipulate the elastic response around objects to make them indistinguishable from their homogeneous surroundings. Typically, methods based on material-parameter transformations are used to design optical, thermal, and electric cloaks. However, they are not applicable in designing mechanical cloaks, since continuum-mechanics equations are not form invariant under general coordinate transformations. As a result, existing design methods for mechanical cloaks have so far been limited to a narrow selection of voids with simple shapes. To address this challenge, we present a systematic, data-driven design approach to create mechanical cloaks composed of aperiodic metamaterials using a large precomputed unit cell database. Our method is flexible to allow the design of cloaks with various boundary conditions, multiple loadings, different shapes and numbers of voids, and different homogeneous surroundings. It enables a concurrent optimization of both topology and properties distribution of the cloak. Compared to conventional fixed-shape solutions, this results in an overall better cloaking performance and offers unparalleled versatility. Experimental measurements on additively manufactured structures further confirm the validity of the proposed approach. Our research illustrates the benefits of data-driven approaches in quickly responding to new design scenarios and resolving the computational challenge associated with multiscale designs of functional structures. It could be generalized to accommodate other applications that require heterogeneous property distribution, such as soft robots and implants design.", "doi": "10.1073/pnas.2122185119", "pmcid": "PMC9060453", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2022-03-29", "series_number": "13", "volume": "119", "issue": "13", "pages": "Art. No. e2122185119" }, { "id": "authors:m0enf-hna63", "collection": "authors", "collection_id": "m0enf-hna63", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210729-194549899", "type": "article", "title": "Rayleigh wave propagation in nonlinear metasurfaces", "author": [ { "family_name": "Palermo", "given_name": "A.", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-Antonio" }, { "family_name": "Yousefzadeh", "given_name": "B.", "orcid": "0000-0002-6973-717X", "clpid": "Yousefzadeh-Behrooz" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Marzani", "given_name": "A.", "orcid": "0000-0001-7697-6729", "clpid": "Marzani-Alessandro" } ], "abstract": "We investigate the propagation of Rayleigh waves in a half-space coupled to a nonlinear metasurface. The metasurface consists of an array of nonlinear oscillators attached to the free surface of a homogeneous substrate. We describe, analytically and numerically, the effects of nonlinear interaction force and energy loss on the dispersion of Rayleigh waves. We develop closed-form expressions to predict the dispersive characteristics of nonlinear Rayleigh waves by adopting a leading-order effective medium description. In particular, we demonstrate how hardening nonlinearity reduces and eventually eliminates the linear filtering bandwidth of the metasurface. Softening nonlinearity, in contrast, induces lower and broader spectral gaps for weak to moderate strengths of nonlinearity, and narrows and eventually closes the gaps at high strengths of nonlinearity. We also observe the emergence of a spatial gap (in wavenumber) in the in-phase branch of the dispersion curves for softening nonlinearity. Finally, we investigate the interplay between nonlinearity and energy loss and discuss their combined effects on the dispersive properties of the metasurface. Our analytical results, supported by finite element simulations, demonstrate the mechanisms for achieving tunable dispersion characteristics in nonlinear metasurfaces.", "doi": "10.1016/j.jsv.2021.116599", "issn": "0022-460X", "publisher": "Elsevier", "publication": "Journal of Sound and Vibration", "publication_date": "2022-03-03", "volume": "520", "pages": "Art. No. 116599" }, { "id": "authors:m7qr1-12e11", "collection": "authors", "collection_id": "m7qr1-12e11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230725-706639000.52", "type": "article", "title": "Cell wall and cytoskeletal contributions in single cell biomechanics of Nicotiana tabacum", "author": [ { "family_name": "Ginsberg", "given_name": "Leah", "orcid": "0000-0001-9685-7014", "clpid": "Ginsberg-Leah" }, { "family_name": "McDonald", "given_name": "Robin", "clpid": "McDonald-Robin" }, { "family_name": "Lin", "given_name": "Qinchen", "clpid": "Lin-Qinchen" }, { "family_name": "Hendrickx", "given_name": "Rodinde", "orcid": "0000-0001-7161-4526", "clpid": "Hendrickx-Rodinde" }, { "family_name": "Spigolon", "given_name": "Giada", "orcid": "0000-0002-1704-8372", "clpid": "Spigolon-Giada" }, { "family_name": "Ravichandran", "given_name": "Guruswami", "orcid": "0000-0002-2912-0001", "clpid": "Ravichandran-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Roumeli", "given_name": "Eleftheria", "orcid": "0000-0002-2828-1428", "clpid": "Roumeli-Eleftheria" } ], "abstract": "Studies on the mechanics of plant cells usually focus on understanding the effects of turgor pressure and properties of the cell wall (CW). While the functional roles of the underlying cytoskeleton have been studied, the extent to which it contributes to the mechanical properties of cells is not elucidated. Here, we study the contributions of the CW, microtubules (MTs) and actin filaments (AFs), in the mechanical properties of Nicotiana tabacum cells. We use a multiscale biomechanical assay comprised of atomic force microscopy and micro-indentation in solutions that (i) remove MTs and AFs and (ii) alter osmotic pressures in the cells. To compare measurements obtained by the two mechanical tests, we develop two generative statistical models to describe the cell's behaviour using one or both datasets. Our results illustrate that MTs and AFs contribute significantly to cell stiffness and dissipated energy, while confirming the dominant role of turgor pressure.", "doi": "10.1017/qpb.2021.15", "pmcid": "PMC10097588", "issn": "2632-8828", "publisher": "Cambridge University Press", "publication": "Quantitative Plant Biology", "publication_date": "2022-01-22", "volume": "3", "pages": "e1" }, { "id": "authors:0714q-6pz23", "collection": "authors", "collection_id": "0714q-6pz23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220325-220328812", "type": "monograph", "title": "How to See Hidden Patterns in Metamaterials with Interpretable Machine Learning", "author": [ { "family_name": "Chen", "given_name": "Zhi", "clpid": "Chen-Zhi" }, { "family_name": "Ogren", "given_name": "Alexander", "clpid": "Ogren-Alexander-C" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Brinson", "given_name": "L. Catherine", "orcid": "0000-0003-2551-1563", "clpid": "Brinson-Lynda-Catherine" }, { "family_name": "Rudin", "given_name": "Cynthia", "orcid": "0000-0003-4283-2780", "clpid": "Rudin-Cynthia" } ], "abstract": "Metamaterials are composite materials with engineered geometrical micro- and meso-structures that can lead to uncommon physical properties, like negative Poisson's ratio or ultra-low shear resistance. Periodic metamaterials are composed of repeating unit-cells, and geometrical patterns within these unit-cells influence the propagation of elastic or acoustic waves and control dispersion. In this work, we develop a new interpretable, multi-resolution machine learning framework for finding patterns in the unit-cells of materials that reveal their dynamic properties. Specifically, we propose two new interpretable representations of metamaterials, called shape-frequency features and unit-cell templates. Machine learning models built using these feature classes can accurately predict dynamic material properties. These feature representations (particularly the unit-cell templates) have a useful property: they can operate on designs of higher resolutions. By learning key coarse scale patterns that can be reliably transferred to finer resolution design space via the shape-frequency features or unit-cell templates, we can almost freely design the fine resolution features of the unit-cell without changing coarse scale physics. Through this multi-resolution approach, we are able to design materials that possess target frequency ranges in which waves are allowed or disallowed to propagate (frequency bandgaps). Our approach yields major benefits: (1) unlike typical machine learning approaches to materials science, our models are interpretable, (2) our approaches leverage multi-resolution properties, and (3) our approach provides design flexibility.", "doi": "10.48550/arXiv.2111.05949", "publisher": "arXiv", "publication_date": "2021-11-10" }, { "id": "authors:24km7-q4q86", "collection": "authors", "collection_id": "24km7-q4q86", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211102-204833333", "type": "article", "title": "Poroelastic microlattices for underwater wave focusing", "author": [ { "family_name": "Kim", "given_name": "Gunho", "orcid": "0000-0003-1796-0908", "clpid": "Kim-Gunho" }, { "family_name": "Portela", "given_name": "Carlos M.", "orcid": "0000-0002-2649-4235", "clpid": "Portela-Carlos-M" }, { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-Paolo" }, { "family_name": "Palermo", "given_name": "Antonio", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-Antonio" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Metamaterials with microscale architectures, e.g., microlattices, can exhibit extreme quasi-static mechanical response and tailorable acoustic properties. When coupled with pressure waves in surrounding fluid, the dynamic behavior of microlattices in the long wavelength limit can be explained in the context of Biot's theory of poroelasticity. In this work, we exploit the elastoacoustic wave propagation within 3D-printed polymeric microlattices to incorporate a gradient of refractive index for underwater ultrasonic lensing. Experimentally and numerically derived dispersion curves allow the characterization of acoustic properties of a fluid-saturated elastic lattice. A modified Luneburg lens index profile adapted for underwater wave focusing is demonstrated via the finite element method and immersion testing, showcasing a computationally efficient poroelasticity-based design approach that enables accelerated design of acoustic wave manipulation devices. Our approach can be applied to the design of acoustic metamaterials for biomedical applications featuring focused ultrasound.", "doi": "10.1016/j.eml.2021.101499", "issn": "2352-4316", "publisher": "Elsevier", "publication": "Extreme Mechanics Letters", "publication_date": "2021-11", "volume": "49", "pages": "Art. No. 101499" }, { "id": "authors:frpdx-nqb52", "collection": "authors", "collection_id": "frpdx-nqb52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220325-220332816", "type": "monograph", "title": "Sparse metapiles for shear wave attenuation in half-spaces", "author": [ { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-Paolo" }, { "family_name": "Nunzi", "given_name": "Ilaria", "clpid": "Nunzi-Ilaria" }, { "family_name": "Calabrese", "given_name": "Andrea", "clpid": "Calabrese-Andrea" }, { "family_name": "Lenci", "given_name": "Stefano", "orcid": "0000-0003-3154-7896", "clpid": "Lenci-Stefano" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We show that shear waves traveling towards the surface of a half-space medium can be attenuated via buried one-dimensional arrays of resonators -- here called metapiles -- arranged according to sparse patterns around a site to be isolated. Our focus is on shear waves approaching the surface along a direction perpendicular to the surface itself. First, we illustrate the behavior of metapiles, both experimentally and numerically, using 3D printed resonators embedded in an acrylic plate. Then, via numerical simulations, we extend this idea to the case study of an idealized soil half-space, and elucidate the influence of various design parameters on wave attenuation. Results of this work demonstrate that significant wave attenuation can be achieved by installing sparse resonating piles around a selected site on the free surface of the medium, rather than placing resonators directly underneath that same site. This work might have implications in metamaterial-based wave attenuation applications across scales.", "doi": "10.48550/arXiv.2110.02202", "publisher": "arXiv", "publication_date": "2021-10-05" }, { "id": "authors:t74qg-92f12", "collection": "authors", "collection_id": "t74qg-92f12", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210519-124245707", "type": "article", "title": "Structured fabrics with tunable mechanical properties", "author": [ { "family_name": "Wang", "given_name": "Yifan", "orcid": "0000-0001-9965-9777", "clpid": "Wang-Yifan" }, { "family_name": "Li", "given_name": "Liuchi", "orcid": "0000-0002-1360-4757", "clpid": "Li-Liuchi" }, { "family_name": "Hofmann", "given_name": "Douglas", "orcid": "0000-0002-0872-5239", "clpid": "Hofmann-Douglas-C" }, { "family_name": "Andrade", "given_name": "Jos\u00e9 E.", "clpid": "Andrade-J-E" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Structured fabrics, such as woven sheets or chain mail armours, derive their properties both from the constitutive materials and their geometry. Their design can target desirable characteristics, such as high impact resistance, thermal regulation, or electrical conductivity. Once realized, however, the fabrics' properties are usually fixed. Here we demonstrate structured fabrics with tunable bending modulus, consisting of three-dimensional particles arranged into layered chain mails. The chain mails conform to complex shapes, but when pressure is exerted at their boundaries, the particles interlock and the chain mails jam. We show that, with small external pressure (about 93 kilopascals), the sheets become more than 25 times stiffer than in their relaxed configuration. This dramatic increase in bending resistance arises because the interlocking particles have high tensile resistance, unlike what is found for loose granular media. We use discrete-element simulations to relate the chain mail's micro-structure to macroscale properties and to interpret experimental measurements. We find that chain mails, consisting of different non-convex granular particles, undergo a jamming phase transition that is described by a characteristic power-law function akin to the behaviour of conventional convex media. Our work provides routes towards lightweight, tunable and adaptive fabrics, with potential applications in wearable exoskeletons, haptic architectures and reconfigurable medical supports.", "doi": "10.1038/s41586-021-03698-7", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2021-08-12", "series_number": "7871", "volume": "596", "issue": "7871", "pages": "238-243" }, { "id": "authors:ed6ms-7ze27", "collection": "authors", "collection_id": "ed6ms-7ze27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210716-222546164", "type": "monograph", "title": "Tuning acoustic impedance in load-bearing structures", "author": [ { "family_name": "Injeti", "given_name": "Sai Sharan", "orcid": "0000-0003-1941-9752", "clpid": "Injeti-Sai-Sharan" }, { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-Paolo" }, { "family_name": "Bhattacharya", "given_name": "Kaushik", "orcid": "0000-0003-2908-5469", "clpid": "Bhattacharya-K" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Acoustic transparency is the capability of a medium to transmit mechanical waves to adjacent media, without scattering. This characteristic can be achieved by carefully engineering the acoustic impedance of the medium -- a combination of wave speed and density, to match that of the surroundings. Owing to the strong correlation between acoustic wave speed and static stiffness, it is challenging to design acoustically transparent materials in a fluid, while maintaining their high structural rigidity. In this work, we propose a method to design architected lattices with independent control of the elastic wave speed at a chosen frequency, the mass density, and the static stiffness, along a chosen loading direction. We provide a sensitivity analysis to optimize these properties with respect to design parameters of the structure, that include localized masses at specific positions. We demonstrate the method on five different periodic, three dimensional lattices, to calculate bounds on the longitudinal wave speed as a function of their density and stiffness. We then perform experiments on 3-D printed structures, to validate our numerical simulations. The tools developed in this work can be used to design lightweight and stiff materials with optimized acoustic impedance for a plethora of applications, including ultrasound imaging, wave filtering and waveguiding.", "doi": "10.48550/arXiv.2106.10573", "publisher": "arXiv", "publication_date": "2021-06-19" }, { "id": "authors:s9asz-mrz44", "collection": "authors", "collection_id": "s9asz-mrz44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210310-140501690", "type": "article", "title": "A micromechanical-based model of stimulus responsive liquid crystal elastomers", "author": [ { "family_name": "Brighenti", "given_name": "Roberto", "orcid": "0000-0002-9273-0822", "clpid": "Brighenti-Roberto" }, { "family_name": "McMahan", "given_name": "Connor G.", "orcid": "0000-0001-5024-6138", "clpid": "McMahan-Connor-G" }, { "family_name": "Cosma", "given_name": "Mattia P.", "orcid": "0000-0002-4795-9150", "clpid": "Cosma-Mattia-P" }, { "family_name": "Kotikian", "given_name": "Arda", "orcid": "0000-0001-6655-3845", "clpid": "Kotikian-Arda" }, { "family_name": "Lewis", "given_name": "Jennifer A.", "clpid": "Lewis-Jennifer-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Stimulus responsive elastomers are advanced engineered materials that perform desired functionalities when triggered by external stimuli. Liquid crystal elastomers (LCEs) are one important example that exhibit reversible actuation when cycled above and below their nematic-to-isotropic transition temperature. Here, we propose a micromechanical-based model that is centered on the evolution of the chain distribution tensor of the LCE network. Our model, framed within the statistical model of the chain network, enables a mesoscale description of their mechanical response under an external thermal stimulus. We compare the model to prior experimental observations of the bending response of 3D printed LCE elements with controlled director alignment.", "doi": "10.1016/j.ijsolstr.2021.02.023", "issn": "0020-7683", "publisher": "Elsevier", "publication": "International Journal of Solids and Structures", "publication_date": "2021-06-01", "volume": "219-220", "pages": "92-105" }, { "id": "authors:zk9jg-rwa18", "collection": "authors", "collection_id": "zk9jg-rwa18", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210513-135353993", "type": "article", "title": "Robotic surfaces with reversible, spatiotemporal control for shape morphing and object manipulation", "author": [ { "family_name": "Liu", "given_name": "Ke", "orcid": "0000-0001-9081-6334", "clpid": "Liu-Ke" }, { "family_name": "Hacker", "given_name": "Felix", "orcid": "0000-0002-9233-4619", "clpid": "Hacker-Felix" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Continuous and controlled shape morphing is essential for soft machines to conform, grasp, and move while interacting safely with their surroundings. Shape morphing can be achieved with two-dimensional (2D) sheets that reconfigure into target 3D geometries, for example, using stimuli-responsive materials. However, most existing solutions lack the ability to reprogram their shape, face limitations on attainable geometries, or have insufficient mechanical stiffness to manipulate objects. Here, we develop a soft, robotic surface that allows for large, reprogrammable, and pliable shape morphing into smooth 3D geometries. The robotic surface consists of a layered design composed of two active networks serving as artificial muscles, one passive network serving as a skeleton, and cover scales serving as an artificial skin. The active network consists of a grid of strips made of heat-responsive liquid crystal elastomers (LCEs) containing stretchable heating coils. The magnitude and speed of contraction of the LCEs can be controlled by varying the input electric currents. The 1D contraction of the LCE strips activates in-plane and out-of-plane deformations; these deformations are both necessary to transform a flat surface into arbitrary 3D geometries. We characterize the fundamental deformation response of the layers and derive a control scheme for actuation. We demonstrate that the robotic surface provides sufficient mechanical stiffness and stability to manipulate other objects. This approach has potential to address the needs of a range of applications beyond shape changes, such as human-robot interactions and reconfigurable electronics.", "doi": "10.1126/scirobotics.abf5116", "issn": "2470-9476", "publisher": "American Association for the Advancement of Science", "publication": "Science Robotics", "publication_date": "2021-04-07", "series_number": "53", "volume": "6", "issue": "53", "pages": "Art. No. eabf5116" }, { "id": "authors:40rgs-6rb67", "collection": "authors", "collection_id": "40rgs-6rb67", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210604-142555952", "type": "monograph", "title": "Visual Vibration Tomography: Estimating Interior Material Properties from Monocular Video", "author": [ { "family_name": "Feng", "given_name": "Berthy T.", "clpid": "Feng-Berthy-T" }, { "family_name": "Ogren", "given_name": "Alexander C.", "clpid": "Ogren-Alexander-C" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Bouman", "given_name": "Katherine L.", "orcid": "0000-0003-0077-4367", "clpid": "Bouman-K-L" } ], "abstract": "An object's interior material properties, while invisible to the human eye, determine motion observed on its surface. We propose an approach that estimates heterogeneous material properties of an object from a monocular video of its surface vibrations. Specifically, we show how to estimate Young's modulus and density throughout a 3D object with known geometry. Knowledge of how these values change across the object is useful for simulating its motion and characterizing any defects. Traditional non-destructive testing approaches, which often require expensive instruments, generally estimate only homogenized material properties or simply identify the presence of defects. In contrast, our approach leverages monocular video to (1) identify image-space modes from an object's sub-pixel motion, and (2) directly infer spatially-varying Young's modulus and density values from the observed modes. We demonstrate our approach on both simulated and real videos.", "doi": "10.48550/arXiv.2104.02735", "publisher": "arXiv", "publication_date": "2021-04-06" }, { "id": "authors:cx7k5-nk418", "collection": "authors", "collection_id": "cx7k5-nk418", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210106-102302065", "type": "article", "title": "Prestrain-induced bandgap tuning in 3D-printed tensegrity-inspired lattice structures", "author": [ { "family_name": "Pajunen", "given_name": "Kirsti", "orcid": "0000-0002-5366-1190", "clpid": "Pajunen-Kirsti" }, { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-Paolo" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In this letter, we provide experimental evidence of bandgap tunability with global prestrain in additively-manufactured tensegrity-inspired lattice structures. These lattices are extremely lightweight and designed to exhibit a nonlinear compressive response that mimics that of a tensegrity structure. We fabricate them out of a stiff polymer but, owing to their peculiar design, they are compliant and remain elastic up to high levels of precompression. In turn, unlike tunable metamaterials made of soft polymers, the response of our lattices is not dominated by damping. We perform experiments on a one-dimensional lattice subject to longitudinal wave excitation and varying levels of static longitudinal precompression, and observe continuous tuning of both the wave speed and the location and width of the lowest-frequency bandgap.", "doi": "10.1016/j.eml.2021.101236", "issn": "2352-4316", "publisher": "Elsevier", "publication": "Extreme Mechanics Letters", "publication_date": "2021-04", "volume": "44", "pages": "Art. No. 101236" }, { "id": "authors:srvs5-5ct78", "collection": "authors", "collection_id": "srvs5-5ct78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210423-164902313", "type": "article", "title": "Nonlinear localized modes in two-dimensional hexagonally-packed magnetic lattices", "author": [ { "family_name": "Chong", "given_name": "Christopher", "orcid": "0000-0002-4908-3252", "clpid": "Chong-Christopher" }, { "family_name": "Wang", "given_name": "Yifan", "orcid": "0000-0003-2284-520X", "clpid": "Wang-Yifan" }, { "family_name": "Mar\u00e9chal", "given_name": "Donovan", "clpid": "Mar\u00e9chal-Donovan" }, { "family_name": "Charalampidis", "given_name": "Efstathios G.", "orcid": "0000-0002-5417-4431", "clpid": "Charalampidis-Efstathios-G" }, { "family_name": "Moler\u00f3n", "given_name": "Miguel", "clpid": "Moler\u00f3n-Miguel" }, { "family_name": "Mart\u00ednez", "given_name": "Alejandro J.", "clpid": "Mart\u00ednez-Alejandro-J" }, { "family_name": "Porter", "given_name": "Mason A.", "orcid": "0000-0002-5166-0717", "clpid": "Porter-Mason-A" }, { "family_name": "Kevrekidis", "given_name": "Panayotis G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-Panayotis-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We conduct an extensive study of nonlinear localized modes (NLMs), which are temporally periodic and spatially localized structures, in a two-dimensional array of repelling magnets. In our experiments, we arrange a lattice in a hexagonal configuration with a light-mass defect, and we harmonically drive the center of the chain with a tunable excitation frequency, amplitude, and angle. We use a damped, driven variant of a vector Fermi\u2013Pasta\u2013Ulam\u2013Tsingou lattice to model our experimental setup. Despite the idealized nature of this model, we obtain good qualitative agreement between theory and experiments for a variety of dynamical behaviors. We find that the spatial decay is direction-dependent and that drive amplitudes along fundamental displacement axes lead to nonlinear resonant peaks in frequency continuations that are similar to those that occur in one-dimensional damped, driven lattices. However, we observe numerically that driving along other directions results in asymmetric NLMs that bifurcate from the main solution branch, which consists of symmetric NLMs. We also demonstrate both experimentally and numerically that solutions that appear to be time-quasiperiodic bifurcate from the branch of symmetric time-periodic NLMs.", "doi": "10.1088/1367-2630/abdb6f", "issn": "1367-2630", "publisher": "IOP", "publication": "New Journal of Physics", "publication_date": "2021-04", "series_number": "4", "volume": "23", "issue": "4", "pages": "Art. No. 043008" }, { "id": "authors:30hr3-d3642", "collection": "authors", "collection_id": "30hr3-d3642", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201120-111506487", "type": "article", "title": "Systematic two-scale image analysis of extreme deformations in soft architectured sheets", "author": [ { "family_name": "Agnelli", "given_name": "Filippo", "clpid": "Agnelli-Filippo" }, { "family_name": "Margerit", "given_name": "Pierre", "clpid": "Margerit-Pierre" }, { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-Paolo" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Constantinescu", "given_name": "Andrei", "clpid": "Constantinescu-Andrei" } ], "abstract": "The multi-scale nature of architectured materials raises the need for advanced experimental methods suitable for the identification of their effective properties, especially when their size is finite and they undergo extreme deformations. The present work demonstrates that state-of-the art image processing methods combined with numerical and analytical models provide a comprehensive quantitative description of these solids and their global behaviour, including the influence of the boundary conditions, of the manufacturing process, and of geometric and constitutive non-linearities. To this end, an adapted multi-scale digital image correlation analysis is used to track both elongations and rotations of particular features of the unit cell at the local and global (homogenized) scale of the material. This permits to observe with unprecedented clarity the strain fields for various unit cells in the structure and to detect global deformation patterns and heterogeneities of the homogenized strain distribution. This method is here demonstrated on elastic sheets undergoing extreme longitudinal and shear deformations. These experimental results are compared to non-linear finite element simulations, which are also used to evaluate the effects of manufacturing imperfections on the response. A skeletal representation of the architectured solid is then extracted from the experiments and used to create a purely-kinematic truss-hinge model that can accurately capture its behaviour. The analysis proposed in this work can be extended to guide the design of two-dimensional architectured solids featuring other regular, quasi-regular or graded patterns, and subjected to other types of loads.", "doi": "10.1016/j.ijmecsci.2020.106205", "issn": "0020-7403", "publisher": "Elsevier", "publication": "International Journal of Mechanical Sciences", "publication_date": "2021-03-15", "volume": "194", "pages": "Art. No. 106205" }, { "id": "authors:nq24v-j3e61", "collection": "authors", "collection_id": "nq24v-j3e61", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210302-145906582", "type": "article", "title": "Experimental realization of phonon demultiplexing in three-dimensions", "author": [ { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-Osama-R" }, { "family_name": "Yee", "given_name": "Chern Hwee", "clpid": "Yee-Chern-Hwee" }, { "family_name": "Rys", "given_name": "Jan", "clpid": "Rys-Jan" }, { "family_name": "Schumacher", "given_name": "Christian", "orcid": "0000-0001-7975-1680", "clpid": "Schumacher-Christian" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Phononic metamaterials enabled the realization of many acoustic components analogous to their electronic counterparts, such as transistors, logic gates, and calculators. A key component among these is the demultiplexer, a device that receives multiple signals and sorts them based on their frequencies into separate channels. Previous experimental realizations of acoustic and elastic multiplexers have employed plates with pillars or holes to demultiplex frequencies. However, existing realizations are confined to two dimensions, which can limit potential acoustic or elastic circuit design. Here, we show an experimental realization of a three-dimensional, four channel phononic demultiplexer. Our design methodology is based on bundles of pass-bands within a large bandgap that can easily be tuned for multi-channel frequency demultiplexing. The proposed design can be utilized in acoustic and elastic information processing, nondestructive evaluation, and communication applications, among others.", "doi": "10.1063/5.0030830", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2021-03-01", "series_number": "9", "volume": "118", "issue": "9", "pages": "Art. No. 091901" }, { "id": "authors:gvpsy-q0m28", "collection": "authors", "collection_id": "gvpsy-q0m28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210318-090144893", "type": "article", "title": "Parametric oscillation of electromagnetic waves in momentum band gaps of a spatiotemporal crystal", "author": [ { "family_name": "Lee", "given_name": "Seojoo", "clpid": "Lee-Seojoo" }, { "family_name": "Park", "given_name": "Jagang", "clpid": "Park-Jagang" }, { "family_name": "Cho", "given_name": "Hyukjoon", "clpid": "Cho-Hyukjoon" }, { "family_name": "Wang", "given_name": "Yifan", "orcid": "0000-0001-9965-9777", "clpid": "Wang-Yifan" }, { "family_name": "Kim", "given_name": "Brian", "clpid": "Kim-Brian" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Min", "given_name": "Bumki", "orcid": "0000-0002-4639-3423", "clpid": "Min-Bumki" } ], "abstract": "Photonic crystals have revolutionized the field of optics with their unique dispersion and energy band gap engineering capabilities, such as the demonstration of extreme group and phase velocities, topologically protected photonic edge states, and control of spontaneous emission of photons. Time-variant media have also shown distinct functionalities, including nonreciprocal propagation, frequency conversion, and amplification of light. However, spatiotemporal modulation has mostly been studied as a simple harmonic wave function. Here, we analyze time-variant and spatially discrete photonic crystal structures, referred to as spatiotemporal crystals. The design of spatiotemporal crystals allows engineering of the momentum band gap within which parametric amplification can occur. As a potential platform for the construction of a parametric oscillator, a finite-sized spatiotemporal crystal is proposed and analyzed. Parametric oscillation is initiated by the energy and momentum conversion of an incident wave and the subsequent amplification by parametric gain within the momentum band gap. The oscillation process dominates over frequency mixing interactions above a transition threshold determined by the balance between gain and loss. Furthermore, the asymmetric formation of momentum band gaps can be realized by spatial phase control of the temporal modulation, which leads to directional radiation of oscillations at distinct frequencies. The proposed structure would enable simultaneous engineering of energy and momentum band gaps and provide a guideline for implementation of advanced dispersion-engineered parametric oscillators.", "doi": "10.1364/prj.406215", "issn": "2327-9125", "publisher": "Optical Society of America", "publication": "Photonics Research", "publication_date": "2021-02-01", "series_number": "2", "volume": "9", "issue": "2", "pages": "142-150" }, { "id": "authors:bkk81-rnz76", "collection": "authors", "collection_id": "bkk81-rnz76", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210112-081547169", "type": "article", "title": "Photosynthesis-assisted remodeling of three-dimensional printed structures", "author": [ { "family_name": "Yu", "given_name": "Kunhao", "orcid": "0000-0003-2306-1175", "clpid": "Yu-Kunhao" }, { "family_name": "Feng", "given_name": "Zhangzhengrong", "orcid": "0000-0001-8271-2543", "clpid": "Feng-Zhangzhengrong" }, { "family_name": "Du", "given_name": "Haixu", "clpid": "Du-Haixu" }, { "family_name": "Xin", "given_name": "An", "clpid": "Xin-An" }, { "family_name": "Lee", "given_name": "Kyung Hoon", "orcid": "0000-0002-8187-3262", "clpid": "Lee-Kyung-Hoon" }, { "family_name": "Li", "given_name": "Ketian", "clpid": "Li-Ketian" }, { "family_name": "Su", "given_name": "Yipin", "clpid": "Su-Yipin" }, { "family_name": "Wang", "given_name": "Qiming", "clpid": "Wang-Qiming" }, { "family_name": "Fang", "given_name": "Nicholas X.", "orcid": "0000-0001-5713-629X", "clpid": "Fang-Nicholas-X" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The mechanical properties of engineering structures continuously weaken during service life because of material fatigue or degradation. By contrast, living organisms are able to strengthen their mechanical properties by regenerating parts of their structures. For example, plants strengthen their cell structures by transforming photosynthesis-produced glucose into stiff polysaccharides. In this work, we realize hybrid materials that use photosynthesis of embedded chloroplasts to remodel their microstructures. These materials can be used to three-dimensionally (3D)-print functional structures, which are endowed with matrix-strengthening and crack healing when exposed to white light. The mechanism relies on a 3D-printable polymer that allows for an additional cross-linking reaction with photosynthesis-produced glucose in the material bulk or on the interface. The remodeling behavior can be suspended by freezing chloroplasts, regulated by mechanical preloads, and reversed by environmental cues. This work opens the door for the design of hybrid synthetic-living materials, for applications such as smart composites, lightweight structures, and soft robotics.", "doi": "10.1073/pnas.2016524118", "pmcid": "PMC7826334", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2021-01-19", "series_number": "3", "volume": "118", "issue": "3", "pages": "Art. No. e2016524118" }, { "id": "authors:7r1eh-6pk43", "collection": "authors", "collection_id": "7r1eh-6pk43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201214-121033243", "type": "article", "title": "Structure and Biomechanics during Xylem Vessel Transdifferentiation in Arabidopsis thaliana", "author": [ { "family_name": "Roumeli", "given_name": "Eleftheria", "orcid": "0000-0002-2828-1428", "clpid": "Roumeli-Eleftheria" }, { "family_name": "Ginsberg", "given_name": "Leah", "orcid": "0000-0001-9685-7014", "clpid": "Ginsberg-Leah" }, { "family_name": "McDonald", "given_name": "Robin", "clpid": "McDonald-Robin" }, { "family_name": "Spigolon", "given_name": "Giada", "orcid": "0000-0002-1704-8372", "clpid": "Spigolon-Giada" }, { "family_name": "Hendrickx", "given_name": "Rodinde", "clpid": "Hendrickx-Rodinde" }, { "family_name": "Ohtani", "given_name": "Misato", "orcid": "0000-0001-5429-3310", "clpid": "Ohtani-Misato" }, { "family_name": "Demura", "given_name": "Taku", "orcid": "0000-0002-2499-4738", "clpid": "Demura-Taku" }, { "family_name": "Ravichandran", "given_name": "Guruswami", "orcid": "0000-0002-2912-0001", "clpid": "Ravichandran-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Individual plant cells are the building blocks for all plantae and artificially constructed plant biomaterials, like biocomposites. Secondary cell walls (SCWs) are a key component for mediating mechanical strength and stiffness in both living vascular plants and biocomposite materials. In this paper, we study the structure and biomechanics of cultured plant cells during the cellular developmental stages associated with SCW formation. We use a model culture system that induces transdifferentiation of Arabidopsis thaliana cells to xylem vessel elements, upon treatment with dexamethasone (DEX). We group the transdifferentiation process into three distinct stages, based on morphological observations of the cell walls. The first stage includes cells with only a primary cell wall (PCW), the second covers cells that have formed a SCW, and the third stage includes cells with a ruptured tonoplast and partially or fully degraded PCW. We adopt a multi-scale approach to study the mechanical properties of cells in these three stages. We perform large-scale indentations with a micro-compression system in three different osmotic conditions. Atomic force microscopy (AFM) nanoscale indentations in water allow us to isolate the cell wall response. We propose a spring-based model to deconvolve the competing stiffness contributions from turgor pressure, PCW, SCW and cytoplasm in the stiffness of differentiating cells. Prior to triggering differentiation, cells in hypotonic pressure conditions are significantly stiffer than cells in isotonic or hypertonic conditions, highlighting the dominant role of turgor pressure. Plasmolyzed cells with a SCW reach similar levels of stiffness as cells with maximum turgor pressure. The stiffness of the PCW in all of these conditions is lower than the stiffness of the fully-formed SCW. Our results provide the first experimental characterization of the mechanics of SCW formation at single cell level.", "doi": "10.3390/plants9121715", "pmcid": "PMC7762020", "issn": "2223-7747", "publisher": "MDPI AG", "publication": "Plants", "publication_date": "2020-12-05", "series_number": "12", "volume": "9", "issue": "12", "pages": "Art. No. 1715" }, { "id": "authors:hbztc-ws372", "collection": "authors", "collection_id": "hbztc-ws372", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201012-142057607", "type": "article", "title": "Surface wave non-reciprocity via time-modulated metamaterials", "author": [ { "family_name": "Palermo", "given_name": "A.", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-A" }, { "family_name": "Celli", "given_name": "P.", "orcid": "0000-0001-7839-7472", "clpid": "Celli-P" }, { "family_name": "Yousefzadeh", "given_name": "B.", "clpid": "Yousefzadeh-B" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Marzani", "given_name": "A.", "clpid": "Marzani-A" } ], "abstract": "We investigate how Rayleigh waves interact with time-modulated resonators located on the free surface of a semi-infinite elastic medium. We begin by studying the dynamics of a single resonator with time-modulated stiffness, we evaluate the accuracy of an analytical approximation of the resonator response and identify the parameter ranges in which its behavior remains stable. Then, we develop an analytical model to describe the interaction between surface waves and an array of resonators with spatio-temporally modulated stiffness. By combining our analytical models with full-scale numerical simulations, we demonstrate that spatio-temporal stiffness modulation of this elastic metasurface leads to the emergence of non-reciprocal features in the Rayleigh wave spectrum. Specifically, we show how the frequency content of a propagating signal can be filtered and converted when traveling through the modulated medium, and illustrate how surface-to-bulk wave conversion plays a role in these phenomena. Throughout this article, we indicate bounds of modulation parameters for which our theory is reliable, thus providing guidelines for future experimental studies on the topic.", "doi": "10.1016/j.jmps.2020.104181", "issn": "0022-5096", "publisher": "Elsevier", "publication": "Journal of the Mechanics and Physics of Solids", "publication_date": "2020-12", "volume": "145", "pages": "Art. No. 104181" }, { "id": "authors:g6mk7-bjg25", "collection": "authors", "collection_id": "g6mk7-bjg25", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200615-091613952", "type": "article", "title": "Compliant morphing structures from twisted bulk metallic glass ribbons", "author": [ { "family_name": "Celli", "given_name": "P.", "orcid": "0000-0001-7839-7472", "clpid": "Celli-P" }, { "family_name": "Lamaro", "given_name": "A.", "clpid": "Lamaro-A" }, { "family_name": "McMahan", "given_name": "C.", "orcid": "0000-0001-5024-6138", "clpid": "McMahan-C" }, { "family_name": "Bordeenithikasem", "given_name": "P.", "orcid": "0000-0002-0590-2447", "clpid": "Bordeenithikasem-P" }, { "family_name": "Hofmann", "given_name": "D. C.", "clpid": "Hofmann-D-C" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In this work, we investigate the use of pre-twisted metallic ribbons as building blocks for shape-changing structures. We manufacture these elements by twisting initially flat ribbons about their (lengthwise) centroidal axis into a helicoidal geometry, then thermoforming them to make this configuration a stress-free reference state. The helicoidal shape allows the ribbons to have preferred bending directions that vary throughout their length. These bending directions serve as compliant joints and enable several deployed and stowed configurations that are unachievable without pre-twist, provided that compaction does not induce material failure. We fabricate these ribbons using a bulk metallic glass (BMG), for its exceptional elasticity and thermoforming attributes. Combining numerical simulations, an analytical model based on a geometrically nonlinear plate theory and torsional experiments, we analyze the finite-twisting mechanics of various ribbon geometries. We find that, in ribbons with undulated edges, the twisting deformations can be better localized onto desired regions prior to thermoforming. Finally, we join multiple ribbons to create deployable systems with complex morphing attributes enabled by the intrinsic chirality of our twisted structural elements. Our work proposes a framework for creating fully metallic, yet compliant structures that may find application as elements for space structures and compliant robots.", "doi": "10.1016/j.jmps.2020.104129", "issn": "0022-5096", "publisher": "Elsevier", "publication": "Journal of the Mechanics and Physics of Solids", "publication_date": "2020-12", "volume": "145", "pages": "Art. No. 104129" }, { "id": "authors:c7ez3-3db50", "collection": "authors", "collection_id": "c7ez3-3db50", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200723-122440892", "type": "article", "title": "Nonreciprocity in acoustic and elastic materials", "author": [ { "family_name": "Nassar", "given_name": "Hussein", "orcid": "0000-0001-7235-4498", "clpid": "Nassar-Hussein" }, { "family_name": "Yousefzadeh", "given_name": "Behrooz", "orcid": "0000-0002-6973-717X", "clpid": "Yousefzadeh-B" }, { "family_name": "Fleury", "given_name": "Romain", "orcid": "0000-0002-9486-6854", "clpid": "Fleury-R" }, { "family_name": "Ruzzene", "given_name": "Massimo", "orcid": "0000-0002-1502-2160", "clpid": "Ruzzene-M" }, { "family_name": "Al\u00f9", "given_name": "Andrea", "orcid": "0000-0002-4297-5274", "clpid": "Al\u00f9-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Norris", "given_name": "Andrew N.", "orcid": "0000-0001-7577-3698", "clpid": "Norris-A-N" }, { "family_name": "Huang", "given_name": "Guoliang", "orcid": "0000-0002-6238-6127", "clpid": "Huang-Guoliang" }, { "family_name": "Haberman", "given_name": "Michael R.", "orcid": "0000-0002-7159-9773", "clpid": "Haberman-M-R" } ], "abstract": "The law of reciprocity in acoustics and elastodynamics codifies a relation of symmetry between action and reaction in fluids and solids. In its simplest form, it states that the frequency-response functions between any two material points remain the same after swapping source and receiver, regardless of the presence of inhomogeneities and losses. As such, reciprocity has enabled numerous applications that make use of acoustic and elastic wave propagation. A recent change in paradigm has prompted us to see reciprocity under a new light: as an obstruction to the realization of wave-bearing media in which the source and receiver are not interchangeable. Such materials may enable the creation of devices such as acoustic one-way mirrors, isolators and topological insulators. Here, we review how reciprocity breaks down in materials with momentum bias, structured space-dependent and time-dependent constitutive properties, and constitutive nonlinearity, and report on recent advances in the modelling and fabrication of these materials, as well as on experiments demonstrating nonreciprocal acoustic and elastic wave propagation therein. The success of these efforts holds promise to enable robust, unidirectional acoustic and elastic wave-steering capabilities that exceed what is currently possible in conventional materials, metamaterials or phononic crystals.", "doi": "10.1038/s41578-020-0206-0", "issn": "2058-8437", "publisher": "Nature Publishing Group", "publication": "Nature Reviews Materials", "publication_date": "2020-09", "series_number": "9", "volume": "5", "issue": "9", "pages": "667-685" }, { "id": "authors:hbygc-kfq82", "collection": "authors", "collection_id": "hbygc-kfq82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200624-104212835", "type": "article", "title": "A Flexible Spiraling\u2010Metasurface as a Versatile Haptic Interface", "author": [ { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-O-R" }, { "family_name": "Costanza", "given_name": "Vincenzo", "orcid": "0000-0002-2409-0632", "clpid": "Costanza-V" }, { "family_name": "Israr", "given_name": "Ali", "clpid": "Israr-Ali" }, { "family_name": "Palermo", "given_name": "Antonio", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-A" }, { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-P" }, { "family_name": "Lau", "given_name": "Frances", "clpid": "Lau-Frances" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Haptic feedback is the most significant sensory interface following visual cues. Developing thin, flexible surfaces that function as haptic interfaces is important for augmenting virtual reality, wearable devices, robotics and prostheses. For example, adding a haptic feedback interface to prosthesis could improve their acceptance among amputees. State of the art programmable interfaces targeting the skin feel\u2010of\u2010touch through mechano\u2010receptors are limited by inadequate sensory feedback, cumbersome mechanisms, or narrow frequency of operation. Here, a flexible metasurface is presented as a generic haptic interface capable of producing complex tactile patterns on the human skin at wide range of frequencies. The metasurface is composed of multiple \"pixels\" that can locally amplify both input displacements and forces. Each of these pixels encodes various deformation patterns capable of producing different sensations on contact. The metasurface can transform a harmonic signal containing multiple frequencies into a complex preprogrammed tactile pattern. The findings, corroborated by user studies conducted on human candidates, can open new avenues for wearable and robotic interfaces.", "doi": "10.1002/admt.202000181", "issn": "2365-709X", "publisher": "Wiley", "publication": "Advanced Materials Technologies", "publication_date": "2020-08", "series_number": "8", "volume": "5", "issue": "8", "pages": "Art. No. 2000181" }, { "id": "authors:pfbt6-xmd73", "collection": "authors", "collection_id": "pfbt6-xmd73", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200813-094025637", "type": "article", "title": "Enhancement of Deep-Subwavelength Band Gaps in Flat Spiral-Based Phononic Metamaterials Using the Trampoline Phenomena", "author": [ { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-O-R" }, { "family_name": "Foehr", "given_name": "Andr\u00e9", "orcid": "0000-0003-0941-5424", "clpid": "Foehr-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Elastic and acoustic metamaterials can sculpt dispersion of waves through resonances. In turn, resonances can give rise to negative effective properties, usually localized around the resonance frequencies, which support band gaps at subwavelength frequencies (i.e., below the Bragg-scattering limit). However, the band gaps width correlates strongly with the resonators' mass and volume, which limits their functionality in applications. Trampoline phenomena have been numerically and experimentally shown to broaden the operational frequency ranges of two-dimensional, pillar-based metamaterials through perforation. In this work, we demonstrate trampoline phenomena in lightweight and planar lattices consisting of arrays of Archimedean spirals in unit cells. Spiral-based metamaterials have been shown to support different band gap opening mechanisms, namely, Bragg-scattering, local resonances and inertia amplification. Here, we numerically analyze and experimentally realize trampoline phenomena in planar metasurfaces for different lattice tessellations. Finally, we carry out a comparative study between trampoline pillars and spirals and show that trampoline spirals outperform the pillars in lightweight, compactness and operational bandwidth.", "doi": "10.1115/1.4046893", "issn": "0021-8936", "publisher": "American Society of Mechanical Engineers", "publication": "Journal of Applied Mechanics", "publication_date": "2020-07", "series_number": "7", "volume": "87", "issue": "7", "pages": "Art. No. 071009" }, { "id": "authors:a5xak-dek65", "collection": "authors", "collection_id": "a5xak-dek65", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191024-101104702", "type": "article", "title": "Temperature-induced shape morphing of bi-metallic structures", "author": [ { "family_name": "Taniker", "given_name": "S.", "clpid": "Taniker-S" }, { "family_name": "Cellia", "given_name": "P.", "clpid": "Cellia-P" }, { "family_name": "Pasini", "given_name": "D.", "clpid": "Pasini-D" }, { "family_name": "Hofmann", "given_name": "D. C.", "clpid": "Hofmann-D-C" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In this work, we study the thermo-mechanical behavior of metallic structures designed to significantly change shape in response to thermal stimuli. This behavior is achieved by arranging two metals with different coefficient of thermal expansion (CTE), Aluminum and Titanium, as to create displacement-amplifying units that can expand uniaxially. In particular, our design comprises a low-CTE bar surrounded by a high-CTE frame that features flexure hinges and thicker links. When the temperature increases, the longitudinal expansion of the high-CTE portion is geometrically constrained by the low-CTE bar, resulting in a large tangential displacement. Our design is guided by theoretical models and numerical simulations. We validate our approach by fabricating and characterizing individual units, one dimensional arrays and three-dimensional structures. Our work shows that structurally robust metallic structures can be designed for large shape changes. The results also demonstrate how harsh environmental conditions (e.g., the extreme temperature swings that are characteristic of extraterrestrial environments) can be leveraged to produce function in a fully passive way.", "doi": "10.1016/j.ijsolstr.2019.10.024", "issn": "0020-7683", "publisher": "Elsevier", "publication": "International Journal of Solids and Structures", "publication_date": "2020-05-01", "volume": "190", "pages": "22-32" }, { "id": "authors:fffr8-1yj79", "collection": "authors", "collection_id": "fffr8-1yj79", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200323-104524705", "type": "article", "title": "Neural networks for trajectory evaluation in direct laser writing", "author": [ { "family_name": "Bauhofer", "given_name": "Anton", "clpid": "Bauhofer-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Material shrinkage commonly occurs in additive manufacturing and compromises the fabrication quality by causing unwanted distortions or residual stresses in fabricated parts. Even though it is known that the resulting deformations and stresses are highly dependent on the writing trajectory, no effective strategy for choosing suitable trajectories has been reported to date. Here, we present a path to achieve this goal in direct laser writing, an additive manufacturing method based on photopolymerization that commonly suffers from strong shrinkage-induced effects. First, we introduce a method for measuring the shrinkage of distinct direct laser written lines. We then introduce a semi-empirical numerical model to capture the interplay of sequentially polymerized material and the resulting macroscopic effects. Finally, we implement an artificial neural network to evaluate given laser trajectories in terms of the resulting part quality. The presented approach proves feasibility of using artificial neural networks to assess the quality of 3D printing trajectories and thereby demonstrates a potential route for reducing the impact of material shrinkage on 3D printed parts.", "doi": "10.1007/s00170-020-05086-3", "issn": "0268-3768", "publisher": "Springer", "publication": "International Journal of Advanced Manufacturing Technology", "publication_date": "2020-03", "series_number": "5-6", "volume": "107", "issue": "5-6", "pages": "2563-2577" }, { "id": "authors:9w0n5-zah18", "collection": "authors", "collection_id": "9w0n5-zah18", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200311-155918643", "type": "monograph", "title": "Enhancement of deep-subwavelength band gaps in flat spiral-based phononic metasurfaces using the trampoline phenomena", "author": [ { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-O-R" }, { "family_name": "Foehr", "given_name": "Andr\u00e9", "orcid": "0000-0003-0941-5424", "clpid": "Foehr-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Elastic and acoustic metamaterials can sculpt dispersion of waves through resonances. In turn, resonances can give rise to negative effective properties, usually localized around the resonance frequencies, which support band gaps at subwavelength frequencies (i.e., below the Bragg-scattering limit). However, the band gaps width correlates strongly with the resonators' mass and volume, which limits their functionality in applications. Trampoline phenomena have been numerically and experimentally shown to broaden the operational frequency ranges of two-dimensional, pillar-based metamaterials through perforation. In this work, we demonstrate trampoline phenomena in lightweight and planar lattices consisting of arrays of Archimedean spirals in unit cells. Spiral-based metamaterials have been shown to support different band gap opening mechanisms, namely, Bragg-scattering, local resonances and inertia amplification. Here, we numerically analyze and experimentally realize trampoline phenomena in planar metasurfaces for different lattice tessellations. Finally, we carry out a comparative study between trampoline pillars and spirals and show that trampoline spirals outperform the pillars in lightweight, compactness and operational bandwidth.", "doi": "10.48550/arXiv.2001.10508", "publisher": "arXiv", "publication_date": "2020-01-28" }, { "id": "authors:cq2rr-evb20", "collection": "authors", "collection_id": "cq2rr-evb20", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200113-130413229", "type": "article", "title": "Programming temporal morphing of self-actuated shells", "author": [ { "family_name": "Guseinov", "given_name": "Ruslan", "orcid": "0000-0001-9819-5077", "clpid": "Guseinov-Ruslan" }, { "family_name": "McMahan", "given_name": "Connor", "orcid": "0000-0001-5024-6138", "clpid": "McMahan-Connor" }, { "family_name": "P\u00e9rez", "given_name": "Jes\u00fas", "orcid": "0000-0001-5085-6681", "clpid": "P\u00e9rez-Jes\u00fas" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Bickel", "given_name": "Bernd", "orcid": "0000-0001-6511-9385", "clpid": "Bickel-Bernd" } ], "abstract": "Advances in shape-morphing materials, such as hydrogels, shape-memory polymers and light-responsive polymers have enabled prescribing self-directed deformations of initially flat geometries. However, most proposed solutions evolve towards a target geometry without considering time-dependent actuation paths. To achieve more complex geometries and avoid self-collisions, it is critical to encode a spatial and temporal shape evolution within the initially flat shell. Recent realizations of time-dependent morphing are limited to the actuation of few, discrete hinges and cannot form doubly curved surfaces. Here, we demonstrate a method for encoding temporal shape evolution in architected shells that assume complex shapes and doubly curved geometries. The shells are non-periodic tessellations of pre-stressed contractile unit cells that soften in water at rates prescribed locally by mesostructure geometry. The ensuing midplane contraction is coupled to the formation of encoded curvatures. We propose an inverse design tool based on a data-driven model for unit cells' temporal responses.", "doi": "10.1038/s41467-019-14015-2", "pmcid": "PMC6957700", "issn": "2041-1723", "publisher": "Nature Publishing Group", "publication": "Nature Communications", "publication_date": "2020-01-13", "volume": "11", "pages": "Art. No. 237" }, { "id": "authors:03xm9-d8719", "collection": "authors", "collection_id": "03xm9-d8719", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190802-154910921", "type": "article", "title": "Acoustic Non-Reciprocity in Lattices With Nonlinearity, Internal Hierarchy, and Asymmetry: Computational Study", "author": [ { "family_name": "Fronk", "given_name": "Matthew D.", "clpid": "Fronk-M-D" }, { "family_name": "Tawfick", "given_name": "Sameh", "clpid": "Tawfick-S" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Li", "given_name": "Shuangbao", "clpid": "Li-Shuangbao" }, { "family_name": "Vakakis", "given_name": "Alexander", "clpid": "Vakakis-A-F" }, { "family_name": "Leamy", "given_name": "Michael J.", "clpid": "Leamy-M-J" } ], "abstract": "Reciprocity is a property of linear, time-invariant systems whereby the energy transmission from a source to a receiver is unchanged after exchanging the source and receiver. Nonreciprocity violates this property and can be introduced to systems if time-reversal symmetry and/or parity symmetry is lost. While many studies have induced nonreciprocity by active means, i.e., odd-symmetric external biases or time variation of system properties, considerably less attention has been given to acoustical structures that passively break reciprocity. This study presents a lattice structure with strong stiffness nonlinearities, internal scale hierarchy, and asymmetry that breaks acoustic reciprocity. Macroscopically, the structure exhibits periodicity yet asymmetry exists in its unit cell design. A theoretical study, supported by experimental validation, of a two-scale unit cell has revealed that reciprocity is broken locally, i.e., within a single unit cell of the lattice. In this work, global breaking of reciprocity in the entire lattice structure is theoretically analyzed by studying wave propagation in the periodic arrangement of unit cells. Under both narrowband and broadband excitation, the structure exhibits highly asymmetrical wave propagation, and hence a global breaking of acoustic reciprocity. Interpreting the numerical results for varying impulse amplitude, as well as varying harmonic forcing amplitude and frequency/wavenumber, provides strong evidence that transient resonant capture is the driving force behind the global breaking of reciprocity in the periodic structure. In a companion work, some of the theoretical results presented herein are experimentally validated with a lattice composed of two-scale unit cells under impulsive excitation.", "doi": "10.1115/1.4043783", "issn": "1048-9002", "publisher": "American Society of Mechanical Engineers", "publication": "Journal of Vibration and Acoustics", "publication_date": "2019-12", "series_number": "5", "volume": "141", "issue": "5", "pages": "Art. No. 051011" }, { "id": "authors:9gz8j-0n622", "collection": "authors", "collection_id": "9gz8j-0n622", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191111-154114590", "type": "article", "title": "Metamaterials with engineered failure load and stiffness", "author": [ { "family_name": "Injeti", "given_name": "Sai Sharan", "clpid": "Injeti-S-S" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Bhattacharya", "given_name": "Kaushik", "orcid": "0000-0003-2908-5469", "clpid": "Bhattacharya-K" } ], "abstract": "Architected materials or metamaterials have proved to be a very effective way of making materials with unusual mechanical properties. For example, by designing the mesoscale geometry of architected materials, it is possible to obtain extremely high stiffness-to-weight ratio or unusual Poisson's ratio. However, much of this work has focused on designing properties like stiffness and density, and much remains unknown about the critical load to failure. This is the focus of the current work. We show that the addition of local internal prestress in selected regions of architected materials enables the design of materials where the critical load to failure can be optimized independently from the density and/or quasistatic stiffness. We propose a method to optimize the specific load to failure and specific stiffness using sensitivity analysis and derive the maximum bounds on the attainable properties. We demonstrate the method in a 2D triangular lattice and a 3D octahedral truss, showing excellent agreement between experimental and theoretical results. The method can be used to design materials with predetermined fracture load, failure location, and fracture paths.", "doi": "10.1073/pnas.1911535116", "pmcid": "PMC6883817", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2019-11-26", "series_number": "48", "volume": "116", "issue": "48", "pages": "23960-23965" }, { "id": "authors:scb9y-ppa15", "collection": "authors", "collection_id": "scb9y-ppa15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190709-111117888", "type": "article", "title": "Design and Impact Response of 3D-Printable Tensegrity-Inspired Structures", "author": [ { "family_name": "Pajunen", "given_name": "Kirsti", "clpid": "Pajunen-K" }, { "family_name": "Johanns", "given_name": "Paul", "orcid": "0000-0002-3093-6753", "clpid": "Johanns-P" }, { "family_name": "Pal", "given_name": "Raj Kumar", "orcid": "0000-0001-5039-7710", "clpid": "Pal-R-K" }, { "family_name": "Rimoli", "given_name": "Julian J.", "orcid": "0000-0002-8707-2968", "clpid": "Rimoli-J-J" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Recent studies demonstrate the potential of tensegrity structures as unique building blocks for architected lattices (metamaterials). Key tensegrity characteristics, such as elastic response under severe deformation, high strength-to-weight ratio, and nonlinear behavior, make these structures appealing for dynamic applications. A new method of tessellating tensegrity unit cells with elastically buckling struts in three dimensions has opened new avenues for metamaterials with superior mechanical properties. However, traditional fabrication methods for tensegrity structures are cumbersome and do not allow accurate control of the level of member prestress. To overcome these limitations, we present a design of a 3D-printable, single material structure which has comparable strain energy capacity and compressive response as a tensegrity structure with buckling struts. The structure's geometry maintains key tensegrity characteristics, thus generating an equivalent mechanical response. Numerical simulations inform quasistatic compression experiments and dynamic drop weight impact tests. The structure's responses correspond well to the pin-jointed tensegrity, exhibiting desirable characteristics such as post-buckling stability, resilience under severe deformation, high elastic strain energy absorption, and load-limitation. This work is the first to experimentally corroborate theoretical studies of buckling tensegrity structures. We conjecture that the structure presented here has unique potential as a unit cell for manufacturable tensegrity-inspired metamaterials.", "doi": "10.1016/j.matdes.2019.107966", "issn": "0264-1275", "publisher": "Elsevier", "publication": "Materials and Design", "publication_date": "2019-11-15", "volume": "182", "pages": "Art. No. 107966" }, { "id": "authors:3n0es-s7x33", "collection": "authors", "collection_id": "3n0es-s7x33", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191107-073748308", "type": "article", "title": "Effect of glycerol on the mechanical and temperature-sensing properties of pectin films", "author": [ { "family_name": "Costanza", "given_name": "Vincenzo", "orcid": "0000-0002-2409-0632", "clpid": "Costanza-Vincenzo" }, { "family_name": "Bonanomi", "given_name": "Luca", "clpid": "Bonanomi-Luca" }, { "family_name": "Moscato", "given_name": "Giovanni", "orcid": "0000-0001-5326-143X", "clpid": "Moscato-Giovanni" }, { "family_name": "Wang", "given_name": "Linghui", "clpid": "Wang-Linghui" }, { "family_name": "Choi", "given_name": "Yeong Suk", "orcid": "0000-0002-7231-9921", "clpid": "Choi-Yeong-Suk" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Temperature-sensitive films embedded in electronic skins (e-skins) can provide temperature feedback to robots, high-tech prostheses, and wearable devices for health care monitoring. Pectin-based films have shown a temperature response at least two orders of magnitude higher than previously reported temperature-sensing materials. However, they are not easily stretchable and tearable, which limit their applications as e-skins that require repetitive bending and mechanical stresses. Here, we show how the addition of glycerol as a plasticizer in the fabrication of pectin-based films improves their mechanical properties. We report how the enhancement of the mechanical performance is accompanied by a decrease in the temperature responsivity. Through thermogravimetric analysis, we show that this reduction in responsivity can be associated with water retention due to the addition of the plasticizer. The link between the water content and the temperature response demonstrates that a dehydrated status of pectin is crucial to record its high temperature responsivity. Combining electrical and thermal characterization with the tensile strength test, we estimate the optimal concentration of glycerol for improving the mechanical properties without compromising the temperature response of the pectin films.", "doi": "10.1063/1.5121710", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2019-11-04", "series_number": "19", "volume": "115", "issue": "19", "pages": "Art. No. 193702" }, { "id": "authors:nnqm6-8nn95", "collection": "authors", "collection_id": "nnqm6-8nn95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190919-124613335", "type": "article", "title": "Architected lattices with adaptive energy absorption", "author": [ { "family_name": "Wang", "given_name": "Yifan", "orcid": "0000-0001-9965-9777", "clpid": "Wang-Yifan" }, { "family_name": "Ramirez", "given_name": "Brian", "clpid": "Ramirez-B" }, { "family_name": "Carpenter", "given_name": "Kalind", "orcid": "0000-0002-1085-9949", "clpid": "Carpenter-K" }, { "family_name": "Naify", "given_name": "Christina", "clpid": "Naify-C" }, { "family_name": "Hofmann", "given_name": "Douglas C.", "clpid": "Hofmann-D-C" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Energy absorbing materials, like foams used in protective equipment, are able to undergo large deformations under low stresses, reducing the incoming stress wave below an injury or damage threshold. They are typically effective in absorbing energy through plastic deformation or fragmentation. However, existing solutions are passive, only effective against specific threats and they are usually damaged after use. Here, we overcome these limitations designing energy absorbing materials that use architected lattices filled with granular particles. We use architected lattices to take advantage of controlled bending and buckling of members to enhance energy absorption. We actively control the negative pressure level within the lattices, to tune the jamming phase transition of the granular particles, inducing controllable energy absorption and recoverable deformations. Our system shows tunable stiffness and yield strength by over an order of magnitude, and reduces the transmitted impact stress at different levels by up to 40% compared to the passive lattice. The demonstrated adaptive energy absorbing system sees wide potential applications from personal protective equipment, vehicle safety systems to aerospace structures.", "doi": "10.1016/j.eml.2019.100557", "issn": "2352-4316", "publisher": "Elsevier", "publication": "Extreme Mechanics Letters", "publication_date": "2019-11", "volume": "33", "pages": "Art. No. 100557" }, { "id": "authors:0twct-x4p37", "collection": "authors", "collection_id": "0twct-x4p37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-105133177", "type": "article", "title": "Energy Absorption Properties of Periodic and Stochastic 3D Lattice Materials", "author": [ { "family_name": "Mueller", "given_name": "Jochen", "orcid": "0000-0002-4808-2223", "clpid": "Mueller-Jochen" }, { "family_name": "Matlack", "given_name": "Kathryn H.", "orcid": "0000-0001-7387-2414", "clpid": "Matlack-K-H" }, { "family_name": "Shea", "given_name": "Kristina", "orcid": "0000-0003-3921-2214", "clpid": "Shea-Kristina" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Architected lattices can be designed to have tailorable functionalities by controlling their constitutive elements. However, little work has been devoted to comparing energy absorption properties in different periodic three\u2010dimensional geometries to each other and to comparable foam\u2010like random structures. This knowledge is essential for the entire design process. In this work, the authors conduct a systematic and comprehensive computational study of the quasi\u2010static and dynamic energy absorption properties of various different geometries. They test compression loading over strain rates varying from 1 to 10^4 s^(\u22121). The authors analyze geometries with varying degrees of nodal connectivity, ranging from bending dominated to stretching dominated, at different orientations, and compare their response to equivalent stochastic lattices. Results show relatively high stress peaks in the periodic lattices, even in bending dominated lattices at certain orientations. Conversely, the stochastic geometries show a relatively constant stress response over large strains, which is ideal for energy absorbing applications. Still, results show that specific orientations of bending dominated periodic lattice geometries outperform their stochastic equivalents. This work can help to quickly identify the potential of different unit cell types and aid in the development of lattices for impulse mitigation applications, such as in protective sports equipment, automotive crashworthiness, and packaging.", "doi": "10.1002/adts.201900081", "issn": "2513-0390", "publisher": "Wiley", "publication": "Advanced Theory and Simulations", "publication_date": "2019-10", "series_number": "10", "volume": "2", "issue": "10", "pages": "Art. No. 1900081" }, { "id": "authors:eetpt-80303", "collection": "authors", "collection_id": "eetpt-80303", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191121-133313705", "type": "book_section", "title": "Controlling surface acoustic waves via magnetically-modulated contact resonances", "book_title": "2019 Thirteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials)", "author": [ { "family_name": "Palermo", "given_name": "A.", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-A" }, { "family_name": "Wang", "given_name": "Y.", "clpid": "Wang-Y" }, { "family_name": "Cellia", "given_name": "P.", "clpid": "Cellia-P" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We present a tabletop-scale realization of a tunable metamaterial platform to control surface acoustic waves (SAWs). The platform comprises an array of ferromagnetic beads controlled with permanent magnets, arranged atop an elastic substrate. We demonstrate the possibility of shifting the beads resonances and, in turn, tuning the SAWs bandgaps.", "doi": "10.1109/MetaMaterials.2019.8900928", "isbn": "978-1-7281-0477-5", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2019-09", "pages": "287-289" }, { "id": "authors:p84ar-6aw29", "collection": "authors", "collection_id": "p84ar-6aw29", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190802-142724805", "type": "article", "title": "Untethered soft robotic matter with passive control of shape morphing and propulsion", "author": [ { "family_name": "Kotikian", "given_name": "Arda", "clpid": "Kotikian-A" }, { "family_name": "McMahan", "given_name": "Connor", "orcid": "0000-0001-5024-6138", "clpid": "McMahan-C" }, { "family_name": "Davidson", "given_name": "Emily C.", "clpid": "Davidson-E-C" }, { "family_name": "Muhammad", "given_name": "Jalilah M.", "clpid": "Muhammad-Jalilah-M" }, { "family_name": "Weeks", "given_name": "Robert D.", "clpid": "Weeks-R-D" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Lewis", "given_name": "Jennifer A.", "clpid": "Lewis-J-A" } ], "abstract": "There is growing interest in creating untethered soft robotic matter that can repeatedly shape-morph and self-propel in response to external stimuli. Toward this goal, we printed soft robotic matter composed of liquid crystal elastomer (LCE) bilayers with orthogonal director alignment and different nematic-to-isotropic transition temperatures (T_(NI)) to form active hinges that interconnect polymeric tiles. When heated above their respective actuation temperatures, the printed LCE hinges exhibit a large, reversible bending response. Their actuation response is programmed by varying their chemistry and printed architecture. Through an integrated design and additive manufacturing approach, we created passively controlled, untethered soft robotic matter that adopts task-specific configurations on demand, including a self-twisting origami polyhedron that exhibits three stable configurations and a \"rollbot\" that assembles into a pentagonal prism and self-rolls in programmed responses to thermal stimuli.", "doi": "10.1126/scirobotics.aax7044", "issn": "2470-9476", "publisher": "American Association for the Advancement of Science", "publication": "Science Robotics", "publication_date": "2019-08-21", "series_number": "33", "volume": "4", "issue": "33", "pages": "Art. No. eaax7044" }, { "id": "authors:1w4j1-6qa14", "collection": "authors", "collection_id": "1w4j1-6qa14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190905-100614404", "type": "article", "title": "Editorial: Multiscale Lattices and Composite Materials: Optimal Design, Modeling and Characterization", "author": [ { "family_name": "Fraternali", "given_name": "Fernando", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Rimoli", "given_name": "Julian", "orcid": "0000-0002-8707-2968", "clpid": "Rimoli-J-J" } ], "abstract": "The Research Topic \"Multiscale lattices and composite materials:\" (MLCM) is focused on the optimal design, modeling, and characterization of novel lattices, composite materials, and structures at different scales, through the control of the internal architecture of the system. \n\nA fundamental goal of this article collection is the study of mechanical metamaterials that are able to form next-generation-generation cellular solids; lattice materials, multiscale composites; and structural-scale systems. The collection took inspiration from the peculiar behaviors exhibited by structured materials at multiple scales (Bosia et al., 2018). The latter include, for example, high stiffness, strength, and toughness at extremely low densities (Meza et al., 2014), phononic band-gaps (Lu et al., 2009), sound control ability (Cummer et al., 2016); negative effective mass density (Liu et al., 2000); localized confined waves (Theocharis et al., 2013), to name but a few examples. The research reported devoted special attention to the creation of complex mechanical systems with properties derived mainly from their geometric design rather than their chemical composition (Cummer et al., 2016; Bertoldi et al., 2017). Also investigated was the use of multiscale lattices to optimally design reinforcing elements for novel composite materials (Fleck et al., 2010; Li et al., 2014). The chosen modeling and experimental approaches were able to predict and characterize the intrinsically complex mechanical behavior of the analyzed systems through multiscale techniques.", "doi": "10.3389/fmats.2019.00199", "issn": "2296-8016", "publisher": "Frontiers Media SA", "publication": "Frontiers in Materials", "publication_date": "2019-08-20", "volume": "6", "pages": "Art. No. 199" }, { "id": "authors:2re6r-j4r53", "collection": "authors", "collection_id": "2re6r-j4r53", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190724-153112027", "type": "book_section", "title": "Mechanical modeling of the bandgap response of tensegrity metamaterials", "book_title": "International Conference of Numerical Analysis and Applied Mathematics", "author": [ { "family_name": "Amendola", "given_name": "Ada", "orcid": "0000-0002-2562-881X", "clpid": "Amendola-A" }, { "family_name": "Krushynska", "given_name": "Anastasiia", "orcid": "0000-0003-3259-2592", "clpid": "Krushynska-A" }, { "family_name": "De Piano", "given_name": "Mariella", "clpid": "De-Piano-M" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Pugno", "given_name": "Nicola M.", "orcid": "0000-0003-2136-2396", "clpid": "Pugno-N-M" }, { "family_name": "Fraternali", "given_name": "Fernando", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" } ], "contributor": [ { "family_name": "Simos", "given_name": "Theodore", "clpid": "Simos-T" }, { "family_name": "Tsitouras", "given_name": "Charalambos", "clpid": "Tsitouras-C" } ], "abstract": "We investigate the acoustic band structure of tensegrity mass-spring chains as a function of the applied, local and global states of prestress. We first study the bandgap response of linear monoatomic chains, which show lumped masses connected to tensegrity prisms acting as mechanical springs. Next, we present a numerical study on the nonlinear wave dynamics of the examined systems in the geometrically nonlinear regime that is induced by the presence of moderately large relative displacements between the lumped masses. Such a study confirms the results of the linear analysis in the case of an elastically hardening system.", "doi": "10.1063/1.5114261", "isbn": "978-0-7354-1854-7", "publisher": "American Institute of Physics", "place_of_publication": "Melville, NY", "publication_date": "2019-07-24", "pages": "Art. No. 260010" }, { "id": "authors:g8q6e-49c42", "collection": "authors", "collection_id": "g8q6e-49c42", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191115-142834758", "type": "article", "title": "Breathers and other time-periodic solutions in an array of cantilevers decorated with magnets", "author": [ { "family_name": "Chong", "given_name": "Christopher", "clpid": "Chong-Christopher" }, { "family_name": "Foehr", "given_name": "Andr\u00e9", "orcid": "0000-0003-0941-5424", "clpid": "Foehr-A" }, { "family_name": "Charalampidis", "given_name": "Efstathios G.", "clpid": "Charalampidis-E-G" }, { "family_name": "Kevrekidis", "given_name": "Panayotis G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In this article, the existence, stability and bifurcation structure of time-periodic solutions (including ones that also have the property of spatial localization, i.e., breathers) are studied in an array of cantilevers that have magnetic tips. The repelling magnetic tips are responsible for the intersite nonlinearity of the system, whereas the cantilevers are responsible for the onsite (potentially nonlinear) force. The relevant model is of the mixed Fermi-Pasta-Ulam-Tsingou and Klein-Gordon type with both damping and driving. In the case of base excitation, we provide experimental results to validate the model. In particular, we identify regions of bistability in the model and in the experiment, which agree with minimal tuning of the system parameters. We carry out additional numerical explorations in order to contrast the base excitation problem with the boundary excitation problem and the problem with a single mass defect. We find that the base excitation problem is more stable than the boundary excitation problem and that breathers are possible in the defect system. The effect of an onsite nonlinearity is also considered, where it is shown that bistability is possible for both softening and hardening cubic nonlinearities.", "doi": "10.3934/mine.2019.3.489", "issn": "2640-3501", "publisher": "American Institute of Mathematical Sciences", "publication": "Mathematics in Engineering", "publication_date": "2019-06-03", "series_number": "3", "volume": "1", "issue": "3", "pages": "489-507" }, { "id": "authors:4x35r-1qj39", "collection": "authors", "collection_id": "4x35r-1qj39", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190306-105123015", "type": "article", "title": "Autonomous Deployment of a Solar Panel Using an Elastic Origami and Distributed Shape Memory Polymer Actuators", "author": [ { "family_name": "Chen", "given_name": "Tian", "clpid": "Chen-Tian" }, { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-O-R" }, { "family_name": "Lang", "given_name": "Robert", "clpid": "Lang-R-J" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Shea", "given_name": "Kristina", "orcid": "0000-0003-3921-2214", "clpid": "Shea-Kristina" } ], "abstract": "We introduce a metamaterial-based self-deployable system with a rotational periodicity. As a demonstration, we propose an autonomous solar panel array that is programmed to self-deploy in response to changes in the surrounding temperature. We achieve shape reconfiguration and structural stability by exploiting the physical properties in the constituting material and the architecture of the wedge-shaped unit cell. The unit cell consists of one arm of the elastic \"flasher\" origami and a pair of scissor mechanisms. First, kinematic analysis shows the difference between the theoretical behavior and behavior considering the physical dimensions. This is used to optimize the expansion ratio. Second, the deployment mechanics are enabled through the shape-memory effect inherent in the underlying polymer. A viscoelastic constitutive model is constructed to accurately predict the self-expanding behavior. Lastly, the collapsing and deployment dynamics are discussed. Bifurcation is observed during folding, leading to two different end states, a disk or a cone. By investigating the energy landscape of the system, an apparatus is introduced to enable the disk-shaped folding. A two-stage expansion is observed during deployment. The system first rotates and then expands radially. The resulting system is three-dimensionally (3D) printed, achieves an expansion ratio of 1000% in under 40 s, and shows excellent agreement with simulation prediction both in the collapsed and expanded configurations.", "doi": "10.1103/PhysRevApplied.11.064069", "issn": "2331-7019", "publisher": "American Physical Society", "publication": "Physical Review Applied", "publication_date": "2019-06", "series_number": "6", "volume": "11", "issue": "6", "pages": "Art. No. 064069" }, { "id": "authors:mfssp-q4p59", "collection": "authors", "collection_id": "mfssp-q4p59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180817-160134182", "type": "article", "title": "Nonlinear Excitations in Magnetic Lattices with Long-Range Interactions", "author": [ { "family_name": "Moler\u00f3n", "given_name": "Miguel", "clpid": "Moler\u00f3n-M" }, { "family_name": "Chong", "given_name": "C.", "clpid": "Chong-Christopher" }, { "family_name": "Mart\u00ednez", "given_name": "Alejandro J.", "clpid": "Mart\u00ednez-A-J" }, { "family_name": "Porter", "given_name": "Mason A.", "clpid": "Porter-M-A" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study\u2014experimentally, theoretically, and numerically\u2014nonlinear excitations in lattices of magnets with long-range interactions. We examine breather solutions, which are spatially localized and periodic in time, in a chain with algebraically-decaying interactions. It was established two decades ago (Flach 1998 Phys. Rev. E 58 R4116) that lattices with long-range interactions can have breather solutions in which the spatial decay of the tails has a crossover from exponential to algebraic decay. In this article, we revisit this problem in the setting of a chain of repelling magnets with a mass defect and verify, both numerically and experimentally, the existence of breathers with such a crossover.", "doi": "10.1088/1367-2630/ab0118", "issn": "1367-2630", "publisher": "IOP", "publication": "New Journal of Physics", "publication_date": "2019-06", "series_number": "6", "volume": "21", "issue": "6", "pages": "Art. No. 063032" }, { "id": "authors:w8c9y-mhh38", "collection": "authors", "collection_id": "w8c9y-mhh38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190621-124034327", "type": "article", "title": "Nonreciprocal Wave Propagation in a Continuum-Based Metamaterial with Space-Time Modulated Resonators", "author": [ { "family_name": "Chen", "given_name": "Yangyang", "clpid": "Chen-Yangyang" }, { "family_name": "Li", "given_name": "Xiaopeng", "clpid": "Li-Xiaopeng" }, { "family_name": "Nassar", "given_name": "Hussein", "clpid": "Nassar-H" }, { "family_name": "Norris", "given_name": "Andrew N.", "clpid": "Norris-A-N" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Huang", "given_name": "Guoliang", "orcid": "0000-0002-6238-6127", "clpid": "Huang-Guoliang" } ], "abstract": "Breaking reciprocity with spatiotemporal modulation provides an opportunity to design unprecedented optical, acoustic, and mechanical waveguides. A main challenge is to physically realize continuum-based metamaterials whose properties can be rapidly tuned in both space and time at the length and time scales of the propagated waves. We design a tunable elastic metamaterial by embedding in a beam a set of permanent magnets, and placing oscillating electrical coils coaxially adjacent to each magnet. By programming in space and time the ac input of the coils, the magnet-coil effective coupling stiffness is modulated along with the resonance frequency. Distinctly nonreciprocal flexural wave propagation is then experimentally observed. In addition, robust tunability of unidirectional band gaps and wave energy bias are quantitatively analyzed by applying different modulation current amplitudes, material damping coefficients, and modulation frequencies. Both simplified analytical and finite-element-method-based numerical models of the modulated metamaterial are suggested and analyzed in support of the experimental work. Specifically, unidirectional frequency conversions and band gaps due to the second-order mode interactions are discussed for the first time when the large modulation amplitude is implemented. The suggested prototype sheds light on nonreciprocal waveguiding, which could be applied in advanced wave diodes, phononic logic, energy localization, trapping, and harvesting.", "doi": "10.1103/physrevapplied.11.064052", "issn": "2331-7019", "publisher": "American Physical Society", "publication": "Physical Review Applied", "publication_date": "2019-06", "series_number": "6", "volume": "11", "issue": "6", "pages": "Art. No. 064052" }, { "id": "authors:d5rn9-pns61", "collection": "authors", "collection_id": "d5rn9-pns61", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190212-160437905", "type": "article", "title": "Locally addressable material properties in 3D micro-architectures", "author": [ { "family_name": "Rys", "given_name": "Jan", "clpid": "Rys-J" }, { "family_name": "Steenhusen", "given_name": "S\u00f6nke", "clpid": "Steenhusen-S" }, { "family_name": "Schumacher", "given_name": "Christian", "clpid": "Schumacher-C" }, { "family_name": "Cronauer", "given_name": "Carola", "clpid": "Cronauer-C" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Heterogeneous materials with tailored, site-specific physical properties, ubiquitously found in biological systems, can reach optimal performances in applications. Compared to homogeneous materials or composite materials with random, disordered microstructures, materials with locally addressable properties achieve higher strength at lower density, or record-high shock absorption properties. A classic example of tailored, heterogeneous materials are functionally graded materials or materials where stiffness variations in bulk are controllable. However, current methods to locally control stiffness in a solid are mostly limited to geometrical variation of architected micro-structures, or to the creation of multi-material composites. Here, a novel approach to program stiffness variations within a single material system is presented. By subsequent exposure of a pre-crosslinked polymeric matrix using two-photon polymerization, arbitrary three-dimensional architectures with locally addressable stiffness variations are fabricated. Furthermore, the extension of the hierarchical level of three-dimensional micro-architectures by property variations in the constituent material is demonstrated. The programmable stiffness variations, in the sub-micron range, are either continuous or sharply confined, with a stiffness increase of up to 200% compared to the pre-crosslinked matrix. This site-specific control of stiffness and internal architecture opens the door for engineering materials with unprecedented mechanical properties.", "doi": "10.1016/j.eml.2019.02.001", "issn": "2352-4316", "publisher": "Elsevier", "publication": "Extreme Mechanics Letters", "publication_date": "2019-04", "volume": "28", "pages": "31-36" }, { "id": "authors:zzwt7-rkf36", "collection": "authors", "collection_id": "zzwt7-rkf36", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190418-122936974", "type": "article", "title": "Tuning of Surface-Acoustic-Wave Dispersion via Magnetically Modulated Contact Resonances", "author": [ { "family_name": "Palermo", "given_name": "Antonio", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-A" }, { "family_name": "Wang", "given_name": "Yifan", "orcid": "0000-0001-9965-9777", "clpid": "Wang-Yifan" }, { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-P" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In this work, we propose the use of contact resonances, controlled via an external magnetic field, as a tunable platform to manipulate the dispersion of surface acoustic waves (SAWs). We exploit the analogy between surface acoustic waves in a semi-infinite medium and edge waves in a plate, to realize a compact experimental setup and to demonstrate our tuning strategy. The setup consists of a set of ferromagnetic bead resonators in contact with thin, permanent magnets and positioned at the free edge of an elastic plate. An additional set of magnets, placed at a controlled and variable distance from the beads, is used to alter the contact stiffness and natural frequencies of the bead resonators. We exploit resonances to open large-frequency band gaps via edge-wave hybridization and implement our tuning strategy to shift their frequency ranges. We predict the tuned dispersive properties of hybridized edge waves via numerical models and experimentally reconstruct them via laser vibrometry, finding excellent agreement. The use of magnetic interaction and contact mechanics as a tuning strategy for SAW systems could pave the way toward programmable devices for sensing and electronic components.", "doi": "10.1103/PhysRevApplied.11.044057", "issn": "2331-7019", "publisher": "American Physical Society", "publication": "Physical Review Applied", "publication_date": "2019-04", "series_number": "4", "volume": "11", "issue": "4", "pages": "Art. No. 044057" }, { "id": "authors:s031b-15m39", "collection": "authors", "collection_id": "s031b-15m39", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190306-082417357", "type": "article", "title": "Bandgap widening by disorder in rainbow metamaterials", "author": [ { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-P" }, { "family_name": "Yousefzadeh", "given_name": "Behrooz", "orcid": "0000-0002-6973-717X", "clpid": "Yousefzadeh-B" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Gonella", "given_name": "Stefano", "clpid": "Gonella-S" } ], "abstract": "Stubbed plates, i.e., thin elastic sheets endowed with pillar-like resonators, display subwavelength, locally resonant bandgaps that are primarily controlled by the intrinsic resonance properties of the pillars. In this work, we experimentally study the bandgap response of a tunable heterogeneous plate endowed with reconfigurable families of pillars. We demonstrate that, under certain circumstances, both the spectrum of resonant frequencies of the pillars and their spatial arrangement influence the filtering characteristics of the system. Specifically, both spatially graded and disordered arrangements result in bandgap widening. Moreover, the spectral range over which attenuation is achieved with random arrangements is on average wider than the one observed with graded configurations.", "doi": "10.1063/1.5081916", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2019-03-04", "series_number": "9", "volume": "114", "issue": "9", "pages": "Art. No. 091903" }, { "id": "authors:7e0sn-4za47", "collection": "authors", "collection_id": "7e0sn-4za47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190306-105126503", "type": "article", "title": "Characterization of vertically aligned carbon nanotube forests grown on stainless steel surfaces", "author": [ { "family_name": "Roumeli", "given_name": "Eleftheria", "clpid": "Roumeli-Eleftheria" }, { "family_name": "Diamantopoulou", "given_name": "Marianna", "clpid": "Diamantopoulou-Marianna" }, { "family_name": "Serra-Garcia", "given_name": "Marc", "clpid": "Serra-Garcia-Marc" }, { "family_name": "Johanns", "given_name": "Paul", "orcid": "0000-0002-3093-6753", "clpid": "Johanns-Paul" }, { "family_name": "Parcianello", "given_name": "Giulio", "clpid": "Parcianello-Giulio" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Vertically aligned carbon nanotube (CNT) forests are a particularly interesting class of nanomaterials, because they combine multifunctional properties, such as high energy absorption, compressive strength, recoverability, and super-hydrophobicity with light weight. These characteristics make them suitable for application as coating, protective layers, and antifouling substrates for metallic pipelines and blades. Direct growth of CNT forests on metals offers the possibility of transferring the tunable CNT functionalities directly onto the desired substrates. Here, we focus on characterizing the structure and mechanical properties, as well as wettability and adhesion, of CNT forests grown on different types of stainless steel. We investigate the correlations between composition and morphology of the steel substrates with the micro-structure of the CNTs and reveal how the latter ultimately controls the mechanical and wetting properties of the CNT forest. Additionally, we study the influence of substrate morphology on the adhesion of CNTs to their substrate. We highlight that the same structure-property relationships govern the mechanical performance of CNT forests grown on steels and on Si.", "doi": "10.3390/nano9030444", "pmcid": "PMC6474093", "issn": "2079-4991", "publisher": "MDPI", "publication": "Nanomaterials", "publication_date": "2019-03", "series_number": "3", "volume": "9", "issue": "3", "pages": "Art. No. 444" }, { "id": "authors:khcsq-3px34", "collection": "authors", "collection_id": "khcsq-3px34", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180817-130920550", "type": "article", "title": "Shape-morphing architected sheets with non-periodic cut patterns", "author": [ { "family_name": "Celli", "given_name": "Paolo", "orcid": "0000-0001-7839-7472", "clpid": "Celli-P" }, { "family_name": "McMahan", "given_name": "Connor", "orcid": "0000-0001-5024-6138", "clpid": "McMahan-C" }, { "family_name": "Ramirez", "given_name": "Brian", "clpid": "Ramirez-B" }, { "family_name": "Bauhofer", "given_name": "Anton", "clpid": "Bauhofer-A" }, { "family_name": "Naify", "given_name": "Christina", "clpid": "Naify-C" }, { "family_name": "Hofmann", "given_name": "Douglas", "clpid": "Hofmann-D-C" }, { "family_name": "Audoly", "given_name": "Basile", "orcid": "0000-0002-0534-1467", "clpid": "Audoly-B" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate the out-of-plane shape morphing capability of single-material elastic sheets with architected cut patterns that result in arrays of tiles connected by flexible hinges. We demonstrate that a non-periodic cut pattern can cause a sheet to buckle into three-dimensional shapes, such as domes or patterns of wrinkles, when pulled at specific boundary points. These global buckling modes are observed in experiments and rationalized by an in-plane kinematic analysis that highlights the role of the geometric frustration arising from non-periodicity. The study focuses on elastic sheets, and is later extended to elastic-plastic materials to achieve shape retention. Our work illustrates a scalable route towards the fabrication of three-dimensional objects with nonzero Gaussian curvature from initially-flat sheets.", "doi": "10.1039/c8sm02082e", "issn": "1744-683X", "publisher": "Royal Society of Chemistry", "publication": "Soft Matter", "publication_date": "2018-12-28", "series_number": "48", "volume": "14", "issue": "48", "pages": "9744-9749" }, { "id": "authors:we1p4-1z689", "collection": "authors", "collection_id": "we1p4-1z689", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180820-102823309", "type": "article", "title": "Tuning frequency band gaps of tensegrity mass-spring chains with local and global prestress", "author": [ { "family_name": "Amendola", "given_name": "Ada", "orcid": "0000-0002-2562-881X", "clpid": "Amendola-A" }, { "family_name": "Krushynska", "given_name": "Anastasiia", "orcid": "0000-0003-3259-2592", "clpid": "Krushynska-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Pugno", "given_name": "Nicola M.", "orcid": "0000-0003-2136-2396", "clpid": "Pugno-N-M" }, { "family_name": "Fraternali", "given_name": "Fernando", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" } ], "abstract": "This work studies the acoustic band structure of tensegrity mass-spring chains, and the possibility to tune the dispersion relation of such systems by suitably varying local and global prestress variables. Building on established results of the Bloch\u2013Floquet theory, the paper first investigates the linearized response of chains composed of tensegrity units and lumped masses, which undergo small oscillations around an initial equilibrium state. The stiffness of the units in such a state varies with an internal self-stress induced by prestretching the cables forming the tensegrity units, and the global prestress induced by the application of compression forces to the terminal bases. The given results show that frequency band gaps of monoatomic and biatomic chains can be effectively altered by the fine tuning of local and global prestress parameters, while keeping material properties unchanged. Numerical results on the wave dynamics of chains under moderately large displacements confirm the presence of frequency band gaps of the examined systems in the elastically hardening regime. Novel engineering uses of the examined systems are discussed.", "doi": "10.1016/j.ijsolstr.2018.07.002", "issn": "0020-7683", "publisher": "Elsevier", "publication": "International Journal of Solids and Structures", "publication_date": "2018-12-15", "volume": "155", "pages": "47-56" }, { "id": "authors:pahqd-z5n91", "collection": "authors", "collection_id": "pahqd-z5n91", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180817-140020696", "type": "article", "title": "Experimental realization of on-chip topological nanoelectromechanical metamaterials", "author": [ { "family_name": "Cha", "given_name": "Jinwoong", "orcid": "0000-0002-1380-4345", "clpid": "Cha-Jinwoong" }, { "family_name": "Kim", "given_name": "Kun Woo", "clpid": "Kim-Kun-Woo" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Guiding waves through a stable physical channel is essential for reliable information transport. However, energy transport in high-frequency mechanical systems, such as in signal-processing applications, is particularly sensitive to defects and sharp turns because of back-scattering and losses. Topological phenomena in condensed matter systems have shown immunity to defects and unidirectional energy propagation. Topological mechanical metamaterials translate these properties into classical systems for efficient phononic energy transport. Acoustic and mechanical topological metamaterials have so far been realized only in large-scale systems, such as arrays of pendulums, gyroscopic lattices, structured plates and arrays of rods, cans and other structures acting as acoustic scatterers9. To fulfil their potential in device applications, mechanical topological systems need to be scaled to the on-chip level for high-frequency transport. Here we report the experimental realization of topological nanoelectromechanical metamaterials, consisting of two-dimensional arrays of free-standing silicon nitride nanomembranes that operate at high frequencies (10\u201320 megahertz). We experimentally demonstrate the presence of edge states, and characterize their localization and Dirac-cone-like frequency dispersion. Our topological waveguides are also robust to waveguide distortions and pseudospin-dependent transport. The on-chip integrated acoustic components realized here could be used in unidirectional waveguides and compact delay lines for high-frequency signal-processing applications.", "doi": "10.1038/s41586-018-0764-0", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2018-12-13", "series_number": "7735", "volume": "564", "issue": "7735", "pages": "229-233" }, { "id": "authors:xtmcg-ra706", "collection": "authors", "collection_id": "xtmcg-ra706", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180817-160149112", "type": "article", "title": "Observation of Nonreciprocal Wave Propagation in a Dynamic Phononic Lattice", "author": [ { "family_name": "Wang", "given_name": "Yifan", "orcid": "0000-0001-9965-9777", "clpid": "Wang-Yifan" }, { "family_name": "Yousefzadeh", "given_name": "Behrooz", "orcid": "0000-0002-6973-717X", "clpid": "Yousefzadeh-B" }, { "family_name": "Chen", "given_name": "Hui", "clpid": "Chen-Hui-Chen" }, { "family_name": "Nassar", "given_name": "Hussein", "clpid": "Nassar-H" }, { "family_name": "Huang", "given_name": "Guoliang", "orcid": "0000-0002-6238-6127", "clpid": "Huang-Guoliang" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Acoustic waves in a linear time-invariant medium are generally reciprocal; however, reciprocity can break down in a time-variant system. In this Letter, we report on an experimental demonstration of nonreciprocity in a dynamic one-dimensional phononic crystal, where the local elastic properties are dependent on time. The system consists of an array of repelling magnets, and the on-site elastic potentials of the constitutive elements are modulated by an array of electromagnets. The modulation in time breaks time-reversal symmetry and opens a directional band gap in the dispersion relation. As shown by experimental and numerical results, nonreciprocal mechanical systems like the one presented here offer opportunities to create phononic diodes that can serve for rectification applications.", "doi": "10.1103/PhysRevLett.121.194301", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2018-11-09", "series_number": "19", "volume": "121", "issue": "19", "pages": "Art. No. 194301" }, { "id": "authors:w26zp-03232", "collection": "authors", "collection_id": "w26zp-03232", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180731-093038705", "type": "article", "title": "Electrical tuning of elastic wave propagation in nanomechanical lattices at MHz frequencies", "author": [ { "family_name": "Cha", "given_name": "Jinwoong", "orcid": "0000-0002-1380-4345", "clpid": "Cha-Jinwoong" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Nanoelectromechanical systems (NEMS) that operate in the megahertz (MHz) regime allow energy transducibility between different physical domains. For example, they convert optical or electrical signals into mechanical motions and vice versa. This coupling of different physical quantities leads to frequency-tunable NEMS resonators via electromechanical non-linearities. NEMS platforms with single- or low-degrees of freedom have been employed to demonstrate quantum-like effects, such as mode cooling, mechanically induced transparency, Rabi oscillation, two-mode squeezing and phonon lasing. Periodic arrays of NEMS resonators with architected unit cells enable fundamental studies of lattice-based solid-state phenomena, such as bandgaps, energy transport, non-linear dynamics and localization, and topological properties, directly transferrable to on-chip devices. Here we describe one-dimensional, non-linear, nanoelectromechanical lattices (NEML) with active control of the frequency band dispersion in the radio-frequency domain (10\u201330\u2009MHz). The design of our systems is inspired by NEMS-based phonon waveguides and includes the voltage-induced frequency tuning of the individual resonators. Our NEMLs consist of a periodic arrangement of mechanically coupled, free-standing nanomembranes with circular clamped boundaries. This design forms a flexural phononic crystal with a well-defined bandgap, 1.8\u2009MHz wide. The application of a d.c. gate voltage creates voltage-dependent on-site potentials, which can significantly shift the frequency bands of the device. Additionally, a dynamic modulation of the voltage triggers non-linear effects, which induce the formation of a phononic bandgap in the acoustic branch, analogous to Peierls transition in condensed matter. The gating approach employed here makes the devices more compact than recently proposed systems, whose tunability mostly relies on materials' compliance and mechanical non-linearities.", "doi": "10.1038/s41565-018-0252-6", "issn": "1748-3387", "publisher": "Nature Publishing Group", "publication": "Nature Nanotechnology", "publication_date": "2018-11", "series_number": "11", "volume": "13", "issue": "11", "pages": "1016-1020" }, { "id": "authors:1d1gb-q4w06", "collection": "authors", "collection_id": "1d1gb-q4w06", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181212-123259440", "type": "article", "title": "Architected Lattices for Simultaneous Broadband Attenuation of Airborne Sound and Mechanical Vibrations in All Directions", "author": [ { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-O-R" }, { "family_name": "Ballagi", "given_name": "David", "clpid": "Ballagi-D" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Phononic crystals and acoustic metamaterials are architected lattices designed to control the propagation of acoustic or elastic waves. In these materials, the dispersion properties and the energy transfer are controlled by selecting the geometry of the lattices and their constitutive material properties. Most designs, however, only affect one mode of energy propagation, transmitted either as acoustic airborne sound or as elastic structural vibrations. Here, we present a design methodology to attenuate both acoustic and elastic waves simultaneously in all polarizations. We experimentally realize a three-dimensional load-bearing architected lattice, composed of a single material, that responds in a broadband frequency range in all directions and polarizations for airborne sound and elastic vibrations simultaneously.", "doi": "10.1103/PhysRevApplied.10.054060", "issn": "2331-7019", "publisher": "American Physical Society", "publication": "Physical Review Applied", "publication_date": "2018-11", "series_number": "5", "volume": "10", "issue": "5", "pages": "Art. No. 054060" }, { "id": "authors:n8cp4-q5c14", "collection": "authors", "collection_id": "n8cp4-q5c14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180620-111804620", "type": "article", "title": "Highly Porous Microlattices as Ultrathin and Efficient Impact Absorbers", "author": [ { "family_name": "Lai", "given_name": "Chang Quan", "clpid": "Lai-Chang-Quan" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The deformation and impact energy absorption properties of ultrathin polymeric microlattices were investigated as a function of density, size and positional eccentricity of the trusses, which controlled the amount of bending in the microlattice deformations. We considered highly porous, 3-D microstructures with small lattice constants (\u2264 135 \u03bcm), and studied their response to high strain rate (\u223c1000/s) tests, using high speed video capture, SEM imaging and quantitative modelling. The microlattices were found to have excellent impact absorption efficiencies that are 2 - 120 times better than carbon nanotube foams, polycarbonate and silicone rubber, despite being an order of magnitude slimmer than the thinnest commercial foams of similar densities. This high impact absorption efficiency is largely due to the sideways buckling of the microlattice trusses during the crushing stage, which prevented densification of the microlattices at small strains. Furthermore, we showed that varying the positional eccentricity of the trusses and the number of unit cells in the microlattices can modulate their stiffness, strength and energy absorption over an appreciable range, comparable to that obtained through modifications in relative density. Because the microlattices were mostly under stress equilibrium during the impact process, the insights derived from the present study are expected to be valid for quasistatic and low strain rate loadings as well.", "doi": "10.1016/j.ijimpeng.2018.05.014", "issn": "0734-743X", "publisher": "Elsevier", "publication": "International Journal of Impact Engineering", "publication_date": "2018-10", "volume": "120", "pages": "138-149" }, { "id": "authors:wpgz6-2w738", "collection": "authors", "collection_id": "wpgz6-2w738", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190606-072050998", "type": "book_section", "title": "Resonant metabarriers as seismic attenuators in granular media", "book_title": "Proceedings of International Conference on Noise and Vibration Engineering (ISMA2018) / International Conference on Uncertainty in Structural Dynamics (USD2018)", "author": [ { "family_name": "Zaccherini", "given_name": "R.", "clpid": "Zaccherini-R" }, { "family_name": "Palermo", "given_name": "A.", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-A" }, { "family_name": "Kr\u00f6del", "given_name": "S.", "orcid": "0000-0002-9218-8578", "clpid": "Kr\u00f6del-S" }, { "family_name": "Dertimanis", "given_name": "V. K.", "clpid": "Dertimanis-V-K" }, { "family_name": "Marzani", "given_name": "A.", "clpid": "Marzani-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Chatzi", "given_name": "E. N.", "clpid": "Chatzi-E-N" } ], "contributor": [ { "family_name": "Desmet", "given_name": "W.", "clpid": "Desmet-W" }, { "family_name": "Pluymers", "given_name": "B.", "clpid": "Pluymers-B" }, { "family_name": "Moens", "given_name": "D.", "clpid": "Moens-D" }, { "family_name": "Rottiers", "given_name": "W.", "clpid": "Rottiers-W" } ], "abstract": "Arrays of surface resonators forming so-called metabarriers are capable of converting seismic Rayleigh waves into less dangerous shear waves traveling in the bulk, attenuating the ground motion at the surface. However, this phenomenon pertains to resonant materials inserted in homogeneous media which feature properties rather different to those of natural soils. In this work, we experimentally investigate the ability of a resonant metabarrier embedded below the surface of an inhomogenous medium, i.e. a granular unconsolidated material, to attenuate the incoming surface waves. Although unable to diverge their propagation into the bulk, we find that surface resonators in granular media achieve attenuation of Rayleigh waves by up to 50 % around their resonant frequency. The findings can be used as a starting point for future real-scale implementations for seismic protection systems in stratified soils presenting an inhomogeneous stiffness profile at the seismic Rayleigh waves scale.", "isbn": "978-90-73802-99-5", "publisher": "Katholieke Universiteit Leuven", "place_of_publication": "Heverlee, Belgium", "publication_date": "2018-09", "pages": "3047-3057" }, { "id": "authors:pqf23-rac87", "collection": "authors", "collection_id": "pqf23-rac87", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181127-074145554", "type": "book_section", "title": "Tunable extremely wide low-frequency band gaps in accordion-like metamaterials", "book_title": "2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials)", "author": [ { "family_name": "Krushynska", "given_name": "A. O.", "orcid": "0000-0003-3259-2592", "clpid": "Krushynska-A-O" }, { "family_name": "Amendola", "given_name": "A.", "orcid": "0000-0002-2562-881X", "clpid": "Amendola-A" }, { "family_name": "Bosia", "given_name": "F.", "orcid": "0000-0002-2886-4519", "clpid": "Bosia-F" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Pugno", "given_name": "N. M.", "orcid": "0000-0003-2136-2396", "clpid": "Pugno-N-M" }, { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" } ], "abstract": "To achieve wave control at broad-band ultra-low frequencies, we design \"accordion-like\" meta-structures by periodically alternating tensegrity prisms with solid disks. The structures are characterized by extremely wide band gaps, which can be tuned by varying the level of prestress in the constituent elements. They provide valid alternatives to other metamaterials with low-frequency performance, the functionality of which relies on a locally resonant mechanism, by overcoming an inherent limit of narrow operating frequency ranges and demonstrating the resilience to variations in geometric and material parameters.", "doi": "10.1109/MetaMaterials.2018.8534115", "isbn": "978-1-5386-4702-8", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2018-09", "pages": "237-239" }, { "id": "authors:7mpx8-sfs04", "collection": "authors", "collection_id": "7mpx8-sfs04", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180725-141033498", "type": "article", "title": "Tunable, synchronized frequency down-conversion in magnetic lattices with defects", "author": [ { "family_name": "Serra-Garcia", "given_name": "Marc", "clpid": "Serra-Garcia-Marc" }, { "family_name": "Moler\u00f3n", "given_name": "Miguel", "clpid": "Moler\u00f3n-Miguel" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study frequency conversion in nonlinear mechanical lattices, focusing on a chain of magnets as a model system. We show that, by inserting mass defects at suitable locations, we can introduce localized vibrational modes that nonlinearly couple to extended lattice modes. The nonlinear interaction introduces an energy transfer from the high-frequency localized modes to a low-frequency extended mode. This system is capable of autonomously converting energy between highly tunable input and output frequencies, which need not be related by integer harmonic or subharmonic ratios. It is also capable of obtaining energy from multiple sources at different frequencies with a tunable output phase, due to the defect synchronization provided by the extended mode. Our lattice is a purely mechanical analogue of an opto-mechanical system, where the localized modes play the role of the electromagnetic field and the extended mode plays the role of the mechanical degree of freedom.", "doi": "10.1098/rsta.2017.0137", "pmcid": "PMC6077864", "issn": "0080-4614", "publisher": "Royal Society", "publication": "Philosophical transactions of the Royal Society of London. Series A: Mathematical and physical sciences", "publication_date": "2018-08-28", "series_number": "2127", "volume": "376", "issue": "2127", "pages": "Art. No. 20170137" }, { "id": "authors:0jqwd-c8v30", "collection": "authors", "collection_id": "0jqwd-c8v30", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180808-142444401", "type": "article", "title": "Design of Engineered Elastomeric Substrate for Stretchable Active Devices and Sensors", "author": [ { "family_name": "Cantarella", "given_name": "Giuseppe", "orcid": "0000-0002-6398-601X", "clpid": "Cantarella-G" }, { "family_name": "Costanza", "given_name": "Vincenzo", "orcid": "0000-0002-2409-0632", "clpid": "Costanza-V" }, { "family_name": "Ferrero", "given_name": "Alberto", "clpid": "Ferrero-A" }, { "family_name": "Hopf", "given_name": "Raoul", "clpid": "Hopf-R" }, { "family_name": "Vogt", "given_name": "Christian", "clpid": "Vogt-C" }, { "family_name": "Varga", "given_name": "Matija", "clpid": "Varga-M" }, { "family_name": "Petti", "given_name": "Luisa", "clpid": "Petti-L" }, { "family_name": "M\u00fcnzenrieder", "given_name": "Niko", "clpid": "M\u00fcnzenrieder-N" }, { "family_name": "B\u00fcthe", "given_name": "Lars", "clpid": "B\u00fcthe-L" }, { "family_name": "Salvatore", "given_name": "Giovanni", "clpid": "Salvatore-G" }, { "family_name": "Claville", "given_name": "Alex", "clpid": "Claville-A" }, { "family_name": "Bonanomi", "given_name": "Luca", "clpid": "Bonanomi-L" }, { "family_name": "Daus", "given_name": "Alwin", "clpid": "Daus-A" }, { "family_name": "Knobelspies", "given_name": "Stefan", "clpid": "Knobelspies-S" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Tr\u00f6ster", "given_name": "Gerhard", "clpid": "Tr\u00f6ster-G" } ], "abstract": "In the field of flexible electronics, emerging applications require biocompatible and unobtrusive devices, which can withstand different modes of mechanical deformation and achieve low complexity in the fabrication process. Here, the fabrication of a mesa\u2010shaped elastomeric substrate, supporting thin\u2010film transistors (TFTs) and logic circuits (inverters), is reported. High\u2010relief structures are designed to minimize the strain experienced by the electronics, which are fabricated directly on the pillars' surface. In this design configuration, devices based on amorphous indium\u2010gallium\u2010zinc\u2010oxide can withstand different modes of deformation. Bending, stretching, and twisting experiments up to 6 mm radius, 20% uniaxial strain, and 180\u00b0 global twisting, respectively, are performed to show stable electrical performance of the TFTs. Similarly, a fully integrated digital inverter is tested while stretched up to 20% elongation. As a proof of the versatility of mesa\u2010shaped geometry, a biocompatible and stretchable sensor for temperature mapping is also realized. Using pectin, which is a temperature\u2010sensitive material present in plant cells, the response of the sensor shows current modulation from 13 to 28 \u00b0C and functionality up to 15% strain. These results demonstrate the performance of highly flexible electronics for a broad variety of applications, including smart skin and health monitoring.", "doi": "10.1002/adfm.201705132", "issn": "1616-301X", "publisher": "Wiley", "publication": "Advanced Functional Materials", "publication_date": "2018-07-25", "series_number": "30", "volume": "28", "issue": "30", "pages": "Art. No. 1705132" }, { "id": "authors:k9w1j-88k96", "collection": "authors", "collection_id": "k9w1j-88k96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180724-125220277", "type": "article", "title": "Acoustic properties of porous microlattices from effective medium to scattering dominated regimes", "author": [ { "family_name": "Kr\u00f6del", "given_name": "Sebastian", "orcid": "0000-0002-9218-8578", "clpid": "Kr\u00f6del-S" }, { "family_name": "Palermo", "given_name": "Antonio", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Microlattices are architected materials that allow for an unprecedented control of mechanical properties (e.g., stiffness, density, and Poisson's coefficient). In contrast to their quasi-static mechanical properties, the acoustic properties of microlattices remain largely unexplored. This paper analyzes the acoustic response of periodic millimeter-sized microlattices immersed in water using experiments and numerical simulations. Microlattices are fabricated using high-precision stereolithographic three-dimensional printing in a large variety of porosities and lattice topologies. This paper shows that the acoustic propagation undergoes a frequency dependent transition from a classic poroelastic behaviour that can be described by Biot's theory to a regime that is dominated by scattering effects. Biot's acoustic parameters are derived from direct simulations of the microstructure using coupled fluid and solid finite elements. The wave speeds predicted with Biot's theory agree well with the experimental measures. Within the scattering regime, the signals show a strong attenuation and dispersion, which is characterized by a cut-off frequency. The strong dispersion results in a frequency dependent group velocity. A simplified model of an elastic cylindrical scatterer allows predicting the signal attenuation and dispersion observed experimentally. The results in this paper pave the way for the creation of microlattice materials for the control of ultrasonic waves across a wide range of frequencies.", "doi": "10.1121/1.5046068", "issn": "0001-4966", "publisher": "Acoustical Society of America", "publication": "Journal of the Acoustical Society of America", "publication_date": "2018-07", "series_number": "1", "volume": "144", "issue": "1", "pages": "319-329" }, { "id": "authors:4d3cx-0zk91", "collection": "authors", "collection_id": "4d3cx-0zk91", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180816-073517360", "type": "article", "title": "Accordion-like metamaterials with tunable ultra-wide low-frequency band gaps", "author": [ { "family_name": "Krushynska", "given_name": "A. O.", "orcid": "0000-0003-3259-2592", "clpid": "Krushynska-A-O" }, { "family_name": "Amendola", "given_name": "A.", "orcid": "0000-0002-2562-881X", "clpid": "Amendola-A" }, { "family_name": "Bosia", "given_name": "F.", "orcid": "0000-0002-2886-4519", "clpid": "Bosia-F" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Pugno", "given_name": "N. M.", "orcid": "0000-0003-2136-2396", "clpid": "Pugno-N-M" }, { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" } ], "abstract": "Composite materials with engineered band gaps are promising solutions for wave control and vibration mitigation at various frequency scales. Despite recent advances in the design of phononic crystals and acoustic metamaterials, the generation of wide low-frequency band gaps in practically feasible configurations remains a challenge. Here, we present a class of lightweight metamaterials capable of strongly attenuating low-frequency elastic waves, and investigate this behavior by numerical simulations. For their realization, tensegrity prisms are alternated with solid discs in periodic arrangements that we call 'accordion-like' meta-structures. They are characterized by extremely wide band gaps and uniform wave attenuation at low frequencies that distinguish them from existing designs with limited performance at low-frequencies or excessively large sizes. To achieve these properties, the meta-structures exploit Bragg and local resonance mechanisms together with decoupling of translational and bending modes. This combination allows one to implement selective control of the pass and gap frequencies and to reduce the number of structural modes. We demonstrate that the meta-structural attenuation performance is insensitive to variations of geometric and material properties and can be tuned by varying the level of prestress in the tensegrity units. The developed design concept is an elegant solution that could be of use in impact protection, vibration mitigation, or noise control under strict weight limitations.", "doi": "10.1088/1367-2630/aad354", "issn": "1367-2630", "publisher": "IOP", "publication": "New Journal of Physics", "publication_date": "2018-07", "series_number": "7", "volume": "20", "issue": "7", "pages": "Art. No. 073051" }, { "id": "authors:wqtea-v9h11", "collection": "authors", "collection_id": "wqtea-v9h11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180515-101708023", "type": "article", "title": "Harnessing bistability for directional propulsion of soft, untethered robots", "author": [ { "family_name": "Chen", "given_name": "Tian", "clpid": "Chen-Tian" }, { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-Osama-R" }, { "family_name": "Shea", "given_name": "Kristina", "orcid": "0000-0003-3921-2214", "clpid": "Shea-Kristina" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In most macroscale robotic systems, propulsion and controls are enabled through a physical tether or complex onboard electronics and batteries. A tether simplifies the design process but limits the range of motion of the robot, while onboard controls and power supplies are heavy and complicate the design process. Here, we present a simple design principle for an untethered, soft swimming robot with preprogrammed, directional propulsion without a battery or onboard electronics. Locomotion is achieved by using actuators that harness the large displacements of bistable elements triggered by surrounding temperature changes. Powered by shape memory polymer (SMP) muscles, the bistable elements in turn actuate the robot's fins. Our robots are fabricated using a commercially available 3D printer in a single print. As a proof of concept, we show the ability to program a vessel, which can autonomously deliver a cargo and navigate back to the deployment point.", "doi": "10.1073/pnas.1800386115", "pmcid": "PMC5984517", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2018-05-29", "series_number": "22", "volume": "115", "issue": "22", "pages": "5698-5702" }, { "id": "authors:p1ngf-gc345", "collection": "authors", "collection_id": "p1ngf-gc345", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180515-145438902", "type": "article", "title": "Spiral-Based Phononic Plates: From Wave Beaming to Topological Insulators", "author": [ { "family_name": "Foehr", "given_name": "Andr\u00e9", "orcid": "0000-0003-0941-5424", "clpid": "Foehr-A" }, { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-O-R" }, { "family_name": "Huber", "given_name": "Sebastian D.", "orcid": "0000-0003-3558-351X", "clpid": "Huber-S-D" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Phononic crystals and metamaterials can sculpt elastic waves, controlling their dispersion using different mechanisms. These mechanisms are mostly Bragg scattering, local resonances, and inertial amplification, derived from ad hoc, often problem-specific geometries of the materials' building blocks. Here, we present a platform that ultilizes a lattice of spiraling unit cells to create phononic materials encompassing Bragg scattering, local resonances, and inertial amplification. We present two examples of phononic materials that can control waves with wavelengths much larger than the lattice's periodicity. (1) A wave beaming plate, which can beam waves at arbitrary angles, independent of the lattice vectors. We show that the beaming trajectory can be continuously tuned, by varying the driving frequency or the spirals' orientation. (2) A topological insulator plate, which derives its properties from a resonance-based Dirac cone below the Bragg limit of the structured lattice of spirals.", "doi": "10.1103/PhysRevLett.120.205501", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2018-05-18", "series_number": "20", "volume": "120", "issue": "20", "pages": "Art. No. 205501" }, { "id": "authors:q0k1q-87x43", "collection": "authors", "collection_id": "q0k1q-87x43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180517-100308712", "type": "article", "title": "Hybridization of Guided Surface Acoustic Modes in Unconsolidated Granular Media by a Resonant Metasurface", "author": [ { "family_name": "Palermo", "given_name": "Antonio", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-A" }, { "family_name": "Kr\u00f6del", "given_name": "Sebastian", "orcid": "0000-0002-9218-8578", "clpid": "Kr\u00f6del-S" }, { "family_name": "Matlack", "given_name": "Kathryn H.", "orcid": "0000-0001-7387-2414", "clpid": "Matlack-K-H" }, { "family_name": "Zaccherini", "given_name": "Rachele", "clpid": "Zaccherini-R" }, { "family_name": "Dertimanis", "given_name": "Vasilis K.", "clpid": "Dertimanis-V-K" }, { "family_name": "Chatzi", "given_name": "Eleni N.", "clpid": "Chatzi-E-N" }, { "family_name": "Marzani", "given_name": "Alessandro", "clpid": "Marzani-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate the interaction of guided surface acoustic modes (GSAMs) in unconsolidated granular media with a metasurface, consisting of an array of vertical oscillators. We experimentally observe the hybridization of the lowest-order GSAM at the metasurface resonance, and note the absence of mode delocalization found in homogeneous media. Our numerical studies reveal how the stiffness gradient induced by gravity in granular media causes a down-conversion of all the higher-order GSAMs, which preserves the acoustic energy confinement. We anticipate these findings to have implications in the design of seismic-wave protection devices in stratified soils.", "doi": "10.1103/PhysRevApplied.9.054026", "issn": "2331-7019", "publisher": "American Physical Society", "publication": "Physical Review Applied", "publication_date": "2018-05", "series_number": "5", "volume": "9", "issue": "5", "pages": "Art. No. 054026" }, { "id": "authors:wzag7-0wz75", "collection": "authors", "collection_id": "wzag7-0wz75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171115-144804382", "type": "article", "title": "Designing perturbative metamaterials from discrete models", "author": [ { "family_name": "Matlack", "given_name": "Kathryn H.", "orcid": "0000-0001-7387-2414", "clpid": "Matlack-K-H" }, { "family_name": "Serra-Garcia", "given_name": "Marc", "clpid": "Serra-Garcia-M" }, { "family_name": "Palermo", "given_name": "Antonio", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-A" }, { "family_name": "Huber", "given_name": "Sebastian D.", "orcid": "0000-0003-3558-351X", "clpid": "Huber-S-D" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Identifying material geometries that lead to metamaterials with desired functionalities presents a challenge for the field. Discrete, or reduced-order, models provide a concise description of complex phenomena, such as negative refraction, or topological surface states; therefore, the combination of geometric building blocks to replicate discrete models presenting the desired features represents a promising approach. However, there is no reliable way to solve such an inverse problem. Here, we introduce 'perturbative metamaterials', a class of metamaterials consisting of weakly interacting unit cells. The weak interaction allows us to associate each element of the discrete model with individual geometric features of the metamaterial, thereby enabling a systematic design process. We demonstrate our approach by designing two-dimensional elastic metamaterials that realize Veselago lenses, zero-dispersion bands and topological surface phonons. While our selected examples are within the mechanical domain, the same design principle can be applied to acoustic, thermal and photonic metamaterials composed of weakly interacting unit cells.", "doi": "10.1038/s41563-017-0003-3", "issn": "1476-1122", "publisher": "Nature Publishing Group", "publication": "Nature Materials", "publication_date": "2018-04", "series_number": "4", "volume": "17", "issue": "4", "pages": "323-328" }, { "id": "authors:cx124-m6686", "collection": "authors", "collection_id": "cx124-m6686", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180817-160141057", "type": "monograph", "title": "Tuning frequency band gaps of tensegrity metamaterials with local and global prestress", "author": [ { "family_name": "Amendola", "given_name": "Ada", "orcid": "0000-0002-2562-881X", "clpid": "Amendola-A" }, { "family_name": "Krushynska", "given_name": "Anastasiia", "orcid": "0000-0003-3259-2592", "clpid": "Krushynska-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Pugno", "given_name": "Nicola M.", "orcid": "0000-0003-2136-2396", "clpid": "Pugno-N-M" }, { "family_name": "Fraternali", "given_name": "Fernando", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" } ], "abstract": "This work studies the acoustic band structure of tensegrity metamaterials, and the possibility to tune the dispersion relation of such systems by playing with local and global prestress variables. Building on established results of the Bloch-Floquet theory, the paper first investigates the linearized response of chains composed of tensegrity units and lumped masses, which undergo small oscillations around an initial equilibrium state. The stiffness of the units in such a state varies with an internal self-stress induced by prestretching the cables forming the tensegrity units, and the global prestress induced by the application of compression forces to the terminal bases. The given results show that frequency band gaps of monoatomic and biatomic chains can be effectively altered by the fine tuning of local and global prestress parameters, while keeping material properties unchanged. Numerical results on the wave dynamics of chains under moderately large displacements confirm the presence of frequency band gaps of the examined systems in the elastically hardening regime. Novel engineering uses of the examined metamaterials are discussed.", "doi": "10.48550/arXiv.1803.03472", "publisher": "arXiv", "publication_date": "2018-03-09" }, { "id": "authors:kqtm7-tmv72", "collection": "authors", "collection_id": "kqtm7-tmv72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171031-072946861", "type": "article", "title": "Direct observation of impact propagation and absorption in dense colloidal monolayers", "author": [ { "family_name": "Buttinoni", "given_name": "Ivo", "clpid": "Buttinoni-Ivo" }, { "family_name": "Cha", "given_name": "Jinwoong", "orcid": "0000-0002-1380-4345", "clpid": "Cha-Jinwoong" }, { "family_name": "Lin", "given_name": "Wei-Hsun", "clpid": "Lin-Wei-Hsun" }, { "family_name": "Job", "given_name": "St\u00e9phane", "clpid": "Job-St\u00e9phane" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Isa", "given_name": "Lucio", "clpid": "Isa-Lucio" } ], "abstract": "Dense colloidal suspensions can propagate and absorb large mechanical stresses, including impacts and shocks. The wave transport stems from the delicate interplay between the spatial arrangement of the structural units and solvent-mediated effects. For dynamic microscopic systems, elastic deformations of the colloids are usually disregarded due to the damping imposed by the surrounding fluid. Here, we study the propagation of localized mechanical pulses in aqueous monolayers of micron-sized particles of controlled microstructure. We generate extreme localized deformation rates by exciting a target particle via pulsed-laser ablation. In crystalline monolayers, stress propagation fronts take place, where fast-moving particles (V approximately a few meters per second) are aligned along the symmetry axes of the lattice. Conversely, more viscous solvents and disordered structures lead to faster and isotropic energy absorption. Our results demonstrate the accessibility of a regime where elastic collisions also become relevant for suspensions of microscopic particles, behaving as \"billiard balls\" in a liquid, in analogy with regular packings of macroscopic spheres. We furthermore quantify the scattering of an impact as a function of the local structural disorder.", "doi": "10.1073/pnas.1712266114", "pmcid": "PMC5699069", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2017-11-14", "series_number": "46", "volume": "114", "issue": "46", "pages": "12150-12155" }, { "id": "authors:v7y8a-jat22", "collection": "authors", "collection_id": "v7y8a-jat22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170925-104553545", "type": "article", "title": "Harnessing Photochemical Shrinkage in Direct Laser Writing for Shape Morphing of Polymer Sheets", "author": [ { "family_name": "Bauhofer", "given_name": "Anton A.", "clpid": "Bauhofer-A-A" }, { "family_name": "Kr\u00f6del", "given_name": "Sebastian", "orcid": "0000-0002-9218-8578", "clpid": "Kr\u00f6del-S" }, { "family_name": "Rys", "given_name": "Jan", "clpid": "Rys-J" }, { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-O-R" }, { "family_name": "Constantinescu", "given_name": "Andrei", "clpid": "Constantinescu-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Structures that change their shape in response to external stimuli unfold possibilities for more efficient and versatile production of 3D objects. Direct laser writing (DLW) is a technique based on two-photon polymerization that allows the fabrication of microstructures with complex 3D geometries. Here, it is shown that polymerization shrinkage in DLW can be utilized to create structures with locally controllable residual stresses that enable programmable, self-bending behavior. To demonstrate this concept, planar and 3D-structured sheets are preprogrammed to evolve into bio-inspired shapes (lotus flowers and shark skins). The fundamental mechanisms that control the self-bending behavior are identified and tested with microscale experiments. Based on the findings, an analytical model is introduced to quantitatively predict bending curvatures of the fabricated sheets. The proposed method enables simple fabrication of objects with complex geometries and precisely controllable shape morphing potential, while drastically reducing the required fabrication times for producing 3D, hierarchical microstructures over large areas in the order of square centimeters.", "doi": "10.1002/adma.201703024", "issn": "0935-9648", "publisher": "Wiley", "publication": "Advanced Materials", "publication_date": "2017-11-13", "series_number": "42", "volume": "29", "issue": "42", "pages": "Art. No. 1703024" }, { "id": "authors:hse84-05673", "collection": "authors", "collection_id": "hse84-05673", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170906-154802672", "type": "article", "title": "Nonlinear coherent structures in granular crystals", "author": [ { "family_name": "Chong", "given_name": "C.", "clpid": "Chong-Christopher" }, { "family_name": "Porter", "given_name": "Mason A.", "orcid": "0000-0002-5166-0717", "clpid": "Porter-Mason-A" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-Panayotis-G" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The study of granular crystals, which are nonlinear metamaterials that consist of closely packed arrays of particles that interact elastically, is a vibrant area of research that combines ideas from disciplines such as materials science, nonlinear dynamics, and condensed-matter physics. Granular crystals exploit geometrical nonlinearities in their constitutive microstructure to produce properties (such as tunability and energy localization) that are not conventional to engineering materials and linear devices. In this topical review, we focus on recent experimental, computational, and theoretical results on nonlinear coherent structures in granular crystals. Such structures\u2014which include traveling solitary waves, dispersive shock waves, and discrete breathers\u2014have fascinating dynamics, including a diversity of both transient features and robust, long-lived patterns that emerge from broad classes of initial data. In our review, we primarily discuss phenomena in one-dimensional crystals, as most research to date has focused on such scenarios, but we also present some extensions to two-dimensional settings. Throughout the review, we highlight open problems and discuss a variety of potential engineering applications that arise from the rich dynamic response of granular crystals.", "doi": "10.1088/1361-648X/aa7672", "issn": "0953-8984", "publisher": "IOP", "publication": "Journal of Physics: Condensed Matter", "publication_date": "2017-10-18", "series_number": "41", "volume": "29", "issue": "41", "pages": "Art. No. 413003" }, { "id": "authors:b1s1k-2nz57", "collection": "authors", "collection_id": "b1s1k-2nz57", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170828-123658047", "type": "article", "title": "Reprogrammable Phononic Metasurfaces", "author": [ { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-O-R" }, { "family_name": "Foehr", "given_name": "Andr\u00e9", "orcid": "0000-0003-0941-5424", "clpid": "Foehr-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Phononic metamaterials rely on the presence of resonances in a structured medium to control the propagation of elastic waves. Their response depends on the geometry of their fundamental building blocks. A major challenge in metamaterials design is the realization of basic building blocks that can be tuned dynamically. Here, a metamaterial plate is realized that can be dynamically tuned by harnessing geometric and magnetic nonlinearities in the individual unit cells. The proposed tuning mechanism allows a stiffness variability of the individual unit cells and can control the amplitude of transmitted excitation through the plate over three orders of magnitude. The concepts can be extended to metamaterials at different scales, and they can be applied in a broad range of engineering applications, from seismic shielding at low frequency to ultrasonic cloaking at higher frequency ranges.", "doi": "10.1002/adma.201700628", "issn": "0935-9648", "publisher": "Wiley", "publication": "Advanced Materials", "publication_date": "2017-10-18", "series_number": "39", "volume": "29", "issue": "39", "pages": "Art. No. 1700628" }, { "id": "authors:smns7-r2j04", "collection": "authors", "collection_id": "smns7-r2j04", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171030-161132167", "type": "article", "title": "Complete delocalization in a defective periodic structure", "author": [ { "family_name": "Yousefzadeh", "given_name": "Behrooz", "orcid": "0000-0002-6973-717X", "clpid": "Yousefzadeh-B" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We report on the existence of stable, completely delocalized response regimes in a nonlinear defective periodic structure. In this state of complete delocalization, despite the presence of the defect, the system exhibits in-phase oscillation of all units with the same amplitude. This elimination of defect-borne localization may occur in both the free and forced responses of the system. In the absence of external driving, the localized defect mode becomes completely delocalized at a certain energy level. In the case of a damped-driven system, complete delocalization may be realized if the driving amplitude is beyond a certain threshold. We demonstrate this phenomenon numerically in a linear periodic structure with one and two defective units possessing a nonlinear restoring force. We derive closed-form analytical expressions for the onset of complete delocalization, and we discuss the necessary conditions for its occurrence.", "doi": "10.1103/PhysRevE.96.042219", "issn": "2470-0045", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2017-10", "series_number": "4", "volume": "96", "issue": "4", "pages": "Art. No. 042219" }, { "id": "authors:evf3m-5tz66", "collection": "authors", "collection_id": "evf3m-5tz66", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170628-161000911", "type": "article", "title": "Stress relaxation in polymeric microlattice materials", "author": [ { "family_name": "Kr\u00f6del", "given_name": "Sebastian", "orcid": "0000-0002-9218-8578", "clpid": "Kr\u00f6del-S" }, { "family_name": "Li", "given_name": "Lichen", "clpid": "Li-Lichen" }, { "family_name": "Constantinescu", "given_name": "Andrei", "clpid": "Constantinescu-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Breakthroughs in fabrication techniques enabled the creation of microlattice materials, which are assembled from truss-like elements on the micro-scale. The mechanical properties of these materials can be controlled varying the geometry of their microstructure. Here, we study the effect of topology and effective density on the visco-elastic properties of microlattices fabricated by direct laser writing. We perform micro scale relaxation experiments using capacitive force sensing in compression. The experimental results are analyzed using a generalized Maxwell model and the viscoelastic properties are studied in terms of density scaling laws. We develop a finite element model that allows extracting the bulk polymer viscoelastic properties. The experimental results show that the stiffness of lattice materials can be adjusted independently from the loss factor in a wide range of frequencies. We find that the loss factor dramatically increases with applied strain due to the onset of nonlinear dissipation mechanism such as buckling and plasticity. We show that at effective densities around 50% the energy dissipation per cycle in a microlattice outperforms the dissipation in the bulk, giving rise to a \"less is more\" effect. The present research defines a first step in the application of microlattice materials in vibration absorption.", "doi": "10.1016/j.matdes.2017.05.060", "issn": "0264-1275", "publisher": "Elsevier", "publication": "Materials and Design", "publication_date": "2017-09-15", "volume": "130", "pages": "433-441" }, { "id": "authors:eepbc-sv971", "collection": "authors", "collection_id": "eepbc-sv971", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170707-090848267", "type": "article", "title": "Observation of trampoline phenomena in 3D-printed metamaterial plates", "author": [ { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-O-R" }, { "family_name": "Foehr", "given_name": "Andr\u00e9", "orcid": "0000-0003-0941-5424", "clpid": "Foehr-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Two dimensional phononic metamaterials, consisting of plates with resonant cylinders have been shown to attenuate waves much larger than their characteristic unit cell size by opening subwavelength band gaps. However the bandwidth of the gap correlates strongly with the resonator mass, which limits metamaterials functionality in mass sensitive applications. Trampoline phenomena have theoretically been shown to broaden the width of the first partial band gap by up to a factor 4 of the linear, resonant band gap. In this work, we provide an experimental demonstration of the trampoline phenomena in 3D-printed plates, consisting of pillars and holes, composed of a single material . We observe the opening of significant locally resonant band gaps, \u2248 30% normalized width, without adding any significant mass to the homogeneous plate. We show numerically and experimentally that trampoline plates increase both partial and full band gaps width, while reducing the base-plate's mass by \u224830% in the studied configurations.", "doi": "10.1016/j.eml.2017.06.004", "issn": "2352-4316", "publisher": "Elsevier", "publication": "Extreme Mechanics Letters", "publication_date": "2017-09", "volume": "15", "pages": "103-107" }, { "id": "authors:dn7be-cp618", "collection": "authors", "collection_id": "dn7be-cp618", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180215-140456213", "type": "book_section", "title": "Non-Reciprocity in Structures With Nonlinear Internal Hierarchy and Asymmetry", "book_title": "ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference", "author": [ { "family_name": "Fronk", "given_name": "Matthew D.", "clpid": "Fronk-M-D" }, { "family_name": "Tawfick", "given_name": "Sameh", "clpid": "Tawfick-S" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Vakakis", "given_name": "Alexander F.", "clpid": "Vakakis-A-F" }, { "family_name": "Leamy", "given_name": "Michael J.", "clpid": "Leamy-M-J" } ], "abstract": "Acoustic reciprocity is a property of linear, time invariant systems in which the locations of the source of a forcing and the received signal can be interchanged with no change in the measured response. This work investigates the breaking of acoustic reciprocity using a hierarchical structure consisting of internally-scaled masses coupled with cubically nonlinear springs. Using both direct results and variable transformations of numerical simulations, energy transmission is shown to occur in the direction of decreasing scale but not vice versa, constituting the breaking of acoustic reciprocity locally. When a linear spring connects the smallest scale of such a structure to the largest scale of another identical structure, an asymmetrical lattice is formed. Because of the scale mixing and transient resonance capture that occurs within each unit cell, it is demonstrated through further numerical experiments that energy transmission occurs primarily in the direction associated with the nonlinear coupling from the large to the small scale, thus signifying the breaking of reciprocity globally. This nonlinear hierarchical structure exhibits strong amplitude-dependency in which reciprocity-breaking is associated with specific ranges of excitation amplitudes for both impulse and harmonic forcing.", "doi": "10.1115/DETC2017-67965", "isbn": "978-0-7918-5822-6", "publisher": "American Society of Mechanical Engineers", "place_of_publication": "New York, NY", "publication_date": "2017-08", "pages": "Art. No. V008T12A023" }, { "id": "authors:y3vsx-7fc41", "collection": "authors", "collection_id": "y3vsx-7fc41", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170503-134705412", "type": "article", "title": "Intrinsically Polar Elastic Metamaterials", "author": [ { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-O-R" }, { "family_name": "S\u00fcsstrunk", "given_name": "Roman", "clpid": "S\u00fcsstrunk-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Huber", "given_name": "Sebastian D.", "orcid": "0000-0003-3558-351X", "clpid": "Huber-S-D" } ], "abstract": "In many applications, one needs to combine materials with varying properties to achieve certain functionalities. For example, the inner layer of a helmet should be soft for cushioning while the outer shell should be rigid to provide protection. Over time, these combined materials either separate or wear and tear, risking the exposure of an undesired material property. This work presents a design principle for a material that gains unique properties from its 3D microstructure, consisting of repeating basic building blocks, rather than its material composition. The 3D printed specimens show, at two of its opposing faces along the same axis, different stiffness (i.e., soft on one face and hard on the other). The realized material is protected by design (i.e., topology) against cuts and tears: No matter how material is removed, either layer by layer, or in arbitrary cuts through the repeating building blocks, two opposing faces remain largely different in their mechanical response.", "doi": "10.1002/adma.201700540", "issn": "0935-9648", "publisher": "Wiley", "publication": "Advanced Materials", "publication_date": "2017-07-12", "series_number": "26", "volume": "29", "issue": "26", "pages": "Art. No. 1700540" }, { "id": "authors:awrqf-j3t55", "collection": "authors", "collection_id": "awrqf-j3t55", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170403-135058832", "type": "article", "title": "Impact absorption properties of carbon fiber reinforced bucky sponges", "author": [ { "family_name": "Thevamaran", "given_name": "Ramathasan", "orcid": "0000-0001-5058-6167", "clpid": "Thevamaran-R" }, { "family_name": "Saini", "given_name": "Deepika", "clpid": "Saini-D" }, { "family_name": "Karakaya", "given_name": "Mehmet", "orcid": "0000-0002-4475-4352", "clpid": "Karakaya-M" }, { "family_name": "Zhu", "given_name": "Jingyi", "orcid": "0000-0001-7617-0557", "clpid": "Zhu-Jingyi" }, { "family_name": "Podila", "given_name": "Ramakrishna", "orcid": "0000-0003-0472-2361", "clpid": "Podila-R" }, { "family_name": "Rao", "given_name": "Apparao", "clpid": "Rao-A-M" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We describe the super compressible and highly recoverable response of bucky sponges as they are struck by a heavy flat-punch striker. The bucky sponges studied here are structurally stable, self-assembled mixtures of multiwalled carbon nanotubes (MWCNTs) and carbon fibers (CFs). We engineered the microstructure of the sponges by controlling their porosity using different CF contents. Their mechanical properties and energy dissipation characteristics during impact loading are presented as a function of their composition. The inclusion of CFs improves the impact force damping by up to 50% and the specific damping capacity by up to 7% compared to bucky sponges without CFs. The sponges also exhibit significantly better stress mitigation characteristics compared to vertically aligned carbon nanotube foams of similar densities. We show that delamination on the MWCNT-CF interfaces occurs during unloading, and arises from the heterogeneous fibrous microstructure of the bucky sponges.", "doi": "10.1088/1361-6528/aa6904", "issn": "0957-4484", "publisher": "IOP", "publication": "Nanotechnology", "publication_date": "2017-05-05", "series_number": "18", "volume": "28", "issue": "18", "pages": "Art. No. 184002" }, { "id": "authors:r4kzp-74b75", "collection": "authors", "collection_id": "r4kzp-74b75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170419-081903899", "type": "article", "title": "Bistable metamaterial for switching and cascading elastic vibrations", "author": [ { "family_name": "Bilal", "given_name": "Osama R.", "orcid": "0000-0003-3803-5084", "clpid": "Bilal-Osama-R" }, { "family_name": "Foehr", "given_name": "Andr\u00e9", "orcid": "0000-0003-0941-5424", "clpid": "Foehr-Andr\u00e9" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The realization of acoustic devices analogous to electronic systems, like diodes, transistors, and logic elements, suggests the potential use of elastic vibrations (i.e., phonons) in information processing, for example, in advanced computational systems, smart actuators, and programmable materials. Previous experimental realizations of acoustic diodes and mechanical switches have used nonlinearities to break transmission symmetry. However, existing solutions require operation at different frequencies or involve signal conversion in the electronic or optical domains. Here, we show an experimental realization of a phononic transistor-like device using geometric nonlinearities to switch and amplify elastic vibrations, via magnetic coupling, operating at a single frequency. By cascading this device in a tunable mechanical circuit board, we realize the complete set of mechanical logic elements and interconnect selected ones to execute simple calculations.", "doi": "10.1073/pnas.1618314114", "pmcid": "PMC5422829", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2017-05-02", "series_number": "18", "volume": "114", "issue": "18", "pages": "4603-4606" }, { "id": "authors:rmm7t-jst55", "collection": "authors", "collection_id": "rmm7t-jst55", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170410-124125950", "type": "article", "title": "Deployable micro-traps to sequester motile bacteria", "author": [ { "family_name": "Di Giacomo", "given_name": "Raffaele", "clpid": "Di-Giacomo-R" }, { "family_name": "Kr\u00f6del", "given_name": "Sebastian", "orcid": "0000-0002-9218-8578", "clpid": "Kr\u00f6del-S" }, { "family_name": "Maresca", "given_name": "Bruno", "clpid": "Maresca-B" }, { "family_name": "Benzoni", "given_name": "Patrizia", "clpid": "Benzoni-P" }, { "family_name": "Rusconi", "given_name": "Roberto", "clpid": "Rusconi-R" }, { "family_name": "Stocker", "given_name": "Roman", "clpid": "Stocker-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The development of strategies to reduce the load of unwanted bacteria is a fundamental challenge in industrial processing, environmental sciences and medical applications. Here, we report a new method to sequester motile bacteria from a liquid, based on passive, deployable micro-traps that confine bacteria using micro-funnels that open into trapping chambers. Even in low concentrations, micro-traps afford a 70% reduction in the amount of bacteria in a liquid sample, with a potential to reach >90% as shown by modelling improved geometries. This work introduces a new approach to contain the growth of bacteria without chemical means, an advantage of particular importance given the alarming growth of pan-drug-resistant bacteria.", "doi": "10.1038/srep45897", "pmcid": "PMC5381207", "issn": "2045-2322", "publisher": "Nature Publishing Group", "publication": "Scientific Reports", "publication_date": "2017-04-05", "volume": "7", "pages": "Art. No. 45897" }, { "id": "authors:g19zb-6et66", "collection": "authors", "collection_id": "g19zb-6et66", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170202-151758407", "type": "article", "title": "Biomimetic temperature-sensing layer for artificial skins", "author": [ { "family_name": "Di Giacomo", "given_name": "Raffaele", "clpid": "Di-Giacomo-R" }, { "family_name": "Bonanomi", "given_name": "Luca", "clpid": "Bonanomi-L" }, { "family_name": "Costanza", "given_name": "Vincenzo", "orcid": "0000-0002-2409-0632", "clpid": "Costanza-V" }, { "family_name": "Maresca", "given_name": "Bruno", "clpid": "Maresca-B" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Artificial membranes that are sensitive to temperature are needed in robotics to augment interactions with humans and the environment and in bioengineering to improve prosthetic limbs. Existing flexible sensors achieved sensitivities of <100 millikelvin and large responsivity, albeit within narrow (<5 kelvin) temperature ranges. Other flexible devices, working in wider temperature ranges, exhibit orders of magnitude poorer responses. However, much more versatile and temperature-sensitive membranes are present in animals such as pit vipers, whose pit membranes have the highest sensitivity and responsivity in nature and are used to locate warm-blooded prey at distance. We show that pectin films mimic the sensing mechanism of pit membranes and parallel their record performances. These films map temperature on surfaces with a sensitivity of at least 10 millikelvin in a wide temperature range (45 kelvin), have very high responsivity, and detect warm bodies at distance. The produced material can be integrated as a layer in artificial skin platforms and boost their temperature sensitivity to reach the best biological performance.", "doi": "10.1126/scirobotics.aai9251", "issn": "2470-9476", "publisher": "American Association for the Advancement of Science", "publication": "Science Robotics", "publication_date": "2017-03", "series_number": "3", "volume": "2", "issue": "3", "pages": "Art. No. eaai9251" }, { "id": "authors:b7mcp-cej40", "collection": "authors", "collection_id": "b7mcp-cej40", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170103-135347924", "type": "article", "title": "Engineered metabarrier as shield from seismic surface waves", "author": [ { "family_name": "Palermo", "given_name": "Antonio", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-Antonio" }, { "family_name": "Kr\u00f6del", "given_name": "Sebastian", "orcid": "0000-0002-9218-8578", "clpid": "Kr\u00f6del-Sebastian" }, { "family_name": "Marzani", "given_name": "Alessandro", "clpid": "Marzani-Alessandro" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Resonant metamaterials have been proposed to reflect or redirect elastic waves at different length scales, ranging from thermal vibrations to seismic excitation. However, for seismic excitation, where energy is mostly carried by surface waves, energy reflection and redirection might lead to harming surrounding regions. Here, we propose a seismic metabarrier able to convert seismic Rayleigh waves into shear bulk waves that propagate away from the soil surface. The metabarrier is realized by burying sub-wavelength resonant structures under the soil surface. Each resonant structure consists of a cylindrical mass suspended by elastomeric springs within a concrete case and can be tuned to the resonance frequency of interest. The design allows controlling seismic waves with wavelengths from 10-to-100\u2009m with meter-sized resonant structures. We develop an analytical model based on effective medium theory able to capture the mode conversion mechanism. The model is used to guide the design of metabarriers for varying soil conditions and validated using finite-element simulations. We investigate the shielding performance of a metabarrier in a scaled experimental model and demonstrate that surface ground motion can be reduced up to 50% in frequency regions below 10\u2009Hz, relevant for the protection of buildings and civil infrastructures.", "doi": "10.1038/srep39356", "pmcid": "PMC5172158", "issn": "2045-2322", "publisher": "Nature Publishing Group", "publication": "Scientific Reports", "publication_date": "2016-12-20", "volume": "6", "pages": "Art. No. 39356" }, { "id": "authors:v4c6w-bd397", "collection": "authors", "collection_id": "v4c6w-bd397", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170105-114706376", "type": "article", "title": "Microlattice Metamaterials for Tailoring Ultrasonic Transmission with Elastoacoustic Hybridization", "author": [ { "family_name": "Kr\u00f6del", "given_name": "Sebastian", "orcid": "0000-0002-9218-8578", "clpid": "Kr\u00f6del-S" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Materials with designed microscale architectures, like microlattices, can achieve extreme mechanical properties. Most studies of microlattices focus on their quasistatic response, but their structural dimensions naturally prime them for ultrasonic applications. Here we report that microlattices constitute a class of acoustic metamaterials that exploit elastoacoustic hybridization to tailor ultrasonic wave propagation. Selecting the microlattice geometry allows the formation of hybridization band gaps that effectively attenuate (by >2 orders of magnitude) acoustic signals. The hybridization gaps stem from the interaction of pressure waves in a surrounding medium (e.g., water) with localized bending modes of the trusses in the microlattice. Outside these band gaps, the microlattices are highly transmissive (>80%) because their acoustic impedance is close to that of water. Our work can have important implications in the design of acoustic metamaterial applications in biomedical imaging, cell-based assay technology, and acoustic isolators in microelectromechanical systems.", "doi": "10.1103/PhysRevApplied.6.064005", "issn": "2331-7019", "publisher": "American Physical Society", "publication": "Physical Review Applied", "publication_date": "2016-12", "series_number": "6", "volume": "6", "issue": "6", "pages": "Art. No. 064005" }, { "id": "authors:x39yx-zb610", "collection": "authors", "collection_id": "x39yx-zb610", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161128-121844703", "type": "article", "title": "Wave propagation in one-dimensional microscopic granular chains", "author": [ { "family_name": "Lin", "given_name": "Wei-Hsun", "clpid": "Lin-Wei-Hsun" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We employ noncontact optical techniques to generate and measure stress waves in uncompressed, one-dimensional microscopic granular chains, and support our experiments with discrete numerical simulations. We show that the wave propagation through dry particles (150 \u03bcm radius) is highly nonlinear and it is significantly influenced by the presence of defects (e.g., surface roughness, interparticle gaps, and misalignment). We derive an analytical relation between the group velocity and gap size, and define bounds for the formation of highly nonlinear solitary waves as a function of gap size and axial misalignment.", "doi": "10.1103/PhysRevE.94.052907", "issn": "2470-0045", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2016-11", "series_number": "5", "volume": "94", "issue": "5", "pages": "Art. No. 052907" }, { "id": "authors:tj534-f2818", "collection": "authors", "collection_id": "tj534-f2818", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160808-102406505", "type": "article", "title": "Stable propogation of mechanical signals in soft media using stored elastic energy", "author": [ { "family_name": "Raney", "given_name": "Jordan R.", "clpid": "Raney-J-R" }, { "family_name": "Nadkarni", "given_name": "Neel", "clpid": "Nadkarni-N" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Kochmann", "given_name": "Dennis M.", "orcid": "0000-0002-9112-6615", "clpid": "Kochmann-D-M" }, { "family_name": "Lewis", "given_name": "Jennifer A.", "clpid": "Lewis-J-A" }, { "family_name": "Bertoldi", "given_name": "Katia", "clpid": "Bertoldi-K" } ], "abstract": "Soft structures with rationally designed architectures capable of large, nonlinear deformation present opportunities for unprecedented, highly tunable devices and machines. However, the highly dissipative nature of soft materials intrinsically limits or prevents certain functions, such as the propagation of mechanical signals. Here we present an architected soft system composed of elastomeric bistable beam elements connected by elastomeric linear springs. The dissipative nature of the polymer readily damps linear waves, preventing propagation of any mechanical signal beyond a short distance, as expected. However, the unique architecture of the system enables propagation of stable, nonlinear solitary transition waves with constant, controllable velocity and pulse geometry over arbitrary distances. Because the high damping of the material removes all other linear, small-amplitude excitations, the desired pulse propagates with high fidelity and controllability. This phenomenon can be used to control signals, as demonstrated by the design of soft mechanical diodes and logic gates.", "doi": "10.1073/pnas.1604838113", "pmcid": "PMC5024640", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2016-08-30", "series_number": "35", "volume": "113", "issue": "35", "pages": "9722-9727" }, { "id": "authors:szer5-zhq74", "collection": "authors", "collection_id": "szer5-zhq74", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161007-080044914", "type": "article", "title": "Stable propagation of mechanical signals in soft media using stored elastic energy", "author": [ { "family_name": "Raney", "given_name": "Jordan R.", "clpid": "Raney-Jordan-R" }, { "family_name": "Nadkarni", "given_name": "Neel", "clpid": "Nadkarni-Neel" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Kochmann", "given_name": "Dennis M.", "orcid": "0000-0002-9112-6615", "clpid": "Kochmann-D-M" }, { "family_name": "Lewis", "given_name": "Jennifer A.", "clpid": "Lewis-Jennifer-A" }, { "family_name": "Bertoldi", "given_name": "Katia", "clpid": "Bertoldi-Katia" } ], "abstract": "Soft structures with rationally designed architectures capable of large, nonlinear deformation present opportunities for unprecedented, highly tunable devices and machines. However, the highly dissipative nature of soft materials intrinsically limits or prevents certain functions, such as the propagation of mechanical signals. Here we present an architected soft system composed of elastomeric bistable beam elements connected by elastomeric linear springs. The dissipative nature of the polymer readily damps linear waves, preventing propagation of any mechanical signal beyond a short distance, as expected. However, the unique architecture of the system enables propagation of stable, nonlinear solitary transition waves with constant, controllable velocity and pulse geometry over arbitrary distances. Because the high damping of the material removes all other linear, small-amplitude excitations, the desired pulse propagates with high fidelity and controllability. This phenomenon can be used to control signals, as demonstrated by the design of soft mechanical diodes and logic gates.", "doi": "10.1073/pnas.1604838113", "pmcid": "PMC5024640", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2016-08-30", "series_number": "35", "volume": "113", "issue": "35", "pages": "9722-9727" }, { "id": "authors:amp74-cw731", "collection": "authors", "collection_id": "amp74-cw731", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160316-135044479", "type": "article", "title": "Composite 3D-printed metastructures for low-frequency and broadband vibration absorption", "author": [ { "family_name": "Matlack", "given_name": "Kathryn H.", "orcid": "0000-0001-7387-2414", "clpid": "Matlack-K-H" }, { "family_name": "Bauhofer", "given_name": "Anton", "clpid": "Bauhofer-A" }, { "family_name": "Kr\u00f6del", "given_name": "Sebastian", "orcid": "0000-0002-9218-8578", "clpid": "Kr\u00f6del-S" }, { "family_name": "Palermo", "given_name": "Antonio", "orcid": "0000-0001-9431-0461", "clpid": "Palermo-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Architected material used to control elastic wave propagation has thus far relied on two mechanisms for forming band gaps, or frequency ranges that cannot propagate: (i) Phononic crystals rely on their structural periodicity to form Bragg band gaps, but are limited in the low-frequency ranges because their unit cell size scales with wavelength; and (ii) Metamaterials overcome this size dependence because they rely on local resonances, but the resulting band gaps are very narrow. Here, we introduce a class of materials, elastic metastructures, that exploit resonating elements to broaden and lower Bragg gaps while reducing the mass of the system. This approach to band-gap engineering can be used for low-frequency vibration absorption and wave guiding across length scales.", "doi": "10.1073/pnas.1600171113", "pmcid": "PMC4968765", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2016-07-26", "series_number": "30", "volume": "113", "issue": "30", "pages": "8386-8390" }, { "id": "authors:7yfqa-j6n34", "collection": "authors", "collection_id": "7yfqa-j6n34", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160316-135726780", "type": "article", "title": "A mechanical autonomous stochastic heat engine", "author": [ { "family_name": "Serra-Garcia", "given_name": "Marc", "clpid": "Serra-Garcia-M" }, { "family_name": "Foehr", "given_name": "Andr\u00e9", "orcid": "0000-0003-0941-5424", "clpid": "Foehr-A" }, { "family_name": "Moleron", "given_name": "Miguel", "clpid": "Moler\u00f3n-M" }, { "family_name": "Lydon", "given_name": "Joseph", "clpid": "Lydon-J" }, { "family_name": "Chong", "given_name": "Christopher", "clpid": "Chong-Christopher" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Stochastic heat engines are devices that generate work from random thermal motion using a small number of highly fluctuating degrees of freedom. Proposals for such devices have existed for more than a century and include the Maxwell demon and the Feynman ratchet. Only recently have they been demonstrated experimentally, using e.g., thermal cycles implemented in optical traps. However, the recent demonstrations of stochastic heat engines are nonautonomous, since they require an external control system that prescribes a heating and cooling cycle, and consume more energy than they produce. This Report presents a heat engine consisting of three coupled mechanical resonators (two ribbons and a cantilever) subject to a stochastic drive. The engine uses geometric nonlinearities in the resonating ribbons to autonomously convert a random excitation into a low-entropy, nonpassive oscillation of the cantilever. The engine presents the anomalous heat transport property of negative thermal conductivity, consisting in the ability to passively transfer energy from a cold reservoir to a hot reservoir.", "doi": "10.1103/PhysRevLett.117.010602", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2016-06-28", "series_number": "1", "volume": "117", "issue": "1", "pages": "Art. No. 010602" }, { "id": "authors:bjhwj-pky76", "collection": "authors", "collection_id": "bjhwj-pky76", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160613-102147574", "type": "article", "title": "Unidirectional Transition Waves in Bistable Lattices", "author": [ { "family_name": "Nadkarni", "given_name": "Neel", "clpid": "Nadkarni-N" }, { "family_name": "Arrieta", "given_name": "Andres F.", "clpid": "Arrieta-A-F" }, { "family_name": "Chong", "given_name": "Christopher", "clpid": "Chong-Christopher" }, { "family_name": "Kochmann", "given_name": "Dennis M.", "orcid": "0000-0002-9112-6615", "clpid": "Kochmann-D-M" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We present a model system for strongly nonlinear transition waves generated in a periodic lattice of bistable members connected by magnetic links. The asymmetry of the on-site energy wells created by the bistable members produces a mechanical diode that supports only unidirectional transition wave propagation with constant wave velocity. We theoretically justify the cause of the unidirectionality of the transition wave and confirm these predictions by experiments and simulations. We further identify how the wave velocity and profile are uniquely linked to the double-well energy landscape, which serves as a blueprint for transition wave control.", "doi": "10.1103/PhysRevLett.116.244501", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2016-06-17", "series_number": "24", "volume": "116", "issue": "24", "pages": "Art. No. 244501" }, { "id": "authors:9hc9k-29885", "collection": "authors", "collection_id": "9hc9k-29885", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160216-091322692", "type": "article", "title": "Rate-sensitive strain localization and impact response of carbon nanotube foams with microscale heterogeneous bands", "author": [ { "family_name": "Thevamaran", "given_name": "Ramathasan", "orcid": "0000-0001-5058-6167", "clpid": "Thevamaran-R" }, { "family_name": "Raney", "given_name": "Jordan R.", "clpid": "Raney-J-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We describe the deformation mechanisms and the bulk dynamic response of vertically aligned carbon nanotube (VACNT) foams comprised of bands of different densities. The densities of the bands are controlled during synthesis by varying the flow-rate of gas feedstock in discrete steps. We show that the impact response of VACNT foams can be distinctively tailored by introducing heterogeneous bands. For example, we demonstrate that this approach can be used to maintain the stress plateau at low stresses over a broad range of strains and to disrupt the expected progressive deformation of the sample. These are desirable characteristics for impact and energy absorption applications. The banded VACNT foams exhibit different deformation mechanisms in dynamics compared to those in quasistatic compression, as observed through in-situ high-speed microscopy.", "doi": "10.1016/j.carbon.2015.12.069", "issn": "0008-6223", "publisher": "Elsevier", "publication": "Carbon", "publication_date": "2016-05", "volume": "101", "pages": "184-190" }, { "id": "authors:xsdav-v0897", "collection": "authors", "collection_id": "xsdav-v0897", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160525-105808196", "type": "article", "title": "Nonlinear vibrational-state excitation and piezoelectric energy conversion in harmonically driven granular chains", "author": [ { "family_name": "Chong", "given_name": "C.", "clpid": "Chong-Christopher" }, { "family_name": "Kim", "given_name": "E.", "clpid": "Kim-E" }, { "family_name": "Charalampidis", "given_name": "E. G.", "clpid": "Charalampidis-E-G" }, { "family_name": "Kim", "given_name": "H.", "clpid": "Kim-H" }, { "family_name": "Li", "given_name": "F.", "clpid": "Li-Feng" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Lydon", "given_name": "J.", "clpid": "Lydon-J" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Yang", "given_name": "J.", "clpid": "Yang-Jinkyu" } ], "abstract": "This article explores the excitation of different vibrational states in a spatially extended dynamical system through theory and experiment. As a prototypical example, we consider a one-dimensional packing of spherical particles (a so-called granular chain) that is subject to harmonic boundary excitation. The combination of the multimodal nature of the system and the strong coupling between the particles due to the nonlinear Hertzian contact force leads to broad regions in frequency where different vibrational states are possible. In certain parametric regions, we demonstrate that the nonlinear Schr\u00f6dinger equation predicts the corresponding modes fairly well. The electromechanical model we apply predicts accurately the conversion from the obtained mechanical energy to the electrical energy observed in experiments.", "doi": "10.1103/PhysRevE.93.052203", "issn": "2470-0045", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2016-05", "series_number": "5", "volume": "93", "issue": "5", "pages": "Art. No. 052203" }, { "id": "authors:zsnv4-3rd38", "collection": "authors", "collection_id": "zsnv4-3rd38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160425-135937974", "type": "article", "title": "Universal energy transport law for dissipative and diffusive phase transitions", "author": [ { "family_name": "Nadkarni", "given_name": "Neel", "clpid": "Nadkarni-N" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Abeyaratne", "given_name": "Rohan", "clpid": "Abeyaratne-R" }, { "family_name": "Kochmann", "given_name": "Dennis M.", "orcid": "0000-0002-9112-6615", "clpid": "Kochmann-D-M" } ], "abstract": "We present a scaling law for the energy and speed of transition waves in dissipative and diffusive media. By considering uniform discrete lattices and continuous solids, we show that\u2014for arbitrary highly nonlinear many-body interactions and multistable on-site potentials\u2014the kinetic energy per density transported by a planar transition wave front always exhibits linear scaling with wave speed and the ratio of energy difference to interface mobility between the two phases. We confirm that the resulting linear superposition applies to highly nonlinear examples from particle to continuum mechanics.", "doi": "10.1103/PhysRevB.93.104109", "issn": "2469-9950", "publisher": "American Physical Society", "publication": "Physical Review B", "publication_date": "2016-03", "series_number": "10", "volume": "93", "issue": "10", "pages": "Art. No. 104109" }, { "id": "authors:43kh6-ztq44", "collection": "authors", "collection_id": "43kh6-ztq44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160316-134602220", "type": "article", "title": "Visco-thermal effects in acoustic metamaterials: from total transmission to total reflection and high absorption", "author": [ { "family_name": "Moler\u00f3n", "given_name": "Miguel", "clpid": "Moler\u00f3n-M" }, { "family_name": "Serra-Garcia", "given_name": "Marc", "clpid": "Serra-Garcia-M" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We theoretically and experimentally investigate visco\u2013thermal effects on the acoustic propagation through metamaterials consisting of rigid slabs with subwavelength slits embedded in air. We demonstrate that this unavoidable loss mechanism is not merely a refinement, but that it plays a dominant role in the actual acoustic response of the structure. Specifically, in the case of very narrow slits, the visco\u2013thermal losses avoid completely the excitation of Fabry\u2013Perot resonances, leading to 100% reflection. This is exactly opposite to the perfect transmission predicted in the idealised lossless case. Moreover, for a wide range of geometrical parameters, there exists an optimum slit width at which the energy dissipated in the structure can be as high as 50%. This work provides a clear evidence that visco\u2013thermal effects are necessary to describe realistically the acoustic response of locally resonant metamaterials.", "doi": "10.1088/1367-2630/18/3/033003", "issn": "1367-2630", "publisher": "IOP", "publication": "New Journal of Physics", "publication_date": "2016-03", "series_number": "3", "volume": "18", "issue": "3", "pages": "Art. No. 033003" }, { "id": "authors:62wsk-3pe45", "collection": "authors", "collection_id": "62wsk-3pe45", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160204-151714588", "type": "article", "title": "Extreme stiffness tunability through the excitation of nonlinear defect modes", "author": [ { "family_name": "Serra-Garcia", "given_name": "M.", "clpid": "Serra-Garcia-M" }, { "family_name": "Lydon", "given_name": "J.", "clpid": "Lydon-J" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The incremental stiffness characterizes the variation of a material's force response to a small deformation change. In lattices with noninteracting vibrational modes, the excitation of localized states does not have any effect on material properties, such as the incremental stiffness. We report that, in nonlinear lattices, driving a defect mode introduces changes in the static force-displacement relation of the material. By varying the defect excitation frequency and amplitude, the incremental stiffness can be tuned continuously to arbitrarily large positive or negative values. Furthermore, the defect excitation parameters also determine the displacement region at which the force-displacement relation is being tuned. We demonstrate this phenomenon experimentally in a compressed array of spheres tuning its incremental stiffness from a finite positive value to zero and continuously down to negative infinity.", "doi": "10.1103/PhysRevE.93.010901", "issn": "2470-0045", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2016-01-12", "series_number": "1", "volume": "93", "issue": "1", "pages": "Art. No. 010901(R)" }, { "id": "authors:w04cf-yk485", "collection": "authors", "collection_id": "w04cf-yk485", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160930-134530953", "type": "article", "title": "Mechanical properties of parts fabricated with inkjet 3D printing through efficient experimental design", "author": [ { "family_name": "Mueller", "given_name": "J.", "orcid": "0000-0002-4808-2223", "clpid": "Mueller-Jochen" }, { "family_name": "Shea", "given_name": "K.", "clpid": "Shea-K" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "To design and optimize parts for additive manufacturing (AM) processes it is necessary to understand their variations in geometric and mechanical properties. In this work, such variations of inkjet 3D printed structures are systematically investigated by analyzing parameters of the whole process. The aim is to determine and quantify the parameters that lead to the most accurate geometry and to the best mechanical properties. Using this understanding, it is possible to build accurate part models and optimize, fabricate and test them successfully. Significant impacts on the mechanical properties are found, in descending order, for the number of intersections between layers and nozzles orthogonal to the load-direction, the exposure time to ultraviolet light, the position on the printing table and the expiry date of the raw material. Nozzle blockage significantly affects the geometry and also the machine's warm-up time is an important factor. Minor effects are found for the storage time and the surface roughness is not affected by any factor. Since AM materials change rapidly and the characterization process will have to be repeated, it is shown how to fully exploit the Design of Experiments method to create a cost and time efficient design with a high statistical accuracy.", "doi": "10.1016/j.matdes.2015.07.129", "issn": "0261-3069", "publisher": "Elsevier", "publication": "Materials and Design", "publication_date": "2015-12-05", "volume": "86", "pages": "902-912" }, { "id": "authors:2c626-bt454", "collection": "authors", "collection_id": "2c626-bt454", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160316-135431197", "type": "monograph", "title": "Artificial membranes biomimicking pit vipers' thermal sensing", "author": [ { "family_name": "Di Giacomo", "given_name": "Raffaele", "clpid": "Di-Giacomo-R" }, { "family_name": "Bonanomi", "given_name": "Luca", "clpid": "Bonanomi-L" }, { "family_name": "Costanza", "given_name": "Vincenzo", "orcid": "0000-0002-2409-0632", "clpid": "Costanza-V" }, { "family_name": "Maresca", "given_name": "Bruno", "clpid": "Maresca-B" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Artificial membranes that are sensitive to temperature are needed in robotics to augment interactions with humans and the environment, and in bioengineering to improve prosthetic limbs. Existing flexible sensors achieved sensitivities of <100 mK, albeit within narrow (<5 K) temperature ranges. Other flexible devices, working in wider temperature ranges, exhibit orders of magnitude poorer responses. However, much more versatile and temperature sensitive membranes are found in animals such as pit vipers, whose pit membranes have the highest sensitivity in nature and are used to locate warm-blooded preys at distance. Here, we show that pectin films mimic the sensing mechanism of pit membranes and parallel their record performance. These films map temperature on surfaces with a sensitivity of <10 mK in a wide temperature range (40 K) and detect warm bodies at distance.", "doi": "10.48550/arXiv.1512.01161", "publication_date": "2015-12-03" }, { "id": "authors:4c4k7-n9k17", "collection": "authors", "collection_id": "4c4k7-n9k17", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-133155152", "type": "article", "title": "Solitary wave-based delamination detection in composite plates using a combined granular crystal sensor and actuator", "author": [ { "family_name": "Kim", "given_name": "Eunho", "clpid": "Kim-Eunho" }, { "family_name": "Restuccia", "given_name": "Francesco", "clpid": "Restuccia-F" }, { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We experimentally and numerically investigate a diagnostic method for detecting hidden delamination in composite panels, using highly nonlinear solitary waves. Solitary waves are a type of nonlinear waves with strong energy intensity and non-distortive nature, which can be controllably generated in one-dimensional granular crystals. In this study, we use granular crystals as a combined sensor and actuator to detect hidden delamination in carbon fiber reinforced polymer (CFRP) composite panels. Specifically, we locally excite a CFRP composite specimen using the granular crystal as an actuator and measure the reflected waves that carry the specimen's diagnostic information using the same device as a sensor. We first investigate the effect of the panel's boundary conditions on the response of the reflected solitary waves. We then investigate the interactions of a solitary wave with delamination hidden in the CFRP composite specimen. Lastly, we define a damage index based on the solitary waves' responses to identify the location of the hidden delamination in the CFRP composite panel. The solitary wave-based diagnostic method can provide unique merits, such as portable and fast sensing of composites' hidden damage, thereby with the potential of being used for hot spot monitoring of composite-based structures.", "doi": "10.1088/0964-1726/24/12/125004", "issn": "0964-1726", "publisher": "IoP Publishing", "publication": "Smart Materials and Structures", "publication_date": "2015-12", "series_number": "12", "volume": "24", "issue": "12", "pages": "Art. No. 125004" }, { "id": "authors:qs54t-1bp12", "collection": "authors", "collection_id": "qs54t-1bp12", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160930-150900119", "type": "article", "title": "Granular crystals: Nonlinear dynamics meets materials engineering", "author": [ { "family_name": "Porter", "given_name": "Mason A.", "clpid": "Porter-M-A" }, { "family_name": "Kevrekidis", "given_name": "Panayotis G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The freedom to choose the size, stiffness, and spatial distribution of macroscopic particles in a lattice makes granular crystals easily tailored building blocks for shock-absorbing materials, sound-focusing devices, acoustic switches, and other exotica.", "doi": "10.1063/PT.3.2981", "issn": "0031-9228", "publisher": "American Institute of Physics", "publication": "Physics Today", "publication_date": "2015-11", "series_number": "11", "volume": "68", "issue": "11", "pages": "44-50" }, { "id": "authors:y350t-z1f69", "collection": "authors", "collection_id": "y350t-z1f69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151012-134855612", "type": "article", "title": "Dynamic Behavior of Vertically Aligned Carbon Nanotube Foams With Patterned Microstructure", "author": [ { "family_name": "Lattanzi", "given_name": "Ludovica", "clpid": "Lattanza-L" }, { "family_name": "Thevamaran", "given_name": "Ramathasan", "orcid": "0000-0001-5058-6167", "clpid": "Thevamaran-R" }, { "family_name": "De Nardo", "given_name": "Luigi", "orcid": "0000-0002-7492-6012", "clpid": "De-Nardo-L" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We present the design, fabrication, and dynamic characterization of micropatterned vertically aligned carbon nanotube (VACNT) foams. The foams' synthesis combines photolithographic techniques with chemical vapor deposition to create materials with an effective density up to five times lower than that of bulk VACNT foams. The dynamic response of these lightweight materials is characterized by performing impact tests at different strain rates. Results show that the dynamic stress\u2013strain behavior of the micropatterned foams is governed by the patterns' geometry and has negligible dependence on their bulk density. The energy absorption of the micropatterned foams is higher than most other energy absorbing materials, such as honeycombs, foams, and composites of comparable density. Highly organized CNT microstructures can be employed as lightweight material for protective applications.", "doi": "10.1002/adem.201400571", "issn": "1438-1656", "publisher": "Wiley Verlag", "publication": "Advanced Engineering Materials", "publication_date": "2015-10", "series_number": "10", "volume": "17", "issue": "10", "pages": "1470-1479" }, { "id": "authors:9ntw2-eay93", "collection": "authors", "collection_id": "9ntw2-eay93", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160930-160503875", "type": "article", "title": "Wide band-gap seismic metastructures", "author": [ { "family_name": "Kr\u00f6del", "given_name": "S.", "orcid": "0000-0002-9218-8578", "clpid": "Kr\u00f6del-S" }, { "family_name": "Thom\u00e9", "given_name": "N.", "clpid": "Thom\u00e9-N" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Metamaterials exploit local resonances to reflect acoustic signals with wavelengths well above the characteristic size of the material's structure. This has allowed obtaining materials that present low-frequency (albeit narrow) band gaps or devices for optical and acoustic cloaking. In this work, we propose to use an array of resonating structures (herein termed a \"metastructure\") buried around sensitive buildings to control the propagation of seismic waves. These seismic metastructures consist of arrays of cylindrical tubes containing a resonator suspended by soft bearings. To obtain broadband attenuation characteristics, each resonator in the array is designed to exhibit a different eigenfrequency. We study the response of these systems using numerical analysis and scaled (1:30) experiments. We target wave mitigation in the infrasound regime (1\u201310 Hz), a range of frequencies relevant for the protection of large buildings.", "doi": "10.1016/j.eml.2015.05.004", "issn": "2352-4316", "publisher": "Elsevier", "publication": "Extreme Mechanics Letters", "publication_date": "2015-09", "volume": "4", "pages": "111-117" }, { "id": "authors:zr0dm-p0d62", "collection": "authors", "collection_id": "zr0dm-p0d62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150716-121038862", "type": "article", "title": "Elastic-Plastic Wave Propagation in Uniform and Periodic Granular Chains", "author": [ { "family_name": "Burgoyne", "given_name": "Hayden A.", "clpid": "Burgoyne-H-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate the properties of high-amplitude stress waves propagating through chains of elastic\u2013plastic particles using experiments and simulations. We model the system after impact using discrete element method (DEM) with strain-rate dependent contact interactions. Experiments are performed on a Hopkinson bar coupled with a laser vibrometer. The bar excites chains of 50 identical particles and dimer chains of two alternating materials. After investigating how the speed of the initial stress wave varies with particle properties and loading amplitude, we provide an upper bound for the leading pulse velocity that can be used to design materials with tailored wave propagation.", "doi": "10.1115/1.4030458", "issn": "0021-8936", "publisher": "American Society Mechanical Engineers", "publication": "Journal of Applied Mechanics", "publication_date": "2015-08", "series_number": "8", "volume": "82", "issue": "8", "pages": "Art. No. 081002" }, { "id": "authors:nt2jf-jf373", "collection": "authors", "collection_id": "nt2jf-jf373", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160812-075217608", "type": "book_section", "title": "Tensile Properties of Inkjet 3D Printed Parts: Critical Process Parameters and Their Efficient Analysis", "book_title": "35th Computers and Information in Engineering Conference", "author": [ { "family_name": "Mueller", "given_name": "Jochen", "orcid": "0000-0002-4808-2223", "clpid": "Mueller-Jochen" }, { "family_name": "Kim", "given_name": "Shi En", "clpid": "Kim-Shi-En" }, { "family_name": "Shea", "given_name": "Kristina", "orcid": "0000-0003-3921-2214", "clpid": "Shea-Kristina" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "To design and optimize for capabilities of additive manufacturing processes it is also necessary to understand and model their variations in geometric and mechanical properties. In this paper, such variations of inkjet 3D printed parts are systematically investigated by analyzing parameters of the whole process, i.e. storage of the material, printing, testing, and storage of finished parts. The goal is to both understand the process and determine the parameters that lead to the best mechanical properties and the most accurate geometric properties. Using models based on this understanding, we can design and optimize parts, and fabricate and test them successfully, thus closing the loop. Since AM materials change rapidly and this process will have to be repeated, it is shown how to create a cost and time efficient experimental design with the one-factor-at-a-time and design of experiments methods, yielding high statistical accuracies for both main and interaction effects. The results show that the number of intersections between layers and nozzles along the load-direction has the strongest impact on the mechanical properties followed by the UV exposure time, which is investigated by part spacing, the position on the printing table and the expiry date of the material. Minor effects are found for the storage time and the surface roughness is not affected by any factor. Nozzle blockage, which leads to a smaller flow-rate of printing material, significantly affected the width and waviness of the printed product. Furthermore, the machine's warm-up time is found to be an important factor.", "doi": "10.1115/DETC2015-48024", "isbn": "978-0-7918-5704-5", "publisher": "American Society of Mechanical Engineers", "place_of_publication": "New York, NY", "publication_date": "2015-08", "pages": "Art. No. V01AT02A040" }, { "id": "authors:zc2xy-2cs74", "collection": "authors", "collection_id": "zc2xy-2cs74", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150918-145337055", "type": "article", "title": "Acoustic metamaterial for subwavelength edge detection", "author": [ { "family_name": "Moler\u00f3n", "given_name": "Miguel", "clpid": "Moler\u00f3n-Miguel" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Metamaterials have demonstrated the possibility to produce super-resolved images by\nrestoring propagative and evanescent waves. However, for efficient information transfer,\nfor example, in compressed sensing, it is often desirable to visualize only the fast spatial\nvariations of the wave field (carried by evanescent waves), as the one created by edges or\nsmall details. Image processing edge detection algorithms perform such operation, but they\nadd time and complexity to the imaging process. Here we present an acoustic metamaterial\nthat transmits only components of the acoustic field that are approximately equal to or\nsmaller than the operating wavelength. The metamaterial converts evanescent waves into\npropagative waves exciting trapped resonances, and it uses periodicity to attenuate the\npropagative components. This approach achieves resolutions ~5 times smaller than the\noperating wavelength and makes it possible to visualize independently edges aligned along\ndifferent directions.", "doi": "10.1038/ncomms9037", "pmcid": "PMC4560791", "issn": "2041-1723", "publisher": "Nature Publishing Group", "publication": "Nature Communications", "publication_date": "2015-08", "series_number": "8", "volume": "6", "issue": "8", "pages": "Art. No. 8037" }, { "id": "authors:q8d1p-nys97", "collection": "authors", "collection_id": "q8d1p-nys97", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160930-151255742", "type": "article", "title": "Microstructures to control elasticity in 3D printing", "author": [ { "family_name": "Schumacher", "given_name": "Christian", "clpid": "Schumacher-C" }, { "family_name": "Bickel", "given_name": "Bernd", "orcid": "0000-0001-6511-9385", "clpid": "Bickel-B" }, { "family_name": "Rys", "given_name": "Jan", "clpid": "Rys-J" }, { "family_name": "Marschner", "given_name": "Steve", "clpid": "Marschner-S" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Gross", "given_name": "Markus", "clpid": "Gross-M" } ], "abstract": "We propose a method for fabricating deformable objects with spatially varying elasticity using 3D printing. Using a single, relatively stiff printer material, our method designs an assembly of small-scale microstructures that have the effect of a softer material at the object scale, with properties depending on the microstructure used in each part of the object. We build on work in the area of metamaterials, using numerical optimization to design tiled microstructures with desired properties, but with the key difference that our method designs families of related structures that can be interpolated to smoothly vary the material properties over a wide range. To create an object with spatially varying elastic properties, we tile the object's interior with microstructures drawn from these families, generating a different microstructure for each cell using an efficient algorithm to select compatible structures for neighboring cells. We show results computed for both 2D and 3D objects, validating several 2D and 3D printed structures using standard material tests as well as demonstrating various example applications.", "doi": "10.1145/2766926", "issn": "0730-0301", "publisher": "Association for Computing Machinery", "publication": "ACM Transactions on Graphics", "publication_date": "2015-08", "series_number": "4", "volume": "34", "issue": "4", "pages": "Art. No. 136" }, { "id": "authors:qfzjp-8gg64", "collection": "authors", "collection_id": "qfzjp-8gg64", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150807-074704258", "type": "article", "title": "Self-Assembled Recyclable Hierarchical Bucky Aerogels", "author": [ { "family_name": "Karakaya", "given_name": "Mehmet", "orcid": "0000-0002-4475-4352", "clpid": "Karakaya-M" }, { "family_name": "Saini", "given_name": "Deepika", "clpid": "Saini-D" }, { "family_name": "Podila", "given_name": "Ramakrishna", "orcid": "0000-0003-0472-2361", "clpid": "Podila-R" }, { "family_name": "Skove", "given_name": "Malcolm J.", "clpid": "Skove-M-J" }, { "family_name": "Rao", "given_name": "Apparao M.", "clpid": "Rao-A-M" }, { "family_name": "Thevamaran", "given_name": "Ramathasan", "orcid": "0000-0001-5058-6167", "clpid": "Thevamaran-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We describe a simple method for the scalable synthesis of three-dimensional, elastic, and recyclable multi-wall carbon nanotube (MWCNT) based light weight (density <1 g cm^(\u22123)) bucky-aerogels (BAGs) that are capable of efficiently absorbing non-polar solvents and separating oil-in-water emulsions. Our facile synthesis involves the self-assembly of MWCNTs and carbon fibers into a multi-layered, highly porous, and hierarchical structure that can be easily flexed, compressed, or burnt without any noticeable changes in its structure and absorption capacity. The BAG surface absorbs non-polar solvents efficiently up to \u224820 times its own weight due to its superhydrophobic nature arising from the presence of MWCNTs. Furthermore, BAGs exhibit excellent resilience to impact by recovering more than 70% of the deformation. The energy dissipated by BAGs at 80% compressive strain is in the order of 500 kJ m^(\u22123), which is nearly 50 times more than the energy dissipated by commercial foams with similar densities.", "doi": "10.1002/adem.201400414", "issn": "1438-1656", "publisher": "Wiley", "publication": "Advanced Engineering Materials", "publication_date": "2015-07", "series_number": "7", "volume": "17", "issue": "7", "pages": "990-994" }, { "id": "authors:wcjey-2ha03", "collection": "authors", "collection_id": "wcjey-2ha03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160825-100505056", "type": "article", "title": "Guided Impact Mitigation in 2D and 3D Granular Crystals", "author": [ { "family_name": "Burgoyne", "given_name": "Hayden A.", "clpid": "Burgoyne-H-A" }, { "family_name": "Newman", "given_name": "John A.", "orcid": "0000-0001-8684-2222", "clpid": "Newman-J-A" }, { "family_name": "Jackson", "given_name": "Wade C.", "clpid": "Jackson-W-C" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We simulate the dynamics of impacts on 1D, 2D and 3D arrays of metallic spheres in order to design novel granular protection systems. The dynamics of these highly organized systems of spheres, commonly called granular crystals, are governed by the contact law that describes how each particle interacts with the others. We use our recently developed force-displacement model of the dynamic compression of elastic-plastic spheres as the building block to investigate the response of systems comprised of metallic spheres to an impact. We first provide preliminary experimental results using a drop tower as validation of our numerical approach for 2D and 3D systems. We then use simulations of large periodic granular crystals in order to determine which particle properties govern the velocity of stress waves in these materials. We show that the properties of 1D systems can be scaled to predict the behavior of more complex 2D and 3D granular crystals. Because we can choose the material properties of each of the constituent particles and design how the particles are geometrically packed, we can leverage the heterogeneity of the system to create materials with unique properties such as anisotropic local stiffnesses and wave propagation velocities. We show that these materials allow us to design the dispersion and dissipation properties within the material in order to influence the propagation of a stress wave. Using these materials, we can therefore design protection systems or armor that directs damage away from sensitive parts or localizes damage to an unimportant area after impact from a projectile or a blast.", "doi": "10.1016/j.proeng.2015.04.008", "issn": "1877-7058", "publisher": "Elsevier", "publication": "Procedia Engineering", "publication_date": "2015-05-19", "volume": "103", "pages": "52-59" }, { "id": "authors:v49y3-twt81", "collection": "authors", "collection_id": "v49y3-twt81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141222-104530792", "type": "article", "title": "Shock formation and rate effects in impacted carbon nanotube foams", "author": [ { "family_name": "Thevamaran", "given_name": "Ramathasan", "orcid": "0000-0001-5058-6167", "clpid": "Thevamaran-R" }, { "family_name": "Meshot", "given_name": "Eric R.", "orcid": "0000-0002-7951-6696", "clpid": "Meshot-E-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate rate-effects in the dynamic response of vertically aligned carbon nanotube (VACNT) foams excited by impacts at controlled velocities. They exhibit a complex rate-dependent loading\u2013unloading response at low impact velocities and they support shock formation beyond a critical velocity. The measured critical velocities are \u223c10 times lower than in other foams of similar densities\u2014a desirable characteristic in impact protective applications. In-situ high-speed microscopy reveals strain localization and progressive buckling at low velocities and a crush-front propagation during shock compression. We correlate these responses to quantitative measurements of the density gradient and fiber morphology, obtained with spatially resolved X-ray scattering and mass attenuation.", "doi": "10.1016/j.carbon.2014.12.006", "issn": "0008-6223", "publisher": "Elsevier", "publication": "Carbon", "publication_date": "2015-04", "volume": "84", "pages": "390-398" }, { "id": "authors:e8xe4-tf365", "collection": "authors", "collection_id": "e8xe4-tf365", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150331-121144566", "type": "article", "title": "Plant nanobionic materials with a giant temperature response mediated by pectin-Ca\u207a\u00b2", "author": [ { "family_name": "Di Giacomo", "given_name": "Raffaele", "clpid": "Di-Giacomo-Raffaele" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Maresca", "given_name": "Bruno", "orcid": "0000-0001-7092-4995", "clpid": "Maresca-Bruno" } ], "abstract": "Conventional approaches to create biomaterials rely on reverse engineering of biological structures, on biomimicking, and on bioinspiration. Plant nanobionics is a recent approach to engineer new materials combining plant organelles with synthetic nanoparticles to enhance, for example, photosynthesis. Biological structures often outperform man-made materials. For example, higher plants sense temperature changes with high responsivity. However, these properties do not persist after cell death. Here, we permanently stabilize the temperature response of isolated plant cells adding carbon nanotubes (CNTs). Interconnecting cells, we create materials with an effective temperature coefficient of electrical resistance (TCR) of \u22121,730% K\u207b\u00b9, \u223c2 orders of magnitude higher than the best available sensors. This extreme temperature response is due to metal ions contained in the egg-box structure of the pectin backbone, lodged between cellulose microfibrils. The presence of a network of CNTs stabilizes the response of cells at high temperatures without decreasing the activation energy of the material. CNTs also increase the background conductivity, making these materials suitable elements for thermal and distance sensors.", "doi": "10.1073/pnas.1421020112", "pmcid": "PMC4403192", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2015-03-31", "series_number": "15", "volume": "112", "issue": "15", "pages": "4541-4545" }, { "id": "authors:94bpw-zaj92", "collection": "authors", "collection_id": "94bpw-zaj92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150501-132716425", "type": "article", "title": "Wave propagation in granular chains with local resonances", "author": [ { "family_name": "Bonanomi", "given_name": "Luca", "clpid": "Bonanomi-L" }, { "family_name": "Theocharis", "given_name": "Georgios", "clpid": "Theocharis-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study wave propagation in a chain of spherical particles containing a local resonator. The resonant particles are made of an aluminum outer spherical shell and a steel inner mass connected by a polymeric plastic structure acting as a spring. We characterize the dynamic response of individual particles and the transmitted linear spectra of a chain of particles in contact. A wide band gap is observed both in theoretical and experimental results. We show the ability to tune the acoustic transmission by varying the contact interaction between particles. Higher driving amplitude leads to the generation of nonlinearities both in the response of a single particle and that of the whole chain. For a single resonant particle, we observe experimentally a resonant frequency downshift, which follows a complex nonlinear behavior. In the chain of particles, nonlinearity leads to the generation of nonlinear harmonics and the presence of localized modes inside the band gap.", "doi": "10.1103/PhysRevE.91.033208", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2015-03", "series_number": "3", "volume": "91", "issue": "3", "pages": "Art. No. 033208" }, { "id": "authors:yrwdg-pdx43", "collection": "authors", "collection_id": "yrwdg-pdx43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150401-100212731", "type": "article", "title": "Anomalous impact and strain responses in helical carbon nanotube foams", "author": [ { "family_name": "Thevamaran", "given_name": "Ramathasan", "orcid": "0000-0001-5058-6167", "clpid": "Thevamaran-R" }, { "family_name": "Karakaya", "given_name": "Mehmet", "orcid": "0000-0002-4475-4352", "clpid": "Karakaya-M" }, { "family_name": "Meshot", "given_name": "Eric R.", "orcid": "0000-0002-7951-6696", "clpid": "Meshot-E-R" }, { "family_name": "Fischer", "given_name": "Andre", "clpid": "Fischer-A" }, { "family_name": "Podilla", "given_name": "Ramakrishna", "clpid": "Podilla-R" }, { "family_name": "Rao", "given_name": "Apparao M.", "clpid": "Rao-A-M" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We describe the quasistatic and dynamic response of helical carbon nanotube (HCNT) foams in compression. Similarly to other CNT foams, HCNT foams exhibit preconditioning effects in response to cyclic loading; however, their fundamental deformation mechanisms are unique. In quasistatic compression, HCNT foams exhibit strain localization and collective structural buckling, nucleating at different weak sections throughout their thickness. In dynamic compression, they undergo progressive crushing, governed by the intrinsic density gradient along the thickness of the sample. HCNT micro-bundles often undergo brittle fracture that originates from nanoscale defects. Regardless of this microstructural damage, bulk HCNT foams exhibit super-compressibility and recover more than 90% of large compressive strains (up to 80%). When subjected to striker impacts, HCNT foams mitigate impact stresses more effectively compared to other CNT foams comprised of non-helical CNTs ([similar]50% improvement). The unique mechanical properties we revealed demonstrate that the HCNT foams are ideally suited for applications in packaging, impact protection, and vibration mitigation.", "doi": "10.1039/C5RA03561A", "issn": "2046-2069", "publisher": "Royal Society of Chemistry", "publication": "RSC Advances", "publication_date": "2015-02-27", "series_number": "37", "volume": "5", "issue": "37", "pages": "29306-29311" }, { "id": "authors:gawmx-5c697", "collection": "authors", "collection_id": "gawmx-5c697", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150410-131513029", "type": "article", "title": "Nonlinear resonances and energy transfer in finite granular chains", "author": [ { "family_name": "Lydon", "given_name": "Joseph", "clpid": "Lydon-J" }, { "family_name": "Theocharis", "given_name": "Georgios", "clpid": "Theocharis-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In the present work we test experimentally and compute numerically the stability and dynamics of harmonically driven monoatomic granular chains composed of an increasing number of particles N(N=1-50). In particular, we investigate the inherent effects of dissipation and finite size on the evolution of bifurcation instabilities in the statically compressed case. The findings of the study suggest that the nonlinear bifurcation phenomena, which arise due to finite size, can be useful for efficient energy transfer away from the drive frequency in transmitted waves.", "doi": "10.1103/PhysRevE.91.023208", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2015-02", "series_number": "2", "volume": "91", "issue": "2", "pages": "Art. No. 023208" }, { "id": "authors:p4vd4-08677", "collection": "authors", "collection_id": "p4vd4-08677", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150129-085636801", "type": "article", "title": "Wave mitigation in ordered networks of granular chains", "author": [ { "family_name": "Leonard", "given_name": "Andrea", "clpid": "Leonard-Andrea-B" }, { "family_name": "Ponson", "given_name": "Laurent", "clpid": "Ponson-L" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the propagation of stress waves through ordered 2D networks of granular chains. The quasi-particle continuum theory employed captures the acoustic pulse splitting, bending, and recombination through the network and is used to derive its effective acoustic properties. The strong wave mitigation properties of the network predicted theoretically are confirmed through both numerical simulations and experimental tests. In particular, the leading pulse amplitude propagating through the system is shown to decay exponentially with the propagation distance and the spatial structure of the transmitted wave shows an exponential localization along the direction of the incident wave. The length scales that characterized these exponential decays are studied and determined as a function of the geometrical properties of the network. These results open avenues for the design of efficient impact mitigating structures and provide new insights into the mechanisms of wave propagation in granular matter.", "doi": "10.1016/j.jmps.2014.08.004", "issn": "0022-5096", "publisher": "Elsevier", "publication": "Journal of the Mechanics and Physics of Solids", "publication_date": "2014-12-15", "volume": "73", "pages": "103-117" }, { "id": "authors:969x5-nbj38", "collection": "authors", "collection_id": "969x5-nbj38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160930-154241744", "type": "article", "title": "Exponential stress mitigation in structured granular composites", "author": [ { "family_name": "Leonard", "given_name": "Andrea", "clpid": "Leonard-Andrea-B" }, { "family_name": "Ponson", "given_name": "Laurent", "clpid": "Ponson-L" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Granular media has been used throughout history as rudimentary yet effective impact mitigation. The unique response of natural granular media is associated with the existence of a network of stress propagation pathways, i.e. a force chain network, which spatially and temporally redirects and moderates the impulse. A variety of structured materials have been proposed to improve the impact mitigating properties compared to natural systems. However, these engineered materials use permanent deformation or viscoelastic properties to dissipate energy, generally limiting their lifetime or effective frequency and temperature range. Here, we take inspiration from natural granular media to engineer a structured composite that exhibits an exponentially fast decay of the leading transmitted pulses. The ordered network geometry allows for an analytical description of the transmitted pulses, which we validate though experiments and numerical simulations. In contrast to other structured materials used for impact mitigation, these networks exhibit reversible deformation, function over all frequencies, and possess a low relative density. Our results open new possibilities for the design and realization of increasingly complex material systems with engineered stress wave transmission pathways.", "doi": "10.1016/j.eml.2014.12.005", "issn": "2352-4316", "publisher": "Elsevier", "publication": "Extreme Mechanics Letters", "publication_date": "2014-12", "volume": "1", "pages": "23-28" }, { "id": "authors:ffbjt-r3z59", "collection": "authors", "collection_id": "ffbjt-r3z59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150309-112602998", "type": "article", "title": "Multiscale Mass-Spring Model for High-Rate Compression of Vertically Aligned Carbon Nanotube Foams", "author": [ { "family_name": "Thevamaran", "given_name": "Ramathasan", "orcid": "0000-0001-5058-6167", "clpid": "Thevamaran-R" }, { "family_name": "Fraternali", "given_name": "Fernando", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We present a one-dimensional, multiscale mass-spring model to describe the response of vertically aligned carbon nanotube (VACNT) foams subjected to uniaxial, high-rate compressive deformations. The model uses mesoscopic dissipative spring elements composed of a lower level chain of asymmetric, bilateral, bistable elastic springs to describe the experimentally observed deformation-dependent stress\u2013strain responses. The model shows an excellent agreement with the experimental response of VACNT foams undergoing finite deformations and enables in situ identification of the constitutive parameters at the smaller lengthscales. We apply the model to two cases of VACNT foams impacted at 1.75\u2009ms^(\u22121) and 4.44\u2009ms^(\u22121) and describe their dynamic response.", "doi": "10.1115/1.4028785", "issn": "0021-8936", "publisher": "American Society Mechanical Engineers", "publication": "Journal of Applied Mechanics", "publication_date": "2014-12", "series_number": "12", "volume": "81", "issue": "12", "pages": "Art. No. 121006" }, { "id": "authors:x4kmv-aeb38", "collection": "authors", "collection_id": "x4kmv-aeb38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141212-102628952", "type": "article", "title": "Wave transmission in time- and space-variant helicoidal phononic crystals", "author": [ { "family_name": "Li", "given_name": "F.", "clpid": "Li-Feng" }, { "family_name": "Chong", "given_name": "C.", "clpid": "Chong-C" }, { "family_name": "Yang", "given_name": "J.", "clpid": "Yang-Jinkyu" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We present a dynamically tunable mechanism of wave transmission in one-dimensional helicoidal phononic crystals in a shape similar to DNA structures. These helicoidal architectures allow slanted nonlinear contact among cylindrical constituents, and the relative torsional movements can dynamically tune the contact stiffness between neighboring cylinders. This results in cross-talking between in-plane torsional and out-of-plane longitudinal waves. We numerically demonstrate their versatile wave mixing and controllable dispersion behavior in both wavenumber and frequency domains. Based on this principle, a suggestion toward an acoustic configuration bearing parallels to a transistor is further proposed, in which longitudinal waves can be switched on and off through torsional waves.", "doi": "10.1103/PhysRevE.90.053201", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2014-11", "series_number": "5", "volume": "90", "issue": "5", "pages": "Art. No. 053201" }, { "id": "authors:kzcd1-7pn59", "collection": "authors", "collection_id": "kzcd1-7pn59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141205-092240119", "type": "article", "title": "Local to Extended Transitions of Resonant Defect Modes", "author": [ { "family_name": "Lydon", "given_name": "Joseph", "clpid": "Lydon-J" }, { "family_name": "Serra-Garcia", "given_name": "Marc", "clpid": "Serra-Garcia-M" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the localized modes created by introducing a resonant defect in a mechanical lattice. We find that modes introduced by resonant defects have profiles that can be tuned from being extremely localized to totally delocalized by an external force. This is in direct contrast with modes introduced by traditional mass or stiffness defects, in which the modes' profiles stay constant. We present an analytical model for resonant defects in one-dimensional nonlinear lattices, computationally demonstrate the equivalent effect in a two-dimensional lattice, and experimentally observe the mode profiles in a granular crystal. While our study is concerned with nonlinear mechanical lattices, the generality of our model suggests that the same effect should be present in other types of periodic lattices.", "doi": "10.1103/PhysRevLett.113.185503", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2014-10-29", "series_number": "18", "volume": "113", "issue": "18", "pages": "Art. No. 185503" }, { "id": "authors:ytkbm-v4572", "collection": "authors", "collection_id": "ytkbm-v4572", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141204-092151322", "type": "article", "title": "Granular acoustic switches and logic elements", "author": [ { "family_name": "Li", "given_name": "Feng", "clpid": "Li-Feng" }, { "family_name": "Anzel", "given_name": "Paul", "clpid": "Anzel-P" }, { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Kevrekidis", "given_name": "Panayotis G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Electrical flow control devices are fundamental components in electrical appliances and computers; similarly, optical switches are essential in a number of communication, computation and quantum information-processing applications. An acoustic counterpart would use an acoustic (mechanical) signal to control the mechanical energy flow through a solid material. Although earlier research has demonstrated acoustic diodes or circulators, no acoustic switches with wide operational frequency ranges and controllability have been realized. Here we propose and demonstrate an acoustic switch based on a driven chain of spherical particles with a nonlinear contact force. We experimentally and numerically verify that this switching mechanism stems from a combination of nonlinearity and bandgap effects. We also realize the OR and AND acoustic logic elements by exploiting the nonlinear dynamical effects of the granular chain. We anticipate these results to enable the creation of novel acoustic devices for the control of mechanical energy flow in high-performance ultrasonic devices.", "doi": "10.1038/ncomms6311", "issn": "2041-1723", "publisher": "Nature Publishing Group", "publication": "Nature Communications", "publication_date": "2014-10", "series_number": "10", "volume": "5", "issue": "10", "pages": "Art. No. 5311" }, { "id": "authors:sx8f6-57n04", "collection": "authors", "collection_id": "sx8f6-57n04", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141016-100606616", "type": "article", "title": "An Experimental Technique for the Dynamic Characterization of Soft Complex Materials", "author": [ { "family_name": "Thevamaran", "given_name": "R.", "orcid": "0000-0001-5058-6167", "clpid": "Thevamaran-R" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We describe an experimental technique to study the dynamic behavior of complex soft materials, based on high-speed microscopic imaging and direct measurements of dynamic forces and deformations. The setup includes high sensitivity dynamic displacement measurements based on geometric moir\u00e9 interferometry and high-speed imaging for in-situ, full-field visualization of the complex micro-scale dynamic deformations. The method allows extracting dynamic stress-strain profiles both from the moir\u00e9 interferometry and from the high-speed microscopic imaging. We discuss the advantages of using these two complementing components concurrently. We use this technique to study the dynamic response of vertically aligned carbon nanotube foams subjected to impact loadings at variable deformation rates. The same technique can be used to study other micro-structured materials and complex hierarchical structures.", "doi": "10.1007/s11340-014-9896-9", "issn": "0014-4851", "publisher": "Springer", "publication": "Experimental Mechanics", "publication_date": "2014-10", "series_number": "8", "volume": "54", "issue": "8", "pages": "1319-1328" }, { "id": "authors:spmwp-wa455", "collection": "authors", "collection_id": "spmwp-wa455", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141113-084329319", "type": "article", "title": "Acoustic Fresnel lenses with extraordinary transmission", "author": [ { "family_name": "Moler\u00f3n", "given_name": "Miguel", "clpid": "Moler\u00f3n-M" }, { "family_name": "Serra-Garcia", "given_name": "Marc", "clpid": "Serra-Garcia-M" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate numerically and experimentally highly efficient acoustic lenses based on the principle of extraordinary acoustic transmission. We study circular, flat lenses composed of perforated air channels. The geometry is similar to binary Fresnel lenses, and the lenses exploit several resonance mechanisms to enhance the transmission, such as Fabry\u2013Perot resonances in the channels and cavity resonances on the lens surface. The proposed lenses are able to transmit up to 83% of the incident energy and generate sharp focusing with very high amplification (up to 16\u2009dB experimentally). Furthermore, the resulting lenses are thinner than other designs providing similar performance, making them ideal candidates for application in acoustic imaging and medical diagnostics.", "doi": "10.1063/1.4896276", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2014-09-15", "series_number": "11", "volume": "105", "issue": "11", "pages": "Art. No. 114109" }, { "id": "authors:e5rjy-sq679", "collection": "authors", "collection_id": "e5rjy-sq679", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140926-083716624", "type": "article", "title": "Dynamics of periodic mechanical structures containing bistable elastic elements: From elastic to solitary wave propagation", "author": [ { "family_name": "Nadkarni", "given_name": "Neel", "clpid": "Nadkarni-N" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Kochmann", "given_name": "Dennis M.", "orcid": "0000-0002-9112-6615", "clpid": "Kochmann-D-M" } ], "abstract": "We investigate the nonlinear dynamics of a periodic chain of bistable elements consisting of masses connected by elastic springs whose constraint arrangement gives rise to a large-deformation snap-through instability. We show that the resulting negative-stiffness effect produces three different regimes of (linear and nonlinear) wave propagation in the periodic medium, depending on the wave amplitude. At small amplitudes, linear elastic waves experience dispersion that is controllable by the geometry and by the level of precompression. At moderate to large amplitudes, solitary waves arise in the weakly and strongly nonlinear regime. For each case, we present closed-form analytical solutions and we confirm our theoretical findings by specific numerical examples. The precompression reveals a class of wave propagation for a partially positive and negative potential. The presented results highlight opportunities in the design of mechanical metamaterials based on negative-stiffness elements, which go beyond current concepts primarily based on linear elastic wave propagation. Our findings shed light on the rich effective dynamics achievable by nonlinear small-scale instabilities in solids and structures.", "doi": "10.1103/PhysRevE.90.023204", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2014-08-22", "series_number": "2", "volume": "90", "issue": "2", "pages": "Art. No. 023204" }, { "id": "authors:db3y3-htc97", "collection": "authors", "collection_id": "db3y3-htc97", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140811-084943267", "type": "article", "title": "Traveling waves in 2D hexagonal granular crystal lattices", "author": [ { "family_name": "Leonard", "given_name": "A.", "clpid": "Leonard-Andrea-B" }, { "family_name": "Chong", "given_name": "C.", "clpid": "Chong-C" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "This study describes the dynamic response of a two-dimensional hexagonal packing of uncompressed stainless steel spheres excited by localized impulsive loadings. The dynamics of the system are modeled using the Hertzian normal contact law. After the initial impact strikes the system, a characteristic wave structure emerges and continuously decays as it propagates through the lattice. Using an extension of the binary collision approximation for one-dimensional chains, we predict its decay rate, which compares well with numerical simulations and experimental data. While the hexagonal lattice does not support constant speed traveling waves, we provide scaling relations that characterize the directional power law decay of the wave velocity for various angles of impact. Lastly, we discuss the effects of weak disorder on the directional amplitude decay rates.", "doi": "10.1007/s10035-014-0487-3", "pmcid": "PMC4819042", "issn": "1434-7636", "publisher": "Springer", "publication": "Granular Matter", "publication_date": "2014-08", "series_number": "4", "volume": "16", "issue": "4", "pages": "531-542" }, { "id": "authors:dgnw4-pnz92", "collection": "authors", "collection_id": "dgnw4-pnz92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141027-072323994", "type": "article", "title": "Geometry-Induced Mechanical Properties of Carbon Nanotube Foams", "author": [ { "family_name": "Lattanzi", "given_name": "Ludovica", "clpid": "Lattanza-L" }, { "family_name": "De Nardo", "given_name": "Luigi", "orcid": "0000-0002-7492-6012", "clpid": "De-Nardo-L" }, { "family_name": "Raney", "given_name": "Jordan R.", "clpid": "Raney-J-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Carbon nanotube (CNT) foams have unmatched energy absorption properties derived from their complex hierarchical structure. The control of the micro-scale geometry of these foams allows tuning their behavior to specific application-driven needs. Geometrical structures in CNT foams are obtained by synthesizing CNTs on substrates patterned with different growth templates: circles, lines and concentric rings. To study the effects of the microstructural geometry on the bulk mechanical response of the foams, the samples are tested under cyclic quasi-static compressive deformation (up to 50% strain). The geometry of the patterns plays a fundamental role on the samples' macroscopic energy absorption capability, maximum stress, and strain recovery. Patterned CNT structures demonstrated mechanical properties comparable or improved over non-patterned, bulk CNT foams, but with much lower density. Quasi-static compressive tests performed on different patterned structures with the same effective density (\u03c1\u2009=\u20090.02\u2009g\u2009cm^(\u22123)) exhibit considerably different responses. For example, the stress reached by foams patterned in concentric rings is \u224815 times higher than that observed for pillars and lines. The results show how the mechanical response of CNT foams can be tailored by varying the CNT microstructural architecture.", "doi": "10.1002/adem.201300524", "issn": "1438-1656", "publisher": "Wiley Verlag", "publication": "Advanced Engineering Materials", "publication_date": "2014-08", "series_number": "8", "volume": "16", "issue": "8", "pages": "1026-1031" }, { "id": "authors:2gv5f-31k84", "collection": "authors", "collection_id": "2gv5f-31k84", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140711-134431155", "type": "article", "title": "Effect of fluid medium on mechanical behavior of carbon nanotube foam", "author": [ { "family_name": "Misra", "given_name": "Abha", "clpid": "Misra-A" }, { "family_name": "Kumar", "given_name": "Praveen", "clpid": "Kumar-P" }, { "family_name": "Raney", "given_name": "Jordan R.", "clpid": "Raney-J-R" }, { "family_name": "Singhal", "given_name": "Anish", "clpid": "Singhal-A" }, { "family_name": "Lattanzi", "given_name": "Ludovica", "clpid": "Lattanza-L" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "This study reports the constitutive response and energy absorption capabilities of fluid-impregnated carbon nanotube (CNT) foams under compressive loading as a function of fluid viscosity and loading rates. At all strain rates tested, we observe two characteristic regimes: below a critical value, increasing fluid viscosity increases the load bearing and energy absorption capacities; after a critical value of the fluid's viscosity, we observe a rapid decrease in the systems' mechanical performance. For a given fluid viscosity, the load bearing capacity of the structure slightly decreases with strain rate. A phenomenological model, accounting for fluid-CNT interaction, is developed to explain the observed mechanical behavior.", "doi": "10.1063/1.4881843", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2014-06-02", "series_number": "22", "volume": "104", "issue": "22", "pages": "Art. No. 221910" }, { "id": "authors:wgm4j-x0s50", "collection": "authors", "collection_id": "wgm4j-x0s50", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140303-133811401", "type": "article", "title": "Thin Films with Ultra-low Thermal Expansion", "author": [ { "family_name": "Yamamoto", "given_name": "Namoki", "clpid": "Yamamoto-Namoki" }, { "family_name": "Gdoutos", "given_name": "Eleftherios", "clpid": "Gdoutos-E" }, { "family_name": "Toda", "given_name": "Risaku", "clpid": "Toda-Risaku" }, { "family_name": "White", "given_name": "Victor", "clpid": "White-V" }, { "family_name": "Manohara", "given_name": "Harish", "clpid": "Manohara-Harish-M" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Ultra-low coefficient of thermal expansion (CTE) is an elusive property, and narrow temperature ranges of operation and poor mechanical properties limit the use of conventional materials with low CTE. We structured a periodic micro-array of bi-metallic cells to demonstrate ultra-low effective CTE with a wide temperature range. These engineered tunable CTE thin film can be applied to minimize thermal fatigue and failure of optics, semiconductors, biomedical sensors, and solar energy applications.", "doi": "10.1002/adma.201304997", "issn": "0935-9648", "publisher": "Wiley", "publication": "Advanced Materials", "publication_date": "2014-05-21", "series_number": "19", "volume": "26", "issue": "19", "pages": "3076-3080" }, { "id": "authors:e99xq-b0b83", "collection": "authors", "collection_id": "e99xq-b0b83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140703-125623342", "type": "article", "title": "Solitary waves in a chain of repelling magnets", "author": [ { "family_name": "Moler\u03ccn", "given_name": "Miguel", "clpid": "Moler\u03ccn-M" }, { "family_name": "Leonard", "given_name": "Andrea", "clpid": "Leonard-Andrea-B" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study experimentally, numerically, and theoretically the dynamics of a one dimensional array of repelling magnets. We demonstrate that such systems support solitary waves with a profile and propagation speed that depend on the amplitude. The system belongs to the kind of nonlinear lattices studied in [Friesecke and Matthies, Physica D 171, 211\u2013220 (2002)] and exhibits a sech^2 profile in the low energy regime and atomic scale localization in the high energy regime. Such systems may find potential applications in the design of novel devices for shock absorption, energy localization and focusing. Furthermore, due to the similarity of the magnetic potential with the potentials governing atomic forces, the system could be used for a better understanding of important problems in physics and chemistry.", "doi": "10.1063/1.4872252", "issn": "0021-8979", "publisher": "American Institute of Physics", "publication": "Journal of Applied Physics", "publication_date": "2014-05-14", "series_number": "18", "volume": "115", "issue": "18", "pages": "Art. No. 184901" }, { "id": "authors:hd16p-ar317", "collection": "authors", "collection_id": "hd16p-ar317", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140404-111704700", "type": "article", "title": "Strain-rate-dependent model for the dynamic compression of elastoplastic spheres", "author": [ { "family_name": "Burgoyne", "given_name": "Hayden A.", "clpid": "Burgoyne-H-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We present a force-displacement contact model for the compressive loading of elastoplastic spheres. This model builds from the well known Hertz contact law for elastic, quasistatic compression to incorporate a material's strain-rate-dependent plasticity in order to describe collisions between particles. In the quasistatic regime, finite-element analysis is used to derive an empirical function of the material properties. A Johnson-Cook strain rate dependence is then included into the model to study dynamic effects. We validate the model using split Hopkinson bar experiments and show that the model can accurately simulate the force-displacement response of strain-rate-dependent elastoplastic spheres during dynamic compression and unloading.", "doi": "10.1103/PhysRevE.89.032203", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2014-03-12", "series_number": "3", "volume": "89", "issue": "3", "pages": "Art. No. 032203" }, { "id": "authors:md4gb-keb02", "collection": "authors", "collection_id": "md4gb-keb02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160316-133318246", "type": "monograph", "title": "Locally Resonant Granular Chain", "author": [ { "family_name": "Bonanomi", "given_name": "Luca", "clpid": "Bonanomi-L" }, { "family_name": "Theocharis", "given_name": "Georgios", "clpid": "Theocharis-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We report the design and testing of a tunable and nonlinear mechanical metamaterial, called locally resonant granular chain. It consists of a one-dimensional array of hollow spherical particles in contact, containing local resonators. The resonant particles are made of an aluminium outer spherical shell and a steel inner mass connected by a polymeric plastic structure acting as a spring. We characterize the linear spectra of the individual particles and of one-dimensional arrays of particles using theory, numerical analysis, and experiments. A wide band gap is observed as well as tunability of the dispersive spectrum by changing the applied static load. Finally, we experimentally explore the nonlinear dynamics of the resonant particles. By using nonlinear acoustical techniques, we reveal a complex, nonclassical nonlinear dynamics.", "doi": "10.48550/arXiv.1403.1052", "publication_date": "2014-03-05" }, { "id": "authors:swpwt-0pp12", "collection": "authors", "collection_id": "swpwt-0pp12", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140516-143830717", "type": "article", "title": "Damped-driven granular chains: An ideal playground for dark breathers and multibreathers", "author": [ { "family_name": "Chong", "given_name": "C.", "clpid": "Chong-Christopher" }, { "family_name": "Li", "given_name": "F.", "clpid": "Li-Feng" }, { "family_name": "Yang", "given_name": "J.", "clpid": "Yang-Jinkyu" }, { "family_name": "Williams", "given_name": "M. O.", "clpid": "Williams-M-O" }, { "family_name": "Kevrekidis", "given_name": "I. G.", "clpid": "Kevrekidis-I-G" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "By applying an out-of-phase actuation at the boundaries of a uniform chain of granular particles, we demonstrate experimentally that time-periodic and spatially localized structures with a nonzero background (so-called dark breathers) emerge for a wide range of parameter values and initial conditions. We demonstrate a remarkable control over the number of breathers within the multibreather pattern that can be \"dialed in\" by varying the frequency or amplitude of the actuation. The values of the frequency (or amplitude) where the transition between different multibreather states occurs are predicted accurately by the proposed theoretical model, which is numerically shown to support exact dark breather and multibreather solutions. Moreover, we visualize detailed temporal and spatial profiles of breathers and, especially, of multibreathers using a full-field probing technology and enable a systematic favorable comparison among theory, computation, and experiments. A detailed bifurcation analysis reveals that the dark and multibreather families are connected in a \"snaking\" pattern, providing a roadmap for the identification of such fundamental states and their bistability in the laboratory.", "doi": "10.1103/PhysRevE.89.032924", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2014-03", "series_number": "3", "volume": "89", "issue": "3", "pages": "Art. No. 032924" }, { "id": "authors:3jw1y-6hd64", "collection": "authors", "collection_id": "3jw1y-6hd64", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140214-104838036", "type": "article", "title": "Experimental realization of a nonlinear acoustic lens with a tunable focus", "author": [ { "family_name": "Donahue", "given_name": "Carly M.", "clpid": "Donahue-C-M" }, { "family_name": "Anzel", "given_name": "Paul W. J.", "clpid": "Anzel-P-W-J" }, { "family_name": "Bonanomi", "given_name": "Luca", "clpid": "Bonanomi-L" }, { "family_name": "Keller", "given_name": "Thomas A.", "clpid": "Keller-T-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We realize a nonlinear acoustic lens composed of a two-dimensional array of sphere chains interfaced with water. The chains are able to support solitary waves which, when interfaced with a linear medium, transmit compact pulses with minimal oscillations. When focused, the lens is able to produce compact pressure pulses of high amplitude, the \"sound bullets.\" We demonstrate that the focal point can be controlled via pre-compression of the individual chains, as this changes the wave speed within them. The experimental results agree well both spatially and temporally with analytical predictions over a range of focus locations.", "doi": "10.1063/1.4857635", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2014-01-06", "series_number": "1", "volume": "104", "issue": "1", "pages": "Art. No. 014103" }, { "id": "authors:r7dn7-8gc26", "collection": "authors", "collection_id": "r7dn7-8gc26", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160303-151759634", "type": "book_section", "title": "Fabrication and Characterization of Bi-metallic, Structured Films with Ultra-low Thermal Expansion", "book_title": "Experimental Mechanics of Composite, Hybrid, and Multifunctional Materials", "author": [ { "family_name": "Yamamoto", "given_name": "Namiko", "clpid": "Yamamoto-Namiko" }, { "family_name": "Gdoutos", "given_name": "Eleftherios", "clpid": "Gdoutos-E" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "contributor": [ { "family_name": "Tandon", "given_name": "G. P.", "clpid": "Tandon-G-P" }, { "family_name": "Tekalur", "given_name": "Srinivasan Arjun", "clpid": "Tekalur-S-A" }, { "family_name": "Ralph", "given_name": "Carter", "clpid": "Ralph-C" }, { "family_name": "Sottos", "given_name": "Nancy R.", "clpid": "Sottos-N-R" }, { "family_name": "Blaiszik", "given_name": "Benjamin", "clpid": "Blaiszik-B" } ], "abstract": "We fabricate and characterize bi-metallic structured thin films (~1 um thick) with ultra-low effective coefficient of thermal expansion (CTE). The films consist of a periodic array of aluminum (Al) hexagonal plates attached to a titanium (Ti) frame. In this designed discontinuous geometry, the self-standing films present ultra-low effective CTE through local release of the thermal strains by relative rotation of the lattice elements. We fabricated this structured film by a combination of conventional micro-fabrication process steps, and we measured its CTE as ultra-low (\u22120.6 \u00d7 10^(\u22126)/\u00b0C) using 3D digital image correlation. This new thin film can lead to the creation of low-cost, adaptive structures that operate in extreme thermal environments, such as reflective layers for space telescopes.", "doi": "10.1007/978-3-319-00873-8_11", "isbn": "978-3-319-00872-1", "publication_date": "2014", "pages": "85-88" }, { "id": "authors:knt59-yf755", "collection": "authors", "collection_id": "knt59-yf755", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131212-083713497", "type": "article", "title": "Directed ratchet transport in granular chains", "author": [ { "family_name": "Berardi", "given_name": "V.", "clpid": "Berardi-V" }, { "family_name": "Lydon", "given_name": "J.", "clpid": "Lydon-J" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Carretero-Gonz\u00e1lez", "given_name": "R.", "clpid": "Carretero-Gonz\u00e1lez-R" } ], "abstract": "Directed-ratchet transport (DRT) in a one-dimensional lattice of spherical beads, which serves as a prototype for granular chains, is investigated. We consider a system where the trajectory of the central bead is prescribed by a biharmonic forcing function with broken time-reversal symmetry. By comparing the mean integrated force of beads equidistant from the forcing bead, two distinct types of directed transport can be observed\u2014spatial and temporal DRT. Based on the value of the frequency of the forcing function relative to the cutoff frequency, the system can be categorized by the presence and magnitude of each type of DRT. Furthermore, we investigate and quantify how varying additional parameters such as the biharmonic weight affects DRT velocity and magnitude. Finally, friction is introduced into the system and is found to significantly inhibit spatial DRT. In fact, for sufficiently low forcing frequencies, the friction may even induce a switching of the DRT direction.", "doi": "10.1103/PhysRevE.88.052202", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2013-11-15", "series_number": "5", "volume": "88", "issue": "5", "pages": "Art. No. 052202" }, { "id": "authors:s3rtd-zhe31", "collection": "authors", "collection_id": "s3rtd-zhe31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131121-131707051", "type": "article", "title": "Thin and Thermally Stable Periodic Metastructures", "author": [ { "family_name": "Gdoutos", "given_name": "E.", "clpid": "Gdoutos-E" }, { "family_name": "Shapiro", "given_name": "A. A.", "clpid": "Shapiro-A-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We design, fabricate, and test thin thermally stable metastructures consisting of bi-metallic unit cells and show how the coefficient of thermal expansion (CTE) of these metastructures can be finely and coarsely tuned by varying the CTE of the constituent materials and the unit cell geometry. Planar and three-dimensional finite element method modeling (FEM) is used to drive our design and inform experiments, and predict the response of these metastructures. We develop a robust experimental fabrication procedure in order to fabricate thermally stable samples with high aspect ratios. We use digital image correlation (DIC) and an infrared camera to experimentally measure displacement and temperature during testing and compute the CTE of our samples. The samples, composed of an aluminum core and an external titanium frame, exhibit a CTE of 2.6 ppm/\u00b0C, which is significantly lower than either constituent. These unit cells can be assembled over a large area to create thin low-CTE foils. Finally, we demonstrate how the approach developed in this work can be used to fabricate metastructures with CTE's ranging from \u22123.6 ppm/\u00b0C to 8.4 ppm/\u00b0C.", "doi": "10.1007/s11340-013-9748-z", "issn": "0014-4851", "publisher": "Society for Experimental Mechanics", "publication": "Experimental Mechanics", "publication_date": "2013-11", "series_number": "9", "volume": "53", "issue": "9", "pages": "1735-1742" }, { "id": "authors:1eqve-t6282", "collection": "authors", "collection_id": "1eqve-t6282", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131101-105544944", "type": "article", "title": "Effect of morphology on the strain recovery of vertically aligned carbon nanotube arrays: An in situ study", "author": [ { "family_name": "Pathak", "given_name": "Siddhartha", "clpid": "Pathak-S" }, { "family_name": "Raney", "given_name": "Jordan R.", "clpid": "Raney-J-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We report on the distinctly different mechanical responses of two vertically aligned carbon nanotube (VACNT) films, subjected to large displacement (up to 70 \u03bcm) flat punch indentations. The VACNT films were synthesized using the same chemical vapor deposition (CVD) technique but for varying reaction times, which resulted in their different thicknesses (480 and 160 \u03bcm, respectively) and morphologies. In situ tests reveal that the shorter, more aligned VACNT film deforms via an instantaneous vertical shearing of the material directly underneath the indenter tip, which is manifested as a rapid displacement burst in the load\u2013displacement response when tested at rates of 100 nm/s and above. The resultant buckles were of a more permanent nature leading to their low recoverability (22\u201340%). In contrast, we find the thicker, more tortuous VACNT film to show a higher (\u223c80%) recovery and a more compliant response. These differences in the mechanical response of the VACNTs are discussed in the framework of foam-like deformation with a particular emphasis on their different morphological features, namely density and tortuosity.", "doi": "10.1016/j.carbon.2013.06.083", "issn": "0008-6223", "publisher": "Elsevier", "publication": "Carbon", "publication_date": "2013-11", "volume": "63", "pages": "303-316" }, { "id": "authors:p3ers-1hc87", "collection": "authors", "collection_id": "p3ers-1hc87", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131106-073149674", "type": "article", "title": "Granular metamaterials for vibration mitigation", "author": [ { "family_name": "Gantzounis", "given_name": "G.", "clpid": "Gantzounis-G" }, { "family_name": "Serra-Garcia", "given_name": "M.", "clpid": "Serra-Garcia-M" }, { "family_name": "Homma", "given_name": "K.", "clpid": "Homma-K" }, { "family_name": "Mendoza", "given_name": "J. M.", "clpid": "Mendoza-J-M" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Acoustic metamaterials that allow low-frequency band gaps are interesting for many practical engineering applications, where vibration control and sound insulation are necessary. In most prior studies, the mechanical response of these structures has been described using linear continuum approximations. In this work, we experimentally and theoretically address the formation of low-frequency band gaps in locally resonant granular crystals, where the dynamics of the system is governed by discrete equations. We investigate the quasi-linear behavior of such structures. The analysis shows that a stopband can be introduced at about one octave lower frequency than in materials without local resonances. Broadband and multi-frequency stopband characteristics can also be achieved by strategically tailoring the non-uniform local resonance parameters.", "doi": "10.1063/1.4820521", "issn": "0021-8979", "publisher": "American Institute of Physics", "publication": "Journal of Applied Physics", "publication_date": "2013-09-07", "series_number": "9", "volume": "114", "issue": "9", "pages": "Art. No. 093514" }, { "id": "authors:zgj85-qsk87", "collection": "authors", "collection_id": "zgj85-qsk87", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170705-153021095", "type": "book_section", "title": "Site-Specific Diagnostic Evaluation of Hard Biological Tissues Using Solitary Waves", "book_title": "Mechanics of Biological Systems and Materials", "author": [ { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Sangiorgio", "given_name": "Sophia N.", "clpid": "Sangiorgio-S-N" }, { "family_name": "Borkowski", "given_name": "Sean L.", "clpid": "Borkowski-S-L" }, { "family_name": "Ebramzadeh", "given_name": "Edward", "clpid": "Ebramzadeh-E" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "contributor": [ { "family_name": "Barthelat", "given_name": "Fran\u00e7ois", "clpid": "Barthelat-F" }, { "family_name": "Zavattieri", "given_name": "Pablo", "clpid": "Zavattieri-P" }, { "family_name": "Korach", "given_name": "Chad S.", "clpid": "Korach-C-S" }, { "family_name": "Prorok", "given_name": "Barton C.", "clpid": "Prorok-B-C" }, { "family_name": "Grande-Allen", "given_name": "K. Jane", "clpid": "Grande-Allen-K-J" } ], "abstract": "We perform site-specific diagnostic evaluation of hard biological tissues via highly nonlinear solitary waves. Solitary waves are compact-supported tunable pulses with extremely high energy density, which can be efficiently formed in a chain of ordered granular particles defined as 1D granular crystals. We transmit a single pulse of solitary waves into specific areas of artificial biological systems via direct mechanical contact with a granular crystal sensor. We then record the solitary waves backscattered from a targeted bone area to assess its mechanical stiffness. By taking advantage of the coupling between nonlinear granular media and biological systems, we demonstrate that reflected solitary waves are highly sensitive to site-specific mechanical properties of hard biological tissues. The efficacy of the diagnostic approach is investigated by comparing the stiffness measurements with nominal elastic moduli of polyurethane foams that mimic osteoporotic bone. We also perform numerical investigations via a discrete element (DE) model, simulating propagation and attenuation of solitary waves at the interfaces. The site-specific evaluation technique via solitary waves has the potential for clinical applications, such as assisting appropriate intraoperative decision during joint replacement or spinal surgery for better surgical outcome.", "doi": "10.1007/978-3-319-00777-9_27", "isbn": "978-3-319-00776-2", "publisher": "Springer", "place_of_publication": "Cham", "publication_date": "2013-07-21", "pages": "185-189" }, { "id": "authors:3ve3j-aaq48", "collection": "authors", "collection_id": "3ve3j-aaq48", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130826-112439730", "type": "article", "title": "Frequency bands of strongly nonlinear homogeneous granular systems", "author": [ { "family_name": "Lydon", "given_name": "Joseph", "clpid": "Lydon-J" }, { "family_name": "Jayaprakash", "given_name": "K. R.", "clpid": "Jayaprakash-K-R" }, { "family_name": "Ngo", "given_name": "Duc", "clpid": "Ngo-Duc" }, { "family_name": "Starosvetsky", "given_name": "Yuli", "clpid": "Starosvetsky-Y" }, { "family_name": "Vakakis", "given_name": "Alexander F.", "clpid": "Vakakis-A-F" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Recent numerical studies on an infinite number of identical spherical beads in Hertzian contact showed the presence of frequency bands [ Jayaprakash, Starosvetsky, Vakakis, Peeters and Kerschen Nonlinear Dyn. 63 359 (2011)]. These bands, denoted here as propagation and attenuation bands (PBs and ABs), are typically present in linear or weakly nonlinear periodic media; however, their counterparts are not intuitive in essentially nonlinear periodic media where there is a complete lack of classical linear acoustics, i.e., in \"sonic vacua.\" Here, we study the effects of PBs and ABs on the forced dynamics of ordered, uncompressed granular systems. Through numerical and experimental techniques, we find that the dynamics of these systems depends critically on the frequency and amplitude of the applied harmonic excitation. For fixed forcing amplitude, at lower frequencies, the oscillations are large in amplitude and governed by strongly nonlinear and nonsmooth dynamics, indicating PB behavior. At higher frequencies the dynamics is weakly nonlinear and smooth, in the form of compressed low-amplitude oscillations, indicating AB behavior. At the boundary between the PB and the AB large-amplitude oscillations due to resonance occur, giving rise to collisions between beads and chaotic dynamics; this renders the forced dynamics sensitive to initial and forcing conditions, and hence unpredictable. Finally, we study asymptotically the near field standing wave dynamics occurring for high frequencies, well inside the AB.", "doi": "10.1103/PhysRevE.88.012206", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2013-07-19", "series_number": "1", "volume": "88", "issue": "1", "pages": "Art. No. 012206" }, { "id": "authors:ws43v-gb498", "collection": "authors", "collection_id": "ws43v-gb498", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130605-085347344", "type": "article", "title": "Pressure-activated microsyringe composite scaffold of poly(L-lactic acid) and carbon nanotubes for bone tissue engineering", "author": [ { "family_name": "Vozzi", "given_name": "Giovanni", "clpid": "Vozzi-G" }, { "family_name": "Corallo", "given_name": "Claudio", "clpid": "Corallo-C" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Tissue engineering is an innovative interdisciplinary field in which bioengineers and life scientists try to regenerate and reproduce natural tissues through the use of biodegradable structures, called scaffolds, with the aim of mimicking the specific tissue extracellular matrix (ECM). Carbon nanotubes (CNTs) offer a natural platform for obtaining composite microfabricated scaffolds thanks to their excellent mechanical properties and their good biocompatibility. In this study, we microfabricated three-dimensional (3D) scaffolds by mixing poly(L-lactic acid) (PLLA) and multiwalled carbon nanotubes (MWCNTs) for bone tissue engineering. We measured their mechanical properties and studied their biocompatibility with human fetal osteoblasts (hFOB 1.19). The 3D microfabricated PLLA/MWCNTs nanocomposite scaffolds showed higher stiffness and cell viability than the pure 3D microfabricated PLLA scaffolds. The results of this preliminary work suggest that biopolymer/CNT microcomposites and nanocomposites could be used as effective building blocks to replace ECMs in bone tissue engineering applications. The final goal is the creation of innovative scaffolds for implants and tissue regeneration.", "doi": "10.1002/app.38235", "issn": "0021-8995", "publisher": "Wiley-Blackwell", "publication": "Journal of Applied Polymer Science", "publication_date": "2013-07-15", "series_number": "2", "volume": "129", "issue": "2", "pages": "528-536" }, { "id": "authors:y61py-y7g24", "collection": "authors", "collection_id": "y61py-y7g24", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130712-084948584", "type": "article", "title": "Rate-independent dissipation and loading direction effects in compressed carbon nanotube arrays", "author": [ { "family_name": "Raney", "given_name": "J. R.", "clpid": "Raney-J-R" }, { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Arrays of nominally-aligned carbon nanotubes (CNTs) under compression deform locally via buckling, exhibit a foam-like, dissipative response, and can often recover most of their original height. We synthesize millimeter-scale CNT arrays and report the results of compression experiments at different strain rates, from 10^(\u22124) to 10^(\u22121) s^(\u22121), and for multiple compressive cycles to different strains. We observe that the stress\u2013strain response proceeds independently of the strain rate for all tests, but that it is highly dependent on loading history. Additionally, we examine the effect of loading direction on the mechanical response of the system. The mechanical behavior is modeled using a multiscale series of bistable springs. This model captures the rate independence of the constitutive response, the local deformation, and the history-dependent effects. We develop here a macroscopic formulation of the model to represent a continuum limit of the mesoscale elements developed previously. Utilizing the model and our experimental observations we discuss various possible physical mechanisms contributing to the system's dissipative response.", "doi": "10.1088/0957-4484/24/25/255707", "issn": "0957-4484", "publisher": "IOP", "publication": "Nanotechnology", "publication_date": "2013-06-28", "series_number": "25", "volume": "24", "issue": "25", "pages": "Art. No. 255707" }, { "id": "authors:scw59-x2w78", "collection": "authors", "collection_id": "scw59-x2w78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130711-104241520", "type": "article", "title": "Propagation of highly nonlinear solitary waves in a curved\n granular chain", "author": [ { "family_name": "Cai", "given_name": "Luyao", "clpid": "Cai-Luyao" }, { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Rizzo", "given_name": "Piervincenzo", "clpid": "Rizzo-P" }, { "family_name": "Ni", "given_name": "Xianglei", "clpid": "Ni-Xianglei" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We assemble granular chains composed of spheres of uniform diameter in different curved configurations. We study the properties of highly nonlinear solitary waves traveling in the curved channels as a function of the curve angle and of the radius of curvature, using experiments and numerical simulations. We observe that solitary waves propagate robustly even under drastic deflection, such as 90\u2218 and 180\u2218 turns. When the solitary waves encounter a sharp turn with a radius of curvature as small as one spherical particle's diameter, we report the formation of secondary solitary waves resulting from the interaction with the guiding rail. We compare experimental results with numerical simulations based on a discrete element model that accounts for nonlinear and dissipative interactions between particles. This study demonstrates that granular chains are efficient wave-guides, even in complex geometrical configurations. Moreover, the findings in this study suggest that solitary waves could be used as novel information and/or energy carriers.", "doi": "10.1007/s10035-013-0414-z", "issn": "1434-5021", "publisher": "Springer", "publication": "Granular Matter", "publication_date": "2013-06", "series_number": "3", "volume": "15", "issue": "3", "pages": "357-366" }, { "id": "authors:x28fa-1gc23", "collection": "authors", "collection_id": "x28fa-1gc23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130805-110658753", "type": "article", "title": "Multiscale Mass-Spring Models of Carbon Nanotube Arrays Accounting for Mullins-like Behavior and Permanent Deformation", "author": [ { "family_name": "Blesgen", "given_name": "T.", "clpid": "Blesgen-T" }, { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Raney", "given_name": "J. R.", "clpid": "Raney-J-R" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Based on a one-dimensional discrete system of bistable springs, a mechanical model is introduced to describe plasticity and damage in carbon nanotube (CNT) arrays. The energetics of the mechanical system are investigated analytically, the stress-strain law is derived, and the mechanical dissipation is computed, both for the discrete case as well as for the continuum limit. An information-passing approach is developed that permits the investigation of macroscopic portions of the material. As an application, the simulation of a cyclic compression experiment on real CNT foam is performed, considering both the material response during the primary loading path from the virgin state and the damaged response after preconditioning.", "doi": "10.1137/12087311X", "issn": "1540-3459", "publisher": "Society for Industrial and Applied Mathematics", "publication": "Multiscale Modeling and Simulation", "publication_date": "2013-05-22", "series_number": "2", "volume": "11", "issue": "2", "pages": "545-565" }, { "id": "authors:1saz8-q2h23", "collection": "authors", "collection_id": "1saz8-q2h23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130516-133317881", "type": "article", "title": "Interaction of traveling waves with mass-with-mass defects within a Hertzian chain", "author": [ { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Vainchtein", "given_name": "A.", "clpid": "Vainchtein-A" }, { "family_name": "Serra Garcia", "given_name": "M.", "clpid": "Serra-Garcia-M" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the dynamic response of a granular chain of particles with a resonant inclusion (i.e., a particle attached to a harmonic oscillator, or a mass-with-mass defect). We focus on the response of granular chains excited by an impulse, with no static precompression. We find that the presence of the harmonic oscillator can be used to tune the transmitted and reflected energy of a mechanical pulse by adjusting the ratio between the harmonic resonator mass and the bead mass. Furthermore, we find that this system has the capability of asymptotically trapping energy, a feature that is not present in granular chains containing other types of defects. Finally, we study the limits of low and high resonator mass, and the structure of the reflected and transmitted pulses.", "doi": "10.1103/PhysRevE.87.042911", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2013-04", "series_number": "4", "volume": "87", "issue": "4", "pages": "Art. No. 042911" }, { "id": "authors:7d6f0-s6t21", "collection": "authors", "collection_id": "7d6f0-s6t21", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130509-102231427", "type": "article", "title": "Dark breathers in granular crystals", "author": [ { "family_name": "Chong", "given_name": "C.", "clpid": "Chong-Christopher" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Theocharis", "given_name": "G.", "clpid": "Theocharis-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We present a study of the existence, stability, and bifurcation structure of families of dark breathers in a one-dimensional uniform chain of spherical beads under static load. A defocusing nonlinear Schr\u00f6dinger equation (NLS) is derived for frequencies that are close to the edge of the phonon band and is used to construct targeted initial conditions for numerical computations. Salient features of the system include the existence of large amplitude solutions that emerge from the small amplitude solutions described by the NLS equation, and the presence of a nonlinear instability that, to the best of the authors' knowledge, has not been observed in classical Fermi-Pasta-Ulam lattices. Finally, it is also demonstrated that these dark breathers can be detected in a physically realistic experimental settings by merely actuating the ends of an initially at rest chain of beads and inducing destructive interference between their signals.", "doi": "10.1103/PhysRevE.87.042202", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2013-04", "series_number": "4", "volume": "87", "issue": "4", "pages": "Art. No. 042202" }, { "id": "authors:86k94-p3449", "collection": "authors", "collection_id": "86k94-p3449", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160303-152113967", "type": "book_section", "title": "Engineered thin films with ultra-low thermal expansion coefficient for deployable or deformable space structures", "book_title": "54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference", "author": [ { "family_name": "Yamamoto", "given_name": "Namiko", "clpid": "Yamamoto-Namiko" }, { "family_name": "Gdoutos", "given_name": "Eleftherios", "clpid": "Gdoutos-E" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We developed micro-structured thin films with ultra-low coefficient of thermal expansion. These low-weight, flexible, thermally stable films are expected to be a useful tool in aerospace applications, for example, as a reflective layers of deformable space telescope mirrors. The low-CTE films are composed of a Ti frame supporting hexagonal Al plates arranged in a two-dimensional periodic lattice. The effective CTE of these materials can be controlled by selecting the appropriate constitutent material properties of the frame and plates, and the geometry of the lattice. Aluminum and titanium were selected as constituent materials to create thin films with a CTE close to zero. The 2D bi-metallic lattice was microfabricated, and characterized for its thermal and optical functionalities. The effective CTE was confirmed to be ultra-low (-0.6\u00d710^(-6)/\u00b0C), and the imaging capability of this metallic layer was evaluated in the range of temperature from room temperature to 150 \u00b0C.", "doi": "10.2514/6.2013-1789", "isbn": "978-1-62410-223-3", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_publication": "Reston, VA", "publication_date": "2013-04", "pages": "Art. No. 2013-1789" }, { "id": "authors:gmpzt-20a46", "collection": "authors", "collection_id": "gmpzt-20a46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130506-073352642", "type": "article", "title": "Highly nonlinear solitary waves in chains of hollow spherical\n particles", "author": [ { "family_name": "Ngo", "given_name": "Duc", "clpid": "Ngo-Duc" }, { "family_name": "Griffiths", "given_name": "Stephane", "clpid": "Griffiths-S" }, { "family_name": "Khatri", "given_name": "Devvrath", "clpid": "Khatri-D" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the dynamic response of one- dimensional granular chains composed of uniform hollow spheres excited by an impulse, and we observe the formation and propagation of highly nonlinear solitary waves. We find that the dynamics of these solitary waves are different from the solitary waves forming in chains composed of uniform solid spheres, because of the changes in the contact interaction between particles. We study the quasi-static contact interaction between two hollows spheres using finite element (FE) simulations, and approximate their response as a power-law type function in the range of forces of interest for this work. The experimental data obtained by testing a chain of particles shows good agreement with theoretical predictions obtained using a long wavelength approximation, and with numerical simulations based on discrete particle and FE models. We also investigate the effect of hollow spheres' wall thickness on the dynamic response of the chains.", "doi": "10.1007/s10035-012-0377-5", "issn": "1434-7636", "publisher": "Springer", "publication": "Granular Matter", "publication_date": "2013-04", "series_number": "2", "volume": "15", "issue": "2", "pages": "149-155" }, { "id": "authors:w7jcx-8rw43", "collection": "authors", "collection_id": "w7jcx-8rw43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130411-103604540", "type": "article", "title": "Energy equipartition in two-dimensional granular systems with spherical intruders", "author": [ { "family_name": "Szelengowicz", "given_name": "I.", "clpid": "Szelengowicz-I" }, { "family_name": "Hasan", "given_name": "M. A.", "clpid": "Hasan-M-A" }, { "family_name": "Starosvetsky", "given_name": "Y.", "clpid": "Starosvetsky-Y" }, { "family_name": "Vakakis", "given_name": "A.", "clpid": "Vakakis-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the effects of a line of spherical interstitial particles (or intruders) placed between two adjacent uncompressed chains of larger particles in a square packing of spheres, using experiments and numerical simulations. We excite one of the chains of particles adjacent to the intruders with an impact and show how energy is transmitted across the system until equipartition is reached from the excited (or impacted) chain to the absorbing (or adjacent) chain. The coupling of the two chains, although a purely two-dimensional effect, is modeled by a simplified one-and-a-half-dimensional system in which transverse motions of the particles are neglected.", "doi": "10.1103/PhysRevE.87.032204", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2013-03-14", "series_number": "3", "volume": "87", "issue": "3", "pages": "Art. No. 032204" }, { "id": "authors:s7aep-a3z98", "collection": "authors", "collection_id": "s7aep-a3z98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130321-155442585", "type": "article", "title": "Frequency- and Amplitude-Dependent Transmission of Stress Waves in Curved One-Dimensional Granular Crystals Composed of Diatomic Particles", "author": [ { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the stress wave propagation in curved chains of particles (granular crystals) confined by bent elastic guides. We report the frequency- and amplitude-dependent filtering of transmitted waves in relation to various impact conditions and geometrical configurations. The granular crystals studied consist of alternating cylindrical and spherical particles pre-compressed with variable static loads. First, we excite the granular crystals with small-amplitude, broadband perturbations using a piezoelectric actuator to generate oscillatory elastic waves. We find that the linear frequency spectrum of the transmitted waves creates pass- and stop-bands in agreement with the theoretical dispersion relation, demonstrating the frequency-dependent filtering of input excitations through the diatomic granular crystals. Next, we excite high-amplitude nonlinear pulses in the crystals using striker impacts. Experimental tests verify the formation and propagation of highly nonlinear solitary waves that exhibit amplitude-dependent attenuation. We show that the wave propagation can be easily tuned by manipulating the pre-compression imposed to the chain or by varying the initial curvature of the granular chains. We use a combined discrete element (DE) and finite element (FE) numerical model to simulate the propagation of both dispersive linear waves and compactly-supported highly nonlinear waves. We find that the tunable, frequency- and amplitude-dependent filtering of the incoming signals results from the close interplay between the granular particles and the soft elastic media. The findings in this study suggest that hybrid structures composed of granular particles and linear elastic media can be employed as new passive acoustic filtering materials that selectively transmit or mitigate excitations in a desired range of frequencies and amplitudes.", "doi": "10.1007/s11340-012-9652-y", "issn": "0014-4851", "publisher": "Springer", "publication": "Experimental Mechanics", "publication_date": "2013-03", "series_number": "3", "volume": "53", "issue": "3", "pages": "469-483" }, { "id": "authors:f9km6-a1e59", "collection": "authors", "collection_id": "f9km6-a1e59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130321-154604673", "type": "article", "title": "Directional Wave Propagation in a Highly Nonlinear Square Packing of Spheres", "author": [ { "family_name": "Leonard", "given_name": "A.", "clpid": "Leonard-Andrea-B" }, { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We studied the dynamic response of a two-dimensional square packing of uncompressed stainless steel spheres excited by impulsive loadings. We developed a new experimental measurement technique, employing miniature tri-axial accelerometers, to determine the stress wave properties in the array resulting from both an in-plane and out-of-plane impact. Results from our numerical simulations, based on a discrete particle model, were in good agreement with the experimental results. We observed that the impulsive excitations were resolved into solitary waves traveling only through initially excited chains. The observed solitary waves were determined to have similar (Hertzian) properties to the extensively studied solitary waves supported by an uncompressed, uniform, one-dimensional chain of spheres. The highly directional response of this system could be used as a basis to design granular crystals with predetermined wave propagation paths capable of mitigating stress wave energy.", "doi": "10.1007/s11340-011-9544-6", "issn": "0014-4851", "publisher": "Springer", "publication": "Experimental Mechanics", "publication_date": "2013-03", "series_number": "3", "volume": "53", "issue": "3", "pages": "327-337" }, { "id": "authors:snjk6-ej855", "collection": "authors", "collection_id": "snjk6-ej855", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130228-124430510", "type": "article", "title": "Control of microstructural heterogeneities in carbon nanotube foams", "author": [ { "family_name": "Raney", "given_name": "Jordan R.", "clpid": "Raney-J-R" }, { "family_name": "Wang", "given_name": "Richard Y.", "clpid": "Wang-Richard-Y" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Arrays of aligned carbon nanotubes (CNTs) under compression are known to exhibit a dissipative hysteretic response similar to classical foams. Here, we control the microstructure of the arrays during synthesis using a variable supply of carbon source and catalyst. We control CNT alignment and density along the array height, creating bands of high- and low-density regions. We study the dynamic response of these materials and show the ability to tailor the location and extent of strain localization under compression. We show that the synthesis procedures described herein allow for construction of CNT arrays with improved protection and energy dissipation in impact tests.", "doi": "10.1016/j.carbon.2012.09.020", "issn": "0008-6223", "publisher": "Elsevier", "publication": "Carbon", "publication_date": "2013-02", "volume": "52", "pages": "193-200" }, { "id": "authors:5eg17-38m56", "collection": "authors", "collection_id": "5eg17-38m56", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130409-081751964", "type": "article", "title": "Hysteresis loops and multi-stability: From periodic orbits to chaotic dynamics (and back) in diatomic granular crystals", "author": [ { "family_name": "Hoogeboom", "given_name": "C.", "clpid": "Hoogeboom-C" }, { "family_name": "Man", "given_name": "Y.", "clpid": "Man-Y" }, { "family_name": "Boechler", "given_name": "N.", "clpid": "Boechler-N" }, { "family_name": "Theocharis", "given_name": "G.", "clpid": "Theocharis-G" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Kevrekidis", "given_name": "I. G.", "clpid": "Kevrekidis-I-G" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We consider a statically compressed diatomic granular crystal, consisting of alternating aluminum and steel spheres. The combination of dissipation, driving of the boundary, and intrinsic nonlinearity leads to complex dynamics. Through both numerical simulations and experiments, we find that the interplay of nonlinear surface modes with modes caused by the driver create the possibility, as the driving amplitude is increased, of limit cycle saddle-node bifurcations beyond which the dynamics of the system becomes chaotic. In this chaotic state, part of the applied energy can propagate through the chain. We also find that the chaotic branch depends weakly on the driving frequency, and speculate a connection between the chaotic dynamics with the gap openings between the spheres. Finally, we observe hysteretic dynamics and an interval of multi-stability involving stable periodic solutions and chaotic ones.", "doi": "10.1209/0295-5075/101/44003", "issn": "0295-5075", "publisher": "EDP Sciences", "publication": "Europhysics Letters", "publication_date": "2013-02", "series_number": "4", "volume": "101", "issue": "4", "pages": "Art. No. 44003" }, { "id": "authors:8vdzg-mmj37", "collection": "authors", "collection_id": "8vdzg-mmj37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130301-095933576", "type": "article", "title": "Modeling microscale instabilities in compressed carbon nanotube bundles using multistable spring models", "author": [ { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Raney", "given_name": "J. R.", "clpid": "Raney-J-R" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We formulate in situ parameter identification techniques for multistable spring models of compressed CNT bundles, which capture the sequential buckling through the height of the bundle, as well as the overall mechanical response. The proposed techniques are validated against a SEM-assisted compression experiment on a CNT pillar [1]. Using multi-spring models, we propose a 'microscopic' identification technique based on the determination of stress\u2013strain curves of vertical segments of the tested structure (featuring few micron height). We show that the in situ identified models can effectively reproduce the experimentally-observed stress\u2013strain response (single-spring models), and strain localization effects (multi-spring model), within a simple 1D framework.", "doi": "10.1016/j.compstruct.2012.09.013", "issn": "0263-8223", "publisher": "Elsevier", "publication": "Composite Structures", "publication_date": "2013-02", "volume": "96", "pages": "745-750" }, { "id": "authors:xwwby-03361", "collection": "authors", "collection_id": "xwwby-03361", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130118-104237894", "type": "article", "title": "Wave propagation in square granular crystals with spherical interstitial intruders", "author": [ { "family_name": "Szelengowicz", "given_name": "I.", "clpid": "Szelengowicz-I" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate the propagation and scattering of highly nonlinear waves in granular systems composed of spheres in contact arranged in a square packing, and study how the presence of small and light spherical interstitial defects, also referred to as intruders, affects the wave propagation. The effects of a single defect are investigated experimentally and compared to numerical simulations, showing very good quantitative agreement. Transmitted and scattered waves are formed, whose characteristics depend on the material properties of the defect in relation to the properties of the particles in the lattice. Experiments and numerical simulations reveal that stiffer defects are more efficient at redistributing energy outside the impacted chain and soft defects induce a localization of the energy at the defect. Finally, the effects of the presence of two defects, placed diagonally or aligned in the square packing are also investigated, as well as how their interaction depends on their relative positions.", "doi": "10.1103/PhysRevE.86.061306", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2012-12-12", "series_number": "6", "volume": "86", "issue": "6", "pages": "Art. No. 061306" }, { "id": "authors:s9a22-k0n30", "collection": "authors", "collection_id": "s9a22-k0n30", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121130-115544114", "type": "article", "title": "Monitoring the hydration of cement using highly nonlinear solitary waves", "author": [ { "family_name": "Ni", "given_name": "Xianglei", "clpid": "Ni-Xianglei" }, { "family_name": "Rizzo", "given_name": "Piervincenzo", "clpid": "Rizzo-P" }, { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Katri", "given_name": "Devvrath", "clpid": "Katri-D" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In this paper we present a nondestructive evaluation technique based on the propagation of highly nonlinear solitary waves (HNSWs) to monitor the hydration of cement. HNSWs are mechanical waves that can form and travel in highly nonlinear systems, such as one-dimensional chains of contacting spherical particles (i.e., granular crystals). In the present study, we use a granular crystal-based actuator/sensor to observe the solitary waves propagating to and from the mechanical interface between the transducer and a fresh gypsum cement sample. We hypothesize that the reflected HNSWs traveling along the crystal-based transducer are affected by the hydration process of the cement, and we assess the elastic modulus of the specimen in the localized region of the granular crystal contact. To verify the experimental results, we perform numerical simulations based on a simplified finite element model. The elastic properties of the cement specimen measured by the granular crystal transducer are compared with the compressive strength and the elastic modulus measurements obtained from destructive tests, conducted according to the ASTM C109. We observe good agreement between experiments and numerical simulations.", "doi": "10.1016/j.ndteint.2012.05.003", "issn": "0963-8695", "publisher": "Elsevier Ltd.", "publication": "NDT&E International", "publication_date": "2012-11", "volume": "52", "pages": "76-85" }, { "id": "authors:bs891-e2q53", "collection": "authors", "collection_id": "bs891-e2q53", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121207-095437157", "type": "article", "title": "Tunable phononic crystals based on cylindrical Hertzian contact", "author": [ { "family_name": "Li", "given_name": "Feng", "clpid": "Li-Feng" }, { "family_name": "Ngo", "given_name": "Duc", "clpid": "Ngo-Duc" }, { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate the tunability of phononic crystals consisting of arrays of cylindrical elements using theoretical, numerical, and experimental approaches. We show that when these systems are excited by a continuous dynamic signal under large static precompression, they support a characteristic band structure whose cutoff frequency can be controlled by changing the alignment angles or the static precompression. Furthermore, we report the formation of an additional pass band when there exists particles' eccentricity, which is caused by the coupling mechanism between longitudinal and shear modes.", "doi": "10.1063/1.4762832", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2012-10-22", "series_number": "17", "volume": "101", "issue": "17", "pages": "Art. No. 171903" }, { "id": "authors:f3nsy-e9206", "collection": "authors", "collection_id": "f3nsy-e9206", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-145741664", "type": "book_section", "title": "Nonlinear Periodic Phononic Structures and Granular Crystals", "book_title": "Acoustic Metamaterials and Phononic Crystals", "author": [ { "family_name": "Theocharis", "given_name": "G.", "clpid": "Theocharis-G" }, { "family_name": "Boechler", "given_name": "N.", "clpid": "Boechler-N" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "contributor": [ { "family_name": "Deymier", "given_name": "Pierre A.", "clpid": "Deymier-P-A" } ], "abstract": "This chapter describes the dynamic behavior of nonlinear periodic phononic structures, along with how such structures can be utilized to affect the propagation of mechanical waves. Granular crystals are one type of nonlinear periodic phononic structure and are the focus of this chapter. The chapter begins with a brief history of nonlinear lattices and an introduction to granular crystals. This is followed by a summary of past and recent work on one-dimensional (1D) and two-dimensional (2D) granular crystals, which is categorized according to the crystals' periodicity and dynamical regime. The chapter is concluded with a commentary by the authors, which discusses several possible future directions relating to granular crystals and other nonlinear periodic phononic structures. Throughout this chapter, a richness of nonlinear dynamic effects that occur in granular crystals is revealed, including a plethora of phenomena with no linear analog such as solitary waves, discrete breathers, tunable frequency band gaps, bifurcations, and chaos. Furthermore, in addition to the description of fundamental nonlinear phenomena, the authors describe how such phenomena can enable novel engineering devices and be applied to other nonlinear periodic systems.", "doi": "10.1007/978-3-642-31232-8_7", "isbn": "978-3-642-31231-1", "publisher": "Springer", "place_of_publication": "New York, NY", "publication_date": "2012-10-19", "pages": "217-251" }, { "id": "authors:hxkcw-gtd85", "collection": "authors", "collection_id": "hxkcw-gtd85", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121029-132545295", "type": "article", "title": "In situ synthesis of metal oxides in carbon nanotube arrays and mechanical properties of the resulting structures", "author": [ { "family_name": "Raney", "given_name": "Jordan R.", "clpid": "Raney-J-R" }, { "family_name": "Zhang", "given_name": "Hong-Li", "clpid": "Zhang-Hong-Li" }, { "family_name": "Morse", "given_name": "Daniel E.", "clpid": "Morse-D-E" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In the past, aligned arrays of carbon nanotubes (CNTs) have been observed to exhibit a foam-like dissipative response in compression, garnering attention for possible mechanical applications. Nanoparticles have previously been integrated with graphitic materials for electrochemical applications. Here, we synthesize nanoparticles of SnO_2 and MnO_2 in the interstices of aligned arrays of CNTs without altering the ordered structure of the arrays, and we characterize their mechanical response. We report that CNT arrays with embedded particles present superior energy dissipation relative to unmodified CNT arrays. In addition, energy dissipation, strain recovery, and structural failure (observed after repeated loading) depend on particle type (SnO_2 versus MnO_2).", "doi": "10.1016/j.carbon.2012.05.021", "issn": "0008-6223", "publisher": "Elsevier", "publication": "Carbon", "publication_date": "2012-10", "series_number": "12", "volume": "50", "issue": "12", "pages": "4432-4440" }, { "id": "authors:nbbyh-h4r40", "collection": "authors", "collection_id": "nbbyh-h4r40", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121130-093256159", "type": "article", "title": "Site-Specific Quantification of Bone Quality Using Highly Nonlinear Solitary Waves", "author": [ { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Sangiorgio", "given_name": "Sophia N.", "clpid": "Sangiorgio-S-N" }, { "family_name": "Borkowski", "given_name": "Sean L.", "clpid": "Borkowski-S-L" }, { "family_name": "Silvestro", "given_name": "Claudio", "clpid": "Silvestro-C" }, { "family_name": "De Nardo", "given_name": "Luigi", "orcid": "0000-0002-7492-6012", "clpid": "De-Nardo-L" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Ebramzadeh", "given_name": "Edward", "clpid": "Ebramzadeh-E" } ], "abstract": "Osteoporosis is a well recognized problem affecting millions of individuals worldwide. The ability to diagnose problems in an effective, efficient, and affordable manner and identify individuals at risk is essential. Site-specific assessment of bone mechanical properties is necessary, not only in the process of fracture risk assessment, but may also be desirable for other applications, such as making intraoperative decisions during spine and joint replacement surgeries. The present study evaluates the use of a one-dimensional granular crystal sensor to measure the elastic properties of bone at selected locations via direct mechanical contact. The granular crystal is composed of a tightly packed chain of particles that interact according to the Hertzian contact law. Such chains represent one of the simplest systems to generate and propagate highly nonlinear acoustic signals in the form of compact solitary waves. First, we investigated the sensitivity of the sensor to known variations in bone density using a synthetic cancellous bone substitute, representing clinical bone quality ranging from healthy to osteoporotic. Once the relationship between the signal response and known bone properties was established, the sensor was used to assess the bone quality of ten human cadaveric specimens. The efficacy and accuracy of the sensor was then investigated by comparing the sensor measurements with the bone mineral density (BMD) obtained using dual-energy x-ray absorptiometry (DEXA). The results indicate that the proposed technique is capable of detecting differences in bone quality. The ability to measure site-specific properties without exposure to radiation has the potential to be further developed for clinical applications.", "doi": "10.1115/1.4007364", "issn": "0148-0731", "publisher": "American Society of Mechanical Engineers", "publication": "Journal of Biomechanical Engineering", "publication_date": "2012-10", "series_number": "10", "volume": "134", "issue": "10", "pages": "Art. No. 101001" }, { "id": "authors:hcsrb-xcd05", "collection": "authors", "collection_id": "hcsrb-xcd05", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121115-103054395", "type": "article", "title": "Continuum limits of bistable spring models of carbon nanotube arrays accounting for material damage", "author": [ { "family_name": "Blesgen", "given_name": "T.", "clpid": "Blesgen-T" }, { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Raney", "given_name": "J. R.", "clpid": "Raney-J-R" }, { "family_name": "Amendola", "given_name": "A.", "orcid": "0000-0002-2562-881X", "clpid": "Amendola-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Using chains of bistable springs, a model is derived to investigate the plastic behavior of carbon nanotube arrays with damage. We study the preconditioning effect due to the loading history by computing analytically the stress\u2013strain pattern corresponding to a fatigue-type damage of the structure. We identify the convergence of the discrete response to the limiting case of infinitely many springs, both analytically in the framework of Gamma-convergence, as well as numerically.", "doi": "10.1016/j.mechrescom.2012.07.006", "issn": "0093-6413", "publisher": "Elsevier", "publication": "Mechanics Research Communications", "publication_date": "2012-10", "volume": "45", "pages": "58-63" }, { "id": "authors:radwy-0r148", "collection": "authors", "collection_id": "radwy-0r148", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121026-101824782", "type": "article", "title": "Effects of weak disorder on stress-wave anisotropy in centered square nonlinear granular crystals", "author": [ { "family_name": "Leonard", "given_name": "A.", "clpid": "Leonard-Andrea-B" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Awasthi", "given_name": "A.", "clpid": "Awasthi-A" }, { "family_name": "Geubelle", "given_name": "P.", "clpid": "Geubelle-P" } ], "abstract": "The present study describes wave propagation characteristics in a weakly disordered two-dimensional granular media composed of a square array of spheres accommodating interstitial cylindrical intruders. Previous investigations, performed experimentally as well as numerically, emphasized that wave-front shapes in similar systems are tunable via choice of material combinations. Here, we investigate the effects of statistical variation in the particle diameters and compare the effects of the resulting disorder in experiments and numerical simulations, finding good agreement.", "doi": "10.1103/PhysRevE.86.031305", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2012-09-21", "series_number": "3", "volume": "86", "issue": "3", "pages": "Art. No. 031305" }, { "id": "authors:5qk0g-jn531", "collection": "authors", "collection_id": "5qk0g-jn531", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200518-122714162", "type": "book_section", "title": "Experimental Testing of Micro-Particles Collision", "book_title": "Dynamic Behavior of Materials", "author": [ { "family_name": "Lin", "given_name": "Wei-Hsun", "clpid": "Lin-Wei-Hsun" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "contributor": [ { "family_name": "Chalivendra", "given_name": "Vijaya", "clpid": "Chalivendra-V-B" }, { "family_name": "Song", "given_name": "Bo", "clpid": "Song-Bo" }, { "family_name": "Casem", "given_name": "Daniel", "clpid": "Casem-D" } ], "abstract": "We performed experiments on the collisions of micrometer scale (200\u2013300 \u03bcm) stainless steel (316 and 440 C) particles and studied the interaction properties and the coefficient of restitution. We used a novel experimental apparatus to enable non-contact measurements based on laser excitations/detection and high-speed photography. The colliding particles were aligned in v-shaped grooves on a silicon wafer, fabricated using anisotropic etching techniques. We used high-power lasers to excite one of the particles (striker), and to control the impact velocity with high repeatability. The motion of the striker particle was triggered by partial laser ablation of its surface. The displacements of the particles involved in the collision were recorded with a high-speed camera mounted on an optical microscope. The particle velocities were obtained from the recorded images using digital image correlation. We calibrated the setup by tracking the dynamic excitation of single particles, and tested collisions between two particles. This study introduces a new experimental approach to understand the fundamental dynamic response of micro-particle collisions, and to test the limits of validity of the Hertzian interaction law.", "doi": "10.1007/978-1-4614-4238-7_61", "isbn": "978-1-4614-4237-0", "publisher": "Springer", "place_of_publication": "New York, NY", "publication_date": "2012-09-13", "pages": "475-480" }, { "id": "authors:eggg1-r7195", "collection": "authors", "collection_id": "eggg1-r7195", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200519-135320125", "type": "book_section", "title": "Dynamics of Multilayered Structures of VACNTs with Metallic Inter-layers", "book_title": "Dynamic Behavior of Materials", "author": [ { "family_name": "Thevamaran", "given_name": "Ramathasan", "orcid": "0000-0001-5058-6167", "clpid": "Thevamaran-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "contributor": [ { "family_name": "Chalivendra", "given_name": "Vijaya", "clpid": "Chalivendra-V-B" }, { "family_name": "Song", "given_name": "Bo", "clpid": "Song-Bo" }, { "family_name": "Casem", "given_name": "Daniel", "clpid": "Casem-D" } ], "abstract": "We study the dynamic behavior of periodic multilayered structures composed of compliant freestanding vertically aligned carbon nanotube (VACNT) arrays alternating with rigid metallic inter-layers, subjected to small transient excitations. The presence of intrinsically nonlinear effects in VACNTs arrays enable us to create materials and structures with tunable properties in which, for example, the stiffness can be tuned over a large range. As a result, the dynamic stress propagation properties in these materials can be tailored to specific applications.", "doi": "10.1007/978-1-4614-4238-7_59", "isbn": "978-1-4614-4237-0", "publisher": "Springer", "place_of_publication": "New York, NY", "publication_date": "2012-09-13", "pages": "463-465" }, { "id": "authors:2asmv-mg690", "collection": "authors", "collection_id": "2asmv-mg690", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120705-111154235", "type": "article", "title": "Interaction of highly nonlinear solitary waves with thin plates", "author": [ { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Khatri", "given_name": "Devvrath", "clpid": "Khatri-D" }, { "family_name": "Anzel", "given_name": "Paul", "clpid": "Anzel-P" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate the reflection of highly nonlinear solitary waves in one-dimensional granular crystals interacting with large plates. We observe significant changes in the reflected waves' properties in terms of wave amplitude and time of flight in association with the intrinsic inelasticity of large plates, which are governed by the plate thickness and the size of the granular constituents. We also study the effects of fixed plate boundaries in the formation of reflected waves, and find the existence of a critical distance, within which the interaction between the granular chain and plate is strongly modified. We explain the effects of intrinsic inelasticity and of boundaries in the large plates by using plate theory and the contact mechanics between a plate and a spherical striker. We find that experimental results are in excellent agreement with the analytical predictions and numerical simulations based on the combined discrete element and spectral element models. The findings in this study can be useful for the nondestructive evaluation of plate structures using granular crystals, which can improve the resolution of in-situ, portable measurement instruments leveraging high acoustic energy and sensitivity of solitary waves.", "doi": "10.1016/j.ijsolstr.2012.02.013", "issn": "0020-7683", "publisher": "Elsevier", "publication": "International Journal of Solids and Structures", "publication_date": "2012-06-15", "series_number": "13", "volume": "49", "issue": "13", "pages": "1463-1471" }, { "id": "authors:qhnyg-6x233", "collection": "authors", "collection_id": "qhnyg-6x233", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120522-112410467", "type": "article", "title": "Solitary waves on tensegrity lattices", "author": [ { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Senatore", "given_name": "L.", "clpid": "Senatore-L" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the dynamics of lattices formed by masses connected through tensegrity prisms. By employing analytic and numerical arguments, we show that such structures support two limit dynamic regimes controlled by the prisms' properties: (i) in the low-energy (sonic) regime the system supports the formation and propagation of solitary waves which exhibit sech^2 shape and (ii) in the high-energy (ultrasonic) regime the system supports atomic-scale localization. Such peculiar features found in periodic arrays of tensegrity structures suggest their use for the creation of new composite materials (here called \"tensegrity materials\") of potential interest for applications in impact absorption, energy localization and in new acoustic devices.", "doi": "10.1016/j.jmps.2012.02.007", "issn": "0022-5096", "publisher": "Elsevier", "publication": "Journal of the Mechanics and Physics of Solids", "publication_date": "2012-06", "series_number": "6", "volume": "60", "issue": "6", "pages": "1137-1144" }, { "id": "authors:e9ggh-hgx92", "collection": "authors", "collection_id": "e9ggh-hgx92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120620-083550560", "type": "article", "title": "Stress Wave Anisotropy in Centered Square Highly Nonlinear Granular Systems", "author": [ { "family_name": "Leonard", "given_name": "A.", "clpid": "Leonard-Andrea-B" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Highly ordered, close packed granular systems present a nonlinear dynamic behavior stemming from the Hertzian contact interaction between particles. We investigated the propagation of elastic stress waves in an uncompressed, centered square array of spherical and cylindrical particles. We show, via experiments and numerical simulations, that systematic variations of the mass and stiffness ratios of the spherical and cylindrical particles lead to large variations in the characteristics of the propagating stress wave fronts traveling through the system. The ability to control the stress wave front properties in these granular systems may allow for the development of new wave-tailoring materials including systems capable of redirecting impact energy.", "doi": "10.1103/PhysRevLett.108.214301", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2012-05-21", "series_number": "21", "volume": "108", "issue": "21", "pages": "Art. No. 214301" }, { "id": "authors:jz1p3-ara37", "collection": "authors", "collection_id": "jz1p3-ara37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190826-092412704", "type": "book_section", "title": "Dynamic Behavior of Periodic Structures Consisting of Vertically Aligned Carbon Nanotubes and Rigid Interlayers", "book_title": "53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference", "author": [ { "family_name": "Yamamoto", "given_name": "Namiko", "clpid": "Yamamoto-Namiko" }, { "family_name": "Thevamaran", "given_name": "Ramathasan", "orcid": "0000-0001-5058-6167", "clpid": "Thevamaran-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We assembled novel periodic structures by alternating aligned carbon nanotube (CNT) discs and polycarbonate cylindrical particles for stress damping applications. CNTs are known to present a nonlinear, hysteretic mechanical behavior in compression with the ability to recover from large strains. Furthermore, CNTs are generally more lightweight and thermally stable than currently existing viscoelastic polymers. We test the dynamic response of these CNT/polycarbonate multilayer systems excited by an impact. The response of these systems is found to be highly nonlinear and tunable by variation of the static precompression applied. We studied the wave propagation properties and dissipation in these systems and found that the presence of CNTs improves the energy damping properties of the system when compared with the one observed in polycarbonate particles alone. Such improvement was higher with smaller precompression loads. More detailed studies are required to understand the origin of the observed dynamic behavior.", "doi": "10.2514/6.2012-1389", "isbn": "9781600869372", "publisher": "American Institute of Aeronautics and Astronautics", "place_of_publication": "Reston, VA", "publication_date": "2012-04-23", "pages": "Art. No. 2012-1389" }, { "id": "authors:2kxqr-d2z52", "collection": "authors", "collection_id": "2kxqr-d2z52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120608-092706429", "type": "article", "title": "Nonlinear viscoelasticity of freestanding and polymer-anchored vertically aligned carbon nanotube foams", "author": [ { "family_name": "Lattanzi", "given_name": "Ludovica", "clpid": "Lattanza-L" }, { "family_name": "Raney", "given_name": "Jordan R.", "clpid": "Raney-J-R" }, { "family_name": "De Nardo", "given_name": "Luigi", "orcid": "0000-0002-7492-6012", "clpid": "De-Nardo-L" }, { "family_name": "Misra", "given_name": "Abha", "clpid": "Misra-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Vertical arrays of carbon nanotubes (VACNTs) show unique mechanical behavior in compression, with a highly nonlinear response similar to that of open cell foams and the ability to recover large deformations. Here, we study the viscoelastic response of both freestanding VACNT arrays and sandwich structures composed of a VACNT array partially embedded between two layers of poly(dimethylsiloxane) (PDMS) and bucky paper. The VACNTs tested are \u223c2 mm thick foams grown via an injection chemical vapor deposition method. Both freestanding and sandwich structures exhibit a time-dependent behavior under compression. A power-law function of time is used to describe the main features observed in creep and stress-relaxation tests. The power-law exponents show nonlinear viscoelastic behavior in which the rate of creep is dependent upon the stress level and the rate of stress relaxation is dependent upon the strain level. The results show a marginal effect of the thin PDMS/bucky paper layers on the viscoelastic responses. At high strain levels (\u025b = 0.8), the peak stress for the anchored CNTs reaches \u223c45 MPa, whereas it is only \u223c15\u2009MPa for freestanding CNTs, suggesting a large effect of PDMS on the structural response of the sandwich structures.", "doi": "10.1063/1.3699184", "issn": "0021-8979", "publisher": "American Institute of Physics", "publication": "Journal of Applied Physics", "publication_date": "2012-04-01", "series_number": "7", "volume": "111", "issue": "7", "pages": "Art. No. 074314" }, { "id": "authors:e3zba-v9y22", "collection": "authors", "collection_id": "e3zba-v9y22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120606-154003951", "type": "book_section", "title": "Investigation of co-travelling solitary wave collisions in a granular chain", "book_title": "Smart sensor phenomena, technology, networks, and systems", "author": [ { "family_name": "Anzel", "given_name": "Paul", "clpid": "Anzel-P" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "contributor": [ { "family_name": "Matikas", "given_name": "Theodore E.", "clpid": "Matikas-T-E" }, { "family_name": "Peters", "given_name": "Kara J.", "clpid": "Peters-K-J" }, { "family_name": "Ecke", "given_name": "Wolfgang", "clpid": "Ecke-W" } ], "abstract": "We present investigations into the collision of co-travelling solitary waves in a granular chain. Impulses are injected into the system by means of a piezo stack and the results are compared to a numerical model of discrete masses connected by non-linear springs. Similar to other solitary wave-carrying systems, a phase shift in both interacting solitary waves is observed due to their collision. Additionally, the formation of small secondary waves is observed in both numerical and experimental results. Insight into solitary wave interactions will be important for high-frequency excitation of a granular crystal, which may allow for improved Non-Destructive Evaluation (NDE) and Structural Health Monitoring (SHM) methods.", "doi": "10.1117/12.917474", "isbn": "978-0-8194-9003-2", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2012-03-30", "pages": "Art. No. 83460G" }, { "id": "authors:9r74x-gt384", "collection": "authors", "collection_id": "9r74x-gt384", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120406-101736422", "type": "article", "title": "Highly nonlinear solitary wave propagation in Y-shaped granular crystals with variable branch angles", "author": [ { "family_name": "Ngo", "given_name": "D.", "clpid": "Ngo-Duc" }, { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the propagation of highly nonlinear waves in a branched (Y-shaped) granular crystal composed of chains of spherical particles of different materials, arranged at variable branch angles. We experimentally test the dynamic behavior of a solitary pulse, or of a train of solitary waves, crossing the Y-junction interface, and splitting between the two branches. We describe the dependence of the split pulses' speed and amplitude on the branch angles. Analytic predictions based on the quasiparticle model and numerical simulations based on Hertzian interactions between the particles are found to be in excellent agreement with the experimental data.", "doi": "10.1103/PhysRevE.85.036602", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2012-03-06", "series_number": "3", "volume": "85", "issue": "3", "pages": "Art. No. 036602" }, { "id": "authors:pvbxy-rtn46", "collection": "authors", "collection_id": "pvbxy-rtn46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120430-110648937", "type": "article", "title": "Amplitude-dependent attenuation of compressive waves in curved granular crystals constrained by elastic guides", "author": [ { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Dunatunga", "given_name": "Sachith", "clpid": "Dunatunga-S" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the wave propagation in a curved chain of spherical particles constrained by elastic guides under the axial impact of a falling mass. We characterize the force transmission properties of the chain by varying the striker's mass and the chain's curvature. Experimental tests demonstrate amplitude-dependent attenuation of compressive waves propagating through the curved chain. In particular, we observe that the curved systems present an improved transmission of small dynamic disturbances relative to that of strong excitations, resulting from the close interplay between the granular particles and the softer elastic medium. We also find that the transmission of the compressive waves through the chains is dependent on the initial curvature imposed to the system. Numerical simulations, based on an approach that combines discrete element and finite element methods, corroborate the experimental results. The findings suggest that hybrid structures composed of granular particles and linear elastic media can be employed as new passive acoustic filtering materials that selectively transmit or mitigate excitations in a desired range of pressure amplitudes.", "doi": "10.1007/s00707-011-0568-x", "issn": "0001-5970", "publisher": "Springer", "publication": "Acta Mechanica", "publication_date": "2012-03", "series_number": "3", "volume": "223", "issue": "3", "pages": "549-562" }, { "id": "authors:gbgyn-2ry31", "collection": "authors", "collection_id": "gbgyn-2ry31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120501-132603317", "type": "article", "title": "Defect modes in one-dimensional granular crystals", "author": [ { "family_name": "Man", "given_name": "Y.", "clpid": "Man-Y" }, { "family_name": "Boechler", "given_name": "N.", "clpid": "Boechler-N" }, { "family_name": "Theocharis", "given_name": "G.", "clpid": "Theocharis-G" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the vibrational spectra of one-dimensional statically compressed granular crystals (arrays of elastic particles in contact) containing light-mass defects. We focus on the prototypical settings of one or two spherical defects (particles of smaller radii) interspersed in a chain of larger uniform spherical particles. We present a systematic measurement, using continuous noise, of the near-linear frequency spectrum within the spatial vicinity of the defect(s). Using this technique, we identify the frequencies of the localized defect modes as a function of the defect size and the position of the defects relative to each other. We also compare the experimentally determined frequencies with those obtained by numerical eigenanalysis and by analytical expressions based on few-site considerations. These approximate analytical expressions, based on normal-mode analysis, are found to be in excellent agreement with numerics for a wide range of mass ratios. We also observe that the experimentally measured frequencies of the localized defect modes are uniformly upshifted, compared to the numerically and theoretically predicted values.", "doi": "10.1103/PhysRevE.85.037601", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2012-03", "series_number": "3", "volume": "85", "issue": "3", "pages": "Art. No. 037601" }, { "id": "authors:3fmv3-aca71", "collection": "authors", "collection_id": "3fmv3-aca71", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120213-105857273", "type": "article", "title": "Highly nonlinear solitary waves in chains of cylindrical particles", "author": [ { "family_name": "Khatri", "given_name": "Devvrath", "clpid": "Khatri-D" }, { "family_name": "Ngo", "given_name": "Duc", "clpid": "Ngo-Duc" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the dynamic response of uniform granular\nchains composed of short cylindrical particles excited by\nan impulse. The particles in the chains are arranged with their\naxes orthogonal to the chain's axis, and the particles maintain\na constant relative orientation angle. We study the formation\nand propagation of solitary waves in the chains varying the\norientation angle (\u03b1) between particles, and show tunability\nof the stress transfer as a function of \u03b1. We use the general\nHertzian contact theory to model the interaction between\nparticles. We compare experimental findings with theoretical\npredictions based on the long wavelength approximation,\nand with numerical predictions based on a one-dimensional\ndiscrete particle model, and on a three-dimensional finite element\napproach, finding good agreement.", "doi": "10.1007/s10035-011-0297-9", "issn": "1434-7636", "publisher": "Springer", "publication": "Granular Matter", "publication_date": "2012-02", "series_number": "1", "volume": "14", "issue": "1", "pages": "63-69" }, { "id": "authors:54f95-v7548", "collection": "authors", "collection_id": "54f95-v7548", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120124-144405246", "type": "article", "title": "Nondestructive evaluation of orthopaedic implant stability in THA using highly nonlinear solitary waves", "author": [ { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Silvestro", "given_name": "Claudio", "clpid": "Silvestro-C" }, { "family_name": "Sangiorgio", "given_name": "Sophia N.", "clpid": "Sangiorgio-S-N" }, { "family_name": "Borkowski", "given_name": "Sean L.", "clpid": "Borkowski-S-L" }, { "family_name": "Ebramzadeh", "given_name": "Edward", "clpid": "Ebramzadeh-E" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We propose a new biomedical sensing technique based on highly nonlinear solitary waves to assess orthopaedic implant stability in a nondestructive and efficient manner. We assemble a granular crystal actuator consisting of a one-dimensional tightly packed array of spherical particles, to generate acoustic solitary waves. Via direct contact with the specimen, we inject acoustic solitary waves into a biomedical prosthesis, and we nondestructively evaluate the mechanical integrity of the bone\u2013prosthesis interface, studying the properties of the waves reflected from the contact zone between the granular crystal and the implant. The granular crystal contains a piezoelectric sensor to measure the travelling solitary waves, which allows it to function also as a sensor. We perform a feasibility study using total hip arthroplasty (THA) samples made of metallic stems implanted in artificial composite femurs using polymethylmethacrylate for fixation. We first evaluate the sensitivity of the proposed granular crystal sensor to various levels of prosthesis insertion into the composite femur. Then, we impose a sequence of harsh mechanical loading on the THA samples to degrade the mechanical integrity at the stem\u2013cement interfaces, using a femoral load simulator that simulates aggressive, accelerated physiological loading. We investigate the implant stability via the granular crystal sensor\u2013actuator during testing. Preliminary results suggest that the reflected waves respond sensitively to the degree of implant fixation. In particular, the granular crystal sensor\u2013actuator successfully detects implant loosening at the stem\u2013cement interface following violent cyclic loading. This study suggests that the granular crystal sensor and actuator has the potential to detect metal\u2013cement defects in a nondestructive manner for orthopaedic applications.", "doi": "10.1088/0964-1726/21/1/012002", "issn": "0964-1726", "publisher": "IOP", "publication": "Smart Materials and Structures", "publication_date": "2012-01", "series_number": "1", "volume": "21", "issue": "1", "pages": "Art. No. 012002" }, { "id": "authors:j0rz4-a2y47", "collection": "authors", "collection_id": "j0rz4-a2y47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111128-085742465", "type": "article", "title": "Mesoscopic approach to granular crystal dynamics", "author": [ { "family_name": "Gonzalez", "given_name": "Marcial", "clpid": "Gonzalez-M" }, { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Ortiz", "given_name": "Michael", "orcid": "0000-0001-5877-4824", "clpid": "Ortiz-M" } ], "abstract": "We present a mesoscopic approach to granular crystal dynamics, which comprises a three-dimensional finite-element model and a one-dimensional regularized contact model. The approach investigates the role of vibrational-energy trapping effects in the dynamic behavior of one-dimensional chains of particles in contact (i.e., granular crystals), under small to moderate impact velocities. The only inputs of the models are the geometry and the elastic material properties of the individual particles that form the system. We present detailed verification results and validate the model comparing its predictions with experimental data. This approach provides a physically sound, first-principle description of dissipative losses in granular systems.", "doi": "10.1103/PhysRevE.85.016604", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2012-01", "series_number": "1", "volume": "85", "issue": "1", "pages": "Art. No. 016604" }, { "id": "authors:1t4pd-ecv12", "collection": "authors", "collection_id": "1t4pd-ecv12", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130814-105941438", "type": "book_section", "title": "Angular Dependence of Highly Nonlinear Pulse Splitting in a Two Dimensional Granular Network", "book_title": "2010 Proceedings of the ASME International Mechanical Engineering Congress and Exposition", "author": [ { "family_name": "Ngo", "given_name": "D.", "clpid": "Ngo-Duc" }, { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate experimentally and numerically the\npropagation of highly nonlinear signals in a branched two-dimensional\ngranular system composed by chains of uniform\nspherical beads. The system consists of a Y-shaped guide with\nvarious branch angles in which stainless steel spheres are\narranged. We study the dynamic behavior of a solitary pulse\ncrossing the bifurcated interface, and splitting between the two\nbranches. We report for the first time the dependence of the\nsplit pulses' speed on the branch angles. Numerical simulations\nbased on Hertzian interaction between the particles are found in\nagreement with the experimental data.", "doi": "10.1115/IMECE2010-39599", "isbn": "978-0-7918-4446-5", "publisher": "American Society of Mechanical Engineers", "place_of_publication": "New York, NY", "publication_date": "2012", "pages": "361-366" }, { "id": "authors:q2kc9-wdp43", "collection": "authors", "collection_id": "q2kc9-wdp43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111024-113245117", "type": "article", "title": "Effect of density variation and non-covalent functionalization on the compressive behavior of carbon nanotube arrays", "author": [ { "family_name": "Misra", "given_name": "A.", "clpid": "Misra-A" }, { "family_name": "Raney", "given_name": "J. R.", "clpid": "Raney-J-R" }, { "family_name": "Craig", "given_name": "A. E.", "clpid": "Craig-A-E" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Arrays of aligned carbon nanotubes (CNTs) have been proposed for different applications, including electrochemical energy storage and shock-absorbing materials. Understanding their mechanical response, in relation to their structural characteristics, is important for tailoring the synthesis method to the different operational conditions of the material. In this paper, we grow vertically aligned CNT arrays using a thermal chemical vapor deposition system, and we study the effects of precursor flow on the structural and mechanical properties of the CNT arrays. We show that the CNT growth process is inhomogeneous along the direction of the precursor flow, resulting in varying bulk density at different points on the growth substrate. We also study the effects of non-covalent functionalization of the CNTs after growth, using surfactant and nanoparticles, to vary the effective bulk density and structural arrangement of the arrays. We find that the stiffness and peak stress of the materials increase approximately linearly with increasing bulk density.", "doi": "10.1088/0957-4484/22/42/425705", "issn": "0957-4484", "publisher": "IOP", "publication": "Nanotechnology", "publication_date": "2011-10-21", "series_number": "42", "volume": "22", "issue": "42", "pages": "Art. No. 425705" }, { "id": "authors:6w38v-fmz39", "collection": "authors", "collection_id": "6w38v-fmz39", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111122-112215891", "type": "article", "title": "Synthesis and Characterization of Carbon Nanotube\u2013Polymer Multilayer Structures", "author": [ { "family_name": "Misra", "given_name": "Abha", "clpid": "Misra-A" }, { "family_name": "Raney", "given_name": "Jordan R.", "clpid": "Raney-J-R" }, { "family_name": "De Nardo", "given_name": "Luigi", "orcid": "0000-0002-7492-6012", "clpid": "De-Nardo-L" }, { "family_name": "Craig", "given_name": "Anna E.", "clpid": "Craig-A-E" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We develop lightweight, multilayer materials composed of alternating layers of poly dimethyl siloxane (PDMS) polymer and vertically aligned carbon nanotube (CNT) arrays, and characterize their mechanical response in compression. The CNT arrays used in the assembly are synthesized with graded mechanical properties along their thickness, and their use enables the creation of multilayer structures with low density (0.12\u20130.28 g/cm^3). We test the mechanical response of structures composed of different numbers of CNT layers partially embedded in PDMS polymer, under quasi-static and dynamic loading. The resulting materials exhibit a hierarchical, fibrous structure with unique mechanical properties: They can sustain large compressive deformations (~0.8 strain) with a nearly complete recovery and present strain localization in selected sections of the materials. Energy absorption, as determined by the hysteresis observed in stress\u2013strain curves, is found to be at least 3 orders of magnitude larger than that of natural and synthetic cellular materials of comparable density. Conductive bucky paper is included within the polymer interlayers. This allows the measurement of resistance variation as a function of applied stress, showing strong correlation with the observed strain localization in compression.", "doi": "10.1021/nn202262j", "issn": "1936-0851", "publisher": "American Chemical Society", "publication": "ACS Nano", "publication_date": "2011-10", "series_number": "10", "volume": "5", "issue": "10", "pages": "7713-7721" }, { "id": "authors:tjhpb-yyw89", "collection": "authors", "collection_id": "tjhpb-yyw89", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110921-094930189", "type": "article", "title": "Modeling and in situ identification of material parameters for layered structures based on carbon nanotube arrays", "author": [ { "family_name": "Raney", "given_name": "J. R.", "clpid": "Raney-J-R" }, { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Amendola", "given_name": "A.", "orcid": "0000-0002-2562-881X", "clpid": "Amendola-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We test and model the mechanical response of a multilayer composite structure composed of alternating layers of aligned carbon nanotubes and copper foils under compression. We employ a bistable mass-spring model to capture the three-phase hysteretic response of the loading curve with excellent agreement with the experimental observations. An in situ identification procedure is proposed to quantify the material parameters corresponding to the mesoscopic scale of the structure. We refine the results using a genetic algorithm and compare the response of two different models based on three and four springs in series. The localization of deformation can be accurately captured by these simplified models, which hold promise for the design of novel materials with tailored deformation responses.", "doi": "10.1016/j.compstruct.2011.04.034", "issn": "0263-8223", "publisher": "Elsevier", "publication": "Composite Structures", "publication_date": "2011-10", "series_number": "11", "volume": "93", "issue": "11", "pages": "3013-3018" }, { "id": "authors:gpa8t-y6346", "collection": "authors", "collection_id": "gpa8t-y6346", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161003-123235426", "type": "book_section", "title": "Synthesis and Patterning Methods for Nanostructures Useful for Biological Applications", "book_title": "Nanotechnology for Biology and Medicine: At the Building Block Level", "author": [ { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Jin", "given_name": "Sungho", "clpid": "Jin-Sungho" } ], "contributor": [ { "family_name": "Silva", "given_name": "Gabriel A.", "clpid": "Silva-G-A" }, { "family_name": "Parpura", "given_name": "Vladimir", "clpid": "Parpura-V" } ], "abstract": "The importance and benefits of nanotechnology in biology and medicine are now well-recognized by scientists, technologists, as well as various governmental and private research funding agencies. The basis that enables the application of nanotechnology is the availability of nanostructured materials. Therefore, it is essential to provide an insight on the state-of-the-art methods to manufacture various nanostructures.", "doi": "10.1007/978-0-387-31296-5_2", "isbn": "978-0-387-31282-8", "publisher": "Springer", "place_of_publication": "New York, NY", "publication_date": "2011-09-05", "pages": "27-44" }, { "id": "authors:79fgm-zyy88", "collection": "authors", "collection_id": "79fgm-zyy88", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110803-103914144", "type": "article", "title": "Tailoring the microstructure and mechanical properties of\n arrays of aligned multiwall carbon nanotubes by utilizing\n different hydrogen concentrations during synthesis", "author": [ { "family_name": "Raney", "given_name": "Jordan R.", "clpid": "Raney-J-R" }, { "family_name": "Misra", "given_name": "Abha", "clpid": "Misra-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We synthesize vertically aligned arrays of carbon nanotubes (CNTs) in a chemical vapor deposition system with floating catalyst, using different concentrations of hydrogen in the gas feedstock. We report the effect of different hydrogen concentrations on the microstructure and mechanical properties of the resulting material. We show that a lower hydrogen concentration during synthesis results in the growth of stiffer CNT arrays with higher average bulk density. A lower hydrogen concentration also leads to the synthesis of CNT arrays that can reach higher peak stress at maximum compressive strain, and dissipate a larger amount of energy during compression. The individual CNTs in the arrays synthesized with a lower hydrogen concentration have, on average, larger outer diameters (associated with the growth of CNTs with a larger number of walls), but present a less uniform diameter distribution. The overall heights of the arrays and their strain recovery after compression have been found to be independent of the hydrogen concentration during growth.", "doi": "10.1016/j.carbon.2011.04.066", "issn": "0008-6223", "publisher": "Elsevier", "publication": "Carbon", "publication_date": "2011-09", "series_number": "11", "volume": "49", "issue": "11", "pages": "3631-3638" }, { "id": "authors:577p2-q7h16", "collection": "authors", "collection_id": "577p2-q7h16", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110912-071646806", "type": "article", "title": "Bifurcation-based acoustic switching and rectification", "author": [ { "family_name": "Boechler", "given_name": "N.", "clpid": "Boechler-N" }, { "family_name": "Theocharis", "given_name": "G.", "clpid": "Theocharis-G" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Switches and rectification devices are fundamental componentsused for controlling the flow of energy in numerous applications. Thermal and acoustic rectifiers have been proposed for use in biomedical ultrasound applications thermal computers energy-saving and-harvesting materials and direction-dependent insulating materials. In all these systems the transition between transmission states is smooth with increasing signal amplitudes. This limits their effectiveness as switching and logic devices, and reduces their sensitivity to external conditions as sensors. Here we overcome these limitations by demonstrating a new mechanism for tunable rectification that uses bifurcations and chaos. This mechanism has a sharp transition between states, which can lead to phononic switching and sensing. We present an experimental demonstration of this mechanism, applied in a mechanical energy rectifier operating at variable sonic frequencies. The rectifier is a granular crystal, composed of a statically compressed one-dimensional array of particles in contact, containing a light mass defect near a boundary. As a result of the defect, vibrations at selected frequencies cause bifurcations and a subsequent jump to quasiperiodic and chaotic states with broadband frequency content. We use this combination of frequency filtering and asymmetrically excited bifurcations to obtain rectification ratios greater than 10^4. We envisage this mechanism to enable the design of advanced photonic, thermal and acoustic materials and devices.", "doi": "10.1038/NMAT3072", "issn": "1476-1122", "publisher": "Nature Publishing Group", "publication": "Nature Materials", "publication_date": "2011-09", "series_number": "9", "volume": "10", "issue": "9", "pages": "665-668" }, { "id": "authors:g0h5w-d1d06", "collection": "authors", "collection_id": "g0h5w-d1d06", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110909-100346550", "type": "article", "title": "Highly nonlinear solitary waves in chains of ellipsoidal particles", "author": [ { "family_name": "Ngo", "given_name": "Duc", "clpid": "Ngo-Duc" }, { "family_name": "Khatri", "given_name": "Devvrath", "clpid": "Khatri-D" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the dynamic response of a one-dimensional chain of ellipsoidal particles excited by a single compressive impulse. We detail the Hertzian contact theory describing the interaction between two ellipsoidal particles under compression, and use it to model the dynamic response of the system. We observe the formation of highly nonlinear solitary waves in the chain, and we also study their propagation properties. We measure experimentally the traveling pulse amplitude (force), the solitary wave speed, and the solitary wave width. We compare these results with theoretical predictions in the long wavelength approximation, and with numerical results obtained with a discrete particle model and with finite element simulations. We also study the propagation of highly nonlinear solitary waves in the chain with particles arranged in different configurations to show the effects of the particle's geometry on the wave propagation characteristics and dissipation. We find very good agreement between experiment, theory, and simulations for all the ranges of impact velocity and particle arrangements investigated.", "doi": "10.1103/PhysRevE.84.026610", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2011-08-16", "series_number": "2", "volume": "84", "issue": "2", "pages": "Art. No. 026610" }, { "id": "authors:f9nyf-0gx27", "collection": "authors", "collection_id": "f9nyf-0gx27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110822-093153993", "type": "article", "title": "Laser-based excitation of nonlinear solitary waves in a chain of particles", "author": [ { "family_name": "Ni", "given_name": "Xianglei", "clpid": "Ni-Xianglei" }, { "family_name": "Rizzo", "given_name": "Piervincenzo", "clpid": "Rizzo-P" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Highly nonlinear solitary waves (HNSWs) are stress waves that can form and travel in highly nonlinear\nsystems. They are characterized by a constant spatial wavelength and by a tunable propagation speed, dependent\non the wave amplitude. Conventionally, HNSW's are generated in one-dimensional chains of spherical particles\nby means of a mechanical impact. In this paper, we demonstrate that short-duration laser pulses can be used\nto generate HNSW's, and we characterize their propagating properties in terms of shape, speed, and duration.\nWe compare the waves' characteristics with theoretical predictions, finding excellent agreement. In addition a\nsimplified formulation is given to estimate the dynamic contact force generated by laser pulses onto the chain.", "doi": "10.1103/PhysRevE.84.026601", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2011-08-02", "series_number": "2", "volume": "84", "issue": "2", "pages": "Art. No. 026601" }, { "id": "authors:sgd8n-3fz37", "collection": "authors", "collection_id": "sgd8n-3fz37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110706-112940606", "type": "article", "title": "Nonlinear repulsive force between two solids with axial symmetry", "author": [ { "family_name": "Sun", "given_name": "Diankang", "clpid": "Sun-Diankang" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Sen", "given_name": "Surajit", "clpid": "Sen-Surajit" } ], "abstract": "We modify the formulation of Hertz contact theory between two elastic half-solids with axial symmetry and show that these modifications to Hertz's original framework allow the development of force laws of the form F\u221dz^n, 10 to describe any aspect ratio in the two bodies, all being valid near the contact surface. We let the x-y plane be the contact surface with an averaged pressure across the same as opposed to a pressure profile that depends on the contact area of a nonconformal contact as originally used by Hertz. We let the z axis connect the centers of the masses and define z_(1,2) = x^(\u03b1)/R_(1,2)^(\u03b1-1) + y^(\u03b1)/(mR_(1,2))^(\u03b1-1), where z_(1,2)\u22650 refers to the compression of bodies 1, 2, \u03b1>1, m>0, x,y\u22650. The full cross section can be generated by appropriate reflections using the first quadrant part of the area. We show that the nonlinear repulsive force is F=az^n, where n\u22611+(1/\u03b1), and z\u2261z_1 + z_2 is the overlap and we present an expression for a=f(E,\u03c3,m,\u03b1,R_(1),R_(2)) with E and \u03c3 as Young's modulus and the Poisson ratio, respectively. For \u03b1=2,\u221e, to similar geometry-dependent constants, we recover Hertz's law and the linear law, describing the repulsion between compressed spheres and disks, respectively. The work provides a connection between the contact geometry and the nonlinear repulsive law via \u03b1 and m.", "doi": "10.1103/PhysRevE.83.066605", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2011-06-20", "series_number": "6", "volume": "83", "issue": "6", "pages": "Art. No. 066605" }, { "id": "authors:3g24f-22w24", "collection": "authors", "collection_id": "3g24f-22w24", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161005-071423962", "type": "book_section", "title": "Tailoring Stress Waves in 2-D Highly Nonlinear Granular Crystals: Simulations and Experiments", "author": [ { "family_name": "Leonard", "given_name": "Andrea", "clpid": "Leonard-Andrea-B" }, { "family_name": "Awasthi", "given_name": "Amnaya", "clpid": "Awasthi-A" }, { "family_name": "Geubelle", "given_name": "Philippe", "clpid": "Geubelle-P" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the propagation of elastic stress waves in two-dimensional highly nonlin-ear granular crystals composed of square packings of spheres with and without cylindrical intruders, via experiments and numerical simulations. By varying the intruder material, we show the ability to alter the propagating wave front characteristics. Experiments agree well with dis-crete particle simulations.", "publisher": "Caltech Library", "publication_date": "2011-06" }, { "id": "authors:vnf5a-te490", "collection": "authors", "collection_id": "vnf5a-te490", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-155606386", "type": "book_section", "title": "Experimental and Numerical Study of Wave Propagation in Granular Media", "book_title": "Dynamic Behavior of Materials", "author": [ { "family_name": "On", "given_name": "T.", "clpid": "On-T" }, { "family_name": "Smith", "given_name": "K. J.", "clpid": "Smith-K-J" }, { "family_name": "Geubelle", "given_name": "P. H.", "clpid": "Geubelle-P-H" }, { "family_name": "Lambros", "given_name": "J.", "clpid": "Lambros-J" }, { "family_name": "Spadoni", "given_name": "A.", "clpid": "Spadoni-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "contributor": [ { "family_name": "Proulx", "given_name": "Tom", "clpid": "Proulx-T" } ], "abstract": "One dimensional stress waves travelling in granular chains exhibit interesting characteristics such as filtering, tunability and wave mitigation because on the formation of solitary waves, and solitary wave trains, within them. An idealized one dimensional granular medium, consisting of a linear array of contacting spherical brass beads, was loaded dynamically in a modified split Hopkinson pressure bar, with loading pulses that span a variety of rates and profiles using pulse shaping techniques. Different chain lengths were studied to determine how solitary waves form in a varying length granular medium, as well as the speed of wave propagation. It is found that the wave speed propagates faster for longer chains of brass beads. The high loading rates of the Hopkinson bar also allowed us to investigate plastic dissipation effects in the granular chain when composed of different types of metals. To further our understanding of wave propagation in ductile ordered granular media, the experimental results are compared with companion numerical simulations based on a particle contact law that accounts for plastic dissipation. Knowing the behavior of a stress wave propagating through such materials can lead to arrangements that can produce desired stress wave mitigation characteristics as the waves travel through the granular chain.", "doi": "10.1007/978-1-4614-0216-9_13", "isbn": "978-1-4614-0215-2", "publisher": "Springer", "place_of_publication": "New York, NY", "publication_date": "2011-05-18", "pages": "95-98" }, { "id": "authors:h3wgb-zge56", "collection": "authors", "collection_id": "h3wgb-zge56", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110506-093926555", "type": "article", "title": "Nonlinear phononic crystals based on chains of disks alternating with toroidal structures", "author": [ { "family_name": "Spadoni", "given_name": "A.", "clpid": "Spadoni-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Hurst", "given_name": "W.", "clpid": "Hurst-W" }, { "family_name": "Brown", "given_name": "M.", "clpid": "Brown-M" } ], "abstract": "We study experimentally the acoustic response of a load-bearing, phononic crystal composed of alternating steel disks, and polytetrafluoroethylene o-rings under precompression. The crystal allows for axial, rocking, and shear-polarized wavemodes when excited by a broad-band signal applied off-axis. Finite element analysis is employed to determine the system's wave modes. The nonlinear interaction between disks and o-rings supports a dynamic response that is tunable with variations in static precompression, leading to controllable frequency shifts in a large band gap. A modal analysis reveals that four of the six principal wave modes are susceptible to external precompression while two modes are not.", "doi": "10.1063/1.3567753", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2011-04-18", "series_number": "16", "volume": "98", "issue": "16", "pages": "Art. No. 161901" }, { "id": "authors:n19f9-qa738", "collection": "authors", "collection_id": "n19f9-qa738", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110518-094202968", "type": "article", "title": "Tunable vibrational band gaps in one-dimensional diatomic granular crystals with three-particle unit cells", "author": [ { "family_name": "Boechler", "given_name": "N.", "clpid": "Boechler-N" }, { "family_name": "Yang", "given_name": "J.", "clpid": "Yang-Jinkyu" }, { "family_name": "Theocharis", "given_name": "G.", "clpid": "Theocharis-G" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate the tunable vibration filtering properties of statically compressed one-dimensional diatomic granular crystals composed of arrays of stainless steel spheres and cylinders interacting via Hertzian contact. The arrays consist of periodically repeated three-particle unit cells (sphere-cylinder-sphere) in which the length of the cylinder is varied systematically. We investigate the response of these granular crystals, given small amplitude dynamic displacements relative to those due to the static compression, and characterize their linear frequency spectrum. We find good agreement between theoretical dispersion relation analysis (for infinite systems), state-space analysis (for finite systems), and experiments. We report the observation of three distinct pass bands separated by two finite band gaps, and show their tunability for variations in cylinder length and static compression.", "doi": "10.1063/1.3556455", "issn": "0021-8979", "publisher": "American Institute of Physics", "publication": "Journal of Applied Physics", "publication_date": "2011-04-01", "series_number": "7", "volume": "109", "issue": "7", "pages": "Art. No. 074906" }, { "id": "authors:y0mnw-8de47", "collection": "authors", "collection_id": "y0mnw-8de47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110519-111956943", "type": "article", "title": "Interaction of highly nonlinear solitary waves with linear elastic media", "author": [ { "family_name": "Yang", "given_name": "Jinkyu", "clpid": "Yang-Jinkyu" }, { "family_name": "Silvestro", "given_name": "Claudio", "clpid": "Silvestro-C" }, { "family_name": "Khatri", "given_name": "Devvrath", "clpid": "Khatri-D" }, { "family_name": "De Nardo", "given_name": "Luigi", "orcid": "0000-0002-7492-6012", "clpid": "De-Nardo-L" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the interaction of highly nonlinear solitary waves propagating in granular crystals with an adjacent linear elastic medium. We investigate the effects of interface dynamics on the reflection of incident waves and on the formation of primary and secondary reflected waves. Experimental tests are performed to correlate the linear medium geometry, materials, and mass with the formation and propagation of reflected waves. We compare the experimental results with theoretical analysis based on the long-wavelength approximation and with numerical predictions obtained from discrete particle models. Experimental results are found to be in agreement with theoretical analysis and numerical simulations. This preliminary study establishes the foundation for utilizing reflected solitary waves as novel information carriers in nondestructive evaluation of elastic material systems.", "doi": "10.1103/PhysRevE.83.046606", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2011-04", "series_number": "4", "volume": "83", "issue": "4", "pages": "Art. No. 046606" }, { "id": "authors:yaw8p-7zg62", "collection": "authors", "collection_id": "yaw8p-7zg62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110429-104706086", "type": "article", "title": "Actuators for the generation of highly nonlinear solitary waves", "author": [ { "family_name": "Ni", "given_name": "Xianglei", "clpid": "Ni-Xianglei" }, { "family_name": "Rizzo", "given_name": "Piervincenzo", "clpid": "Rizzo-P" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "In this paper we present the design of two actuators for the generation of highly nonlinear solitary waves (HNSWs), which are mechanical waves that can form and travel in highly nonlinear systems. These waves are characterized by a constant spatial wavelength and by a tunable propagation speed, dependent on the wave amplitude. To date, the simplest and widely adopted method to generate HNSWs is by impacting a striker onto a chain of beads of equal size and mass. This operation is conducted manually and it might be impracticable if repetition rates higher than 0.1 Hz are necessary. It is known that the HNSWs' properties, such as amplitude, duration, and speed can be modified by changing the size or the material of the particles, the velocity of the striker, and/or the precompression on the chain. To address the limitations associated with the manual generation of HNSWs we designed, built, and tested two actuators. The first actuator consists of a chain of particles wrapped by an electromagnet that induces static precompression on the chain. This design allows for the generation of solitary waves with controlled properties. The second actuator consists of a chain surmounted by an electromagnet that lifts and releases a striker. This actuator permits the remote and noncontact generation of solitary waves. The performance of both actuators is evaluated by comparing the experimental HNSWs to theoretical predictions, based on the long wavelength approximation.", "doi": "10.1063/1.3556442", "issn": "0034-6748", "publisher": "American Institute of Physics", "publication": "Review of Scientific Instruments", "publication_date": "2011-03", "series_number": "3", "volume": "82", "issue": "3", "pages": "034902" }, { "id": "authors:7r5tj-6rs83", "collection": "authors", "collection_id": "7r5tj-6rs83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110321-150132745", "type": "article", "title": "Multiscale mass-spring models of carbon nanotube foams", "author": [ { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Blesgen", "given_name": "T.", "clpid": "Blesgen-T" }, { "family_name": "Amendola", "given_name": "A.", "orcid": "0000-0002-2562-881X", "clpid": "Amendola-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "This article is concerned with the mechanical properties of dense, vertically aligned CNT foams subject to one-dimensional compressive loading. We develop a discrete model directly inspired by the micromechanical response reported experimentally for CNT foams, where infinitesimal portions of the tubes are represented by collections of uniform bi-stable springs. Under cyclic loading, the given model predicts an initial elastic deformation, a non-homogeneous buckling regime, and a densification response, accompanied by a hysteretic unloading path. We compute the dynamic dissipation of such a model through an analytic approach. The continuum limit of the microscopic spring chain defines a mesoscopic dissipative element (micro-meso transition) which represents a finite portion of the foam thickness. An upper-scale model formed by a chain of non-uniform mesoscopic springs is employed to describe the entire CNT foam. A numerical approximation illustrates the main features of the proposed multiscale approach. Available experimental results on the compressive response of CNT foams are fitted with excellent agreement.", "doi": "10.1016/j.jmps.2010.09.004", "issn": "0022-5096", "publisher": "Elsevier", "publication": "Journal of the Mechanics and Physics of Solids", "publication_date": "2011-01", "series_number": "1", "volume": "59", "issue": "1", "pages": "89-102" }, { "id": "authors:j2jjr-f8s47", "collection": "authors", "collection_id": "j2jjr-f8s47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20101206-145418167", "type": "article", "title": "Intrinsic energy localization through discrete gap breathers in one-dimensional diatomic granular crystals", "author": [ { "family_name": "Theocharis", "given_name": "G.", "clpid": "Theocharis-G" }, { "family_name": "Boechler", "given_name": "N.", "clpid": "Boechler-N" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Job", "given_name": "S.", "clpid": "Job-S" }, { "family_name": "Porter", "given_name": "Mason A.", "clpid": "Porter-M-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We present a systematic study of the existence and stability of discrete breathers that are spatially localized\nin the bulk of a one-dimensional chain of compressed elastic beads that interact via Hertzian contact. The chain\nis diatomic, consisting of a periodic arrangement of heavy and light spherical particles. We examine two\nfamilies of discrete gap breathers: (1) an unstable discrete gap breather that is centered on a heavy particle and characterized by a symmetric spatial energy profile and (2) a potentially stable discrete gap breather that is\ncentered on a light particle and is characterized by an asymmetric spatial energy profile. We investigate their\nexistence, structure, and stability throughout the band gap of the linear spectrum and classify them into four\nregimes: a regime near the lower optical band edge of the linear spectrum, a moderately discrete regime, a\nstrongly discrete regime that lies deep within the band gap of the linearized version of the system, and a regime\nnear the upper acoustic band edge. We contrast discrete breathers in anharmonic Fermi-Pasta-Ulam (FPU)-type\ndiatomic chains with those in diatomic granular crystals, which have a tensionless interaction potential between\nadjacent particles, and note that the asymmetric nature of the tensionless interaction potential can lead to hybrid\nbulk-surface localized solutions.", "doi": "10.1103/PhysRevE.82.056604", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2010-11", "series_number": "5", "volume": "82", "issue": "5", "pages": "Art. No. 056604" }, { "id": "authors:cmyfm-v7w97", "collection": "authors", "collection_id": "cmyfm-v7w97", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100928-095305246", "type": "article", "title": "Highly nonlinear pulse splitting and recombination in a two-dimensional granular network", "author": [ { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Ngo", "given_name": "D.", "clpid": "Ngo-Duc" }, { "family_name": "Nesterenko", "given_name": "V. F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Fraternali", "given_name": "F.", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" } ], "abstract": "The propagation of highly nonlinear signals in a branched two-dimensional granular system was investigated experimentally and numerically for a system composed of chains of spherical beads of different materials. The system studied consists of a double Y-shaped guide in which high- and low-modulus/mass chains of spheres are arranged in various geometries. We observed the transformation of a single or a train of solitary pulses crossing the interface between branches. We report fast splitting of the initial pulse, rapid chaotization of the signal and impulse redirection and bending. Pulse and energy trapping was also observed in the branches. Numerical analysis based on Hertzian interaction between the particles and the side walls of the guide was found in agreement with the experimental data, except for nonsymmetric arrangements of particles excited by a large mass striker.", "doi": "10.1103/PhysRevE.82.036603", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2010-09-08", "series_number": "3", "volume": "82", "issue": "3", "pages": "Art. No. 036603" }, { "id": "authors:8gsyg-jh621", "collection": "authors", "collection_id": "8gsyg-jh621", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100831-090656085", "type": "article", "title": "Nonlinear waves in disordered diatomic granular chains", "author": [ { "family_name": "Ponson", "given_name": "Laurent", "clpid": "Ponson-L" }, { "family_name": "Boechler", "given_name": "Nicholas", "clpid": "Boechler-N" }, { "family_name": "Lai", "given_name": "Yi Ming", "clpid": "Lai-Yi-Ming" }, { "family_name": "Porter", "given_name": "Mason A.", "clpid": "Porter-M-A" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate the propagation and scattering of highly nonlinear waves in disordered granular chains composed of diatomic (two-mass) units of spheres that interact via Hertzian contact. Using ideas from statistical mechanics, we consider each diatomic unit to be a \"spin,\" so that a granular chain can be viewed as a spin chain composed of units that are each oriented in one of two possible ways. Experiments and numerical simulations both reveal the existence of two different mechanisms of wave propagation: in low-disorder chains, we observe the propagation of a solitary pulse with exponentially decaying amplitude. Beyond a critical level of disorder, the wave amplitude instead decays as a power law, and the wave transmission becomes insensitive to the level of disorder. We characterize the spatiotemporal structure of the wave in both propagation regimes and propose a simple theoretical interpretation for a transition between the two regimes. Our investigation suggests that an elastic spin chain can be used as a model system to investigate the role of heterogeneities in the propagation of highly nonlinear waves.", "doi": "10.1103/PhysRevE.82.021301", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2010-08", "series_number": "2", "volume": "82", "issue": "2", "pages": "Art. No. 021301" }, { "id": "authors:1z0jz-x3e77", "collection": "authors", "collection_id": "1z0jz-x3e77", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110321-090105511", "type": "article", "title": "Discrete Breathers in One-Dimensional Diatomic Granular Crystals", "author": [ { "family_name": "Boechler", "given_name": "N.", "clpid": "Boechler-N" }, { "family_name": "Theocharis", "given_name": "G.", "clpid": "Theocharis-G" }, { "family_name": "Job", "given_name": "S.", "clpid": "Job-S" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Porter", "given_name": "Mason A.", "clpid": "Porter-M-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We report the experimental observation of modulational instability and discrete breathers in a one-dimensional\ndiatomic granular crystal composed of compressed elastic beads that interact via Hertzian\ncontact. We first characterize their effective linear spectrum both theoretically and experimentally. We\nthen illustrate theoretically and numerically the modulational instability of the lower edge of the optical\nband. This leads to the dynamical formation of long-lived breather structures, whose families of solutions\nwe compute throughout the linear spectral gap. Finally, we experimentally observe the manifestation of\nthe modulational instability and the resulting generation of localized breathing modes with quantitative\ncharacteristics that agree with our numerical results.", "doi": "10.1103/PhysRevLett.104.244302", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2010-06-18", "series_number": "24", "volume": "104", "issue": "24", "pages": "Art. No. 244302" }, { "id": "authors:cntvr-83n62", "collection": "authors", "collection_id": "cntvr-83n62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100527-084237545", "type": "article", "title": "Generation and control of sound bullets with a nonlinear acoustic lens", "author": [ { "family_name": "Spadoni", "given_name": "Alessandro", "clpid": "Spadoni-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Acoustic lenses are employed in a variety of applications, from biomedical imaging and surgery to defense systems and damage detection in materials. Focused acoustic signals, for example, enable ultrasonic transducers to image the interior of the human body. Currently however the performance of acoustic devices is limited by their linear operational envelope, which implies relatively inaccurate focusing and low focal power. Here we show a dramatic focusing effect and the generation of compact acoustic pulses (sound bullets) in solid and fluid media, with energies orders of magnitude greater than previously achievable. This focusing is made possible by a tunable, nonlinear acoustic lens, which consists of ordered arrays of granular chains. The amplitude, size, and location of the sound bullets can be controlled by varying the static precompression of the chains. Theory and numerical simulations demonstrate the focusing effect, and photoelasticity experiments corroborate it. Our nonlinear lens permits a qualitatively new way of generating high-energy acoustic pulses, which may improve imaging capabilities through increased accuracy and signal-to-noise ratios and may lead to more effective nonintrusive scalpels, for example, for cancer treatment.", "doi": "10.1073/pnas.1001514107", "pmcid": "PMC2867709", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2010-04-20", "series_number": "16", "volume": "107", "issue": "16", "pages": "7230-7234" }, { "id": "authors:rwsq3-cqw85", "collection": "authors", "collection_id": "rwsq3-cqw85", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110524-092212206", "type": "book_section", "title": "Analytical and Experimental Analysis of Bandgaps in Nonlinear one Dimensional Periodic Structures", "book_title": "IUTAM Symposium on Recent Advances of Acoustic Waves in Solids", "author": [ { "family_name": "Boechler", "given_name": "Nicholas", "clpid": "Boechler-N" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Narisetti", "given_name": "Raj K.", "clpid": "Narisetti-R-K" }, { "family_name": "Ruzzene", "given_name": "M.", "orcid": "0000-0002-1502-2160", "clpid": "Ruzzene-M" }, { "family_name": "Leamy", "given_name": "M. J.", "clpid": "Leamy-M-J" } ], "contributor": [ { "family_name": "Wu", "given_name": "Tsung-Tsong", "clpid": "Wu-Tsung-Tsong" }, { "family_name": "Ma", "given_name": "Chien-Ching", "clpid": "Ma-Chien-Ching" } ], "abstract": "Wave propagation characteristics of nonlinear one-dimensional periodic structures are investigated analytically, numerically and experimentally. A novel perturbation analysis is first applied to predict the band gap location and extent in terms of linear and nonlinear system parameters. Approximate closed-form expressions capture the effect of nonlinearities on dispersion and depict amplitude dependent cut-off frequencies. The predictions from the perturbation analysis are verified through numerical simulations of harmonic wave motion. Results indicate the possibility of input amplitude as a tuning parameter through which cut-off frequencies can be adjusted to achieve filtering properties over selected frequency ranges. A periodic diatomic chain of stainless steel spheres alternating with aluminium spheres is experimentally investigated. The dynamic behavior of the chain is governed by Hertzian interaction of spheres and by a compressive pre-load which can be adjusted to obtain linear, weakly nonlinear and highly nonlinear behavior. For a weakly nonlinear case, preliminary results in experiments show the tendency for a shift in the band gap edges by varying input amplitude. The paper is a work in progress, for which the experimental results for a weakly nonlinear system are interpreted by the perturbation analysis developed for a specific case of linear and nonlinear power law interaction of exponent 3/2.", "doi": "10.1007/978-90-481-9893-1_20", "isbn": "978-90-481-9892-4", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "2010", "pages": "209-219" }, { "id": "authors:tteak-1nq72", "collection": "authors", "collection_id": "tteak-1nq72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100210-101923885", "type": "article", "title": "Optimal Design of Composite Granular Protectors", "author": [ { "family_name": "Fraternali", "given_name": "Fernando", "orcid": "0000-0002-7549-6405", "clpid": "Fraternali-F" }, { "family_name": "Porter", "given_name": "Mason A.", "clpid": "Porter-M-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We employ an evolutionary algorithm to investigate the optimal design of composite protectors using one-dimensional granular chains composed of beads of various sizes, masses, and stiffnesses. We define a fitness function using the maximum force transmitted from the protector to a \"wall\" that represents the body to be protected and accordingly optimize the topology (arrangement), size, and material of the chain. We obtain optimally randomized granular protectors characterized by high-energy equipartition and the transformation of incident waves into interacting solitary pulses. We consistently observe that the pulses traveling to the wall combine to form an extended (long-wavelength), small-amplitude pulse.", "doi": "10.1080/15376490802710779", "issn": "1537-6494", "publisher": "Taylor & Francis", "publication": "Mechanics of Advanced Materials and Structures", "publication_date": "2010", "series_number": "1", "volume": "17", "issue": "1", "pages": "1-19" }, { "id": "authors:191wj-5d857", "collection": "authors", "collection_id": "191wj-5d857", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100127-145522715", "type": "article", "title": "Localized breathing modes in granular crystals with defects", "author": [ { "family_name": "Theocharis", "given_name": "G.", "clpid": "Theocharis-G" }, { "family_name": "Kavousanakis", "given_name": "M.", "clpid": "Kavousanakis-M" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Porter", "given_name": "Mason A.", "clpid": "Porter-M-A" }, { "family_name": "Kevrekidis", "given_name": "I. G.", "clpid": "Kevrekidis-I-G" } ], "abstract": "We study localized modes in uniform one-dimensional chains of tightly packed and uniaxially compressed elastic beads in the presence of one or two light-mass impurities. For chains composed of beads of the same type, the intrinsic nonlinearity, which is caused by the Hertzian interaction of the beads, appears not to support localized, breathing modes. Consequently, the inclusion of light-mass impurities is crucial for their appearance. By analyzing the problem's linear limit, we identify the system's eigenfrequencies and the linear defect modes. Using continuation techniques, we find the solutions that bifurcate from their linear counterparts and study their linear stability in detail. We observe that the nonlinearity leads to a frequency dependence in the amplitude of the oscillations, a static mutual displacement of the parts of the chain separated by a defect, and for chains with two defects that are not in contact, it induces symmetry-breaking bifurcations.", "doi": "10.1103/PhysRevE.80.066601", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2009-12", "series_number": "6", "volume": "80", "issue": "6", "pages": "Art. No. 066601" }, { "id": "authors:ff2xq-d6553", "collection": "authors", "collection_id": "ff2xq-d6553", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100122-113115999", "type": "article", "title": "Hydrogen Evolution on Hydrophobic Aligned Carbon Nanotube Arrays", "author": [ { "family_name": "Misra", "given_name": "Abha", "clpid": "Misra-A" }, { "family_name": "Giri", "given_name": "Jyotsnendu", "clpid": "Giri-J" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We investigate for the first time hydrophobic carbon nanotube-based electrochemical cells as an alternative solution to hydrogen sorting. We show that the electrically conducting surface of the nanotube arrays can be used as a cathode for hydrogen generation and absorption by electrolyzing water. We support our findings with Raman and gas chromatography measurements. These results suggest that carbon nanotube forests, presenting a unique combination of hydrophobicity and conductivity, are suitable for application in fuel cells and microelectromechanical devices.", "doi": "10.1021/nn900878d", "issn": "1936-086X", "publisher": "American Chemical Society", "publication": "ACS Nano", "publication_date": "2009-12", "series_number": "12", "volume": "3", "issue": "12", "pages": "3903-3908" }, { "id": "authors:gdd6m-gth03", "collection": "authors", "collection_id": "gdd6m-gth03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100105-100308904", "type": "article", "title": "Stationary shocks in periodic highly nonlinear granular chains", "author": [ { "family_name": "Molinari", "given_name": "Alain", "clpid": "Molinari-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We study the existence of stationary shock waves in uniform and periodic heterogeneous highly nonlinear granular chains governed by a power-law contact interaction, comparing discrete and continuum approaches, as well as experiments. We report the presence of quasisteady shock fronts without the need for dissipative effects. When viscous effects are neglected, the structure of the leading front appears to be solely the result of dispersive effects related to the lattice wave dispersion and, for heterogeneous bead chains, to the impedance mismatch between material domains. We report analytically and numerically the shock-width scaling with the variation in the particles periodicity (cell size) and compare the obtained results with experiments. We check the state (\u2212) behind the shock front via quasistatic compression analysis and report a very good agreement between theory and numerical data.", "doi": "10.1103/PhysRevE.80.056602", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2009-11", "series_number": "5", "volume": "80", "issue": "5", "pages": "Art. No. 056602" }, { "id": "authors:wg1vr-jbz69", "collection": "authors", "collection_id": "wg1vr-jbz69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-080808608", "type": "book_section", "title": "Vibration Isolation via Linear and Nonlinear Periodic Devices", "book_title": "22nd Biennial Conference on Mechanical Vibration and Noise, Parts A and B", "author": [ { "family_name": "Spadoni", "given_name": "A.", "clpid": "Spadoni-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The current manuscripts deals with the design of passive mechanical filters for vibration attenuation a low frequencies. Traditionally, this has been addressed employing dissipation as the attenuation mechanism. While such strategy provides broad-frequency effectiveness, attenuation at any given frequency is modest. Mass and stiffness-modulated periodic systems, on the other hand, exploit dispersion as the attenuation mechanism and represent an alternative to dissipation-based devices. Attenuation due to dispersion may be significantly higher than what is afforded by dissipation-based systems within a design frequency rage. The proposed assemblies, however, are not easily tailored to filter lowe-frequency vibrations. To this end, embedding such periodic systems into an elastic matrix yields a high-pass mechanical filter with tunable stop bands were waves are not allowed to propagate. Significant improvements in performance moreover may be obtained if intrinsically nonlinear devices are adopted. Specifically, a strongly nonlinear medium such as ordered granular media supports a limited number of waveforms, resulting in an efficient mechanical filter. Results reported here, in fact, suggest matrix-embedded sphere chains as highly tunable mechanical filters for vibration attenuation.", "doi": "10.1115/DETC2009-87620", "isbn": "978-0-7918-4898-2", "publisher": "American Society of Mechanical Engineers", "place_of_publication": "New York, NY", "publication_date": "2009-09", "pages": "277-284" }, { "id": "authors:c6ppf-ny469", "collection": "authors", "collection_id": "c6ppf-ny469", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-083028476", "type": "book_section", "title": "An Experimental Investigation of Acoustic Band Gaps and Localization in Granular Elastic Chains", "book_title": "22nd Biennial Conference on Mechanical Vibration and Noise, Parts A and B", "author": [ { "family_name": "Boechler", "given_name": "Nicholas", "clpid": "Boechler-N" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We assembled a chain composed of a periodic arrangement of aluminum and steel spheres encased in a 4-rod polycarbonate holder with tunable static precompression applied by means of a lever actuated system. To excite periodic oscillations we perturbed the chain with a piezo-stack actuator driven by both continuous and finite bursts of a sinusoidally varying periodic signal. The amplitude of the periodic signal ranged from linear to strongly nonlinear regimes. We report the tunability of the frequency range for the band gap edges as a function of the material parameters, chain geometry and stress conditioning. We analyze the data by means of force-time plot and Fast Fourier Transforms (FFT). We observe a dramatic reduction of the transmitted wave amplitude for harmonic excitations with fundamental frequencies within the gap. The application of both continuous and short bursts of perturbation allows for observation of different dynamic phenomena at selected frequency ranges (in particular close to the lower optical branch edge). By varying the amplitude of the dynamic excitation (and therefore the level of the nonlinearity present in the system) we seek localized discrete breathing modes and surface instabilities. The comparison between continuum theory, discrete numerical modeling and experiments show a qualitative agreement and provide fundamental understanding for future investigation and numerous engineering applications. The challenges and considerations involved with the construction of an experimental system capable of capturing and leveraging on the described phenomena will be detailed.", "doi": "10.1115/DETC2009-87427", "isbn": "978-0-7918-4898-2", "publisher": "American Society of Mechanical Engineers", "place_of_publication": "New York, NY", "publication_date": "2009-09", "pages": "271-276" }, { "id": "authors:fpgqv-tqa89", "collection": "authors", "collection_id": "fpgqv-tqa89", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090903-152742278", "type": "article", "title": "Sharp Carbon-Nanotube Tips and Carbon-Nanotube Soldering Ions", "author": [ { "family_name": "Misra", "given_name": "Abha", "clpid": "Misra-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The nano-electron beam assisted fabrication of atomically sharp iron-based tips (see figure) and the creation of a nano-soldering iron for nano-interconnects using Fe-filled multiwalled carbon nanotubes (MWCNTs) is reported. The technique allows carving of a MWCNT and a control of the flow of the encapsulated metal outward by regulating the e-beam exposure time and spot size.", "doi": "10.1002/adma.200801893", "issn": "0935-9648", "publisher": "Wiley", "publication": "Advanced Materials", "publication_date": "2009-06-12", "series_number": "22", "volume": "21", "issue": "22", "pages": "2305-2308" }, { "id": "authors:ey8j8-h4p71", "collection": "authors", "collection_id": "ey8j8-h4p71", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-154057222", "type": "article", "title": "Sharp Carbon-Nanotube Tips and Carbon-Nanotube Soldering Irons", "author": [ { "family_name": "Misra", "given_name": "Abha", "clpid": "Misra-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "The nano-electron beam assisted fabrication of atomically sharp iron-based tips (see figure) and the creation of a nano-soldering iron for nano-interconnects using Fe-filled multiwalled carbon nanotubes (MWCNTs) is reported. The technique allows carving of a MWCNT and a control of the flow of the encapsulated metal outward by regulating the e-beam exposure time and spot size.", "doi": "10.1002/adma.200801893", "issn": "0935-9648", "publisher": "Wiley", "publication": "Advanced Materials", "publication_date": "2009-06-12", "series_number": "22", "volume": "21", "issue": "22", "pages": "2305-2308" }, { "id": "authors:vkctk-g9h14", "collection": "authors", "collection_id": "vkctk-g9h14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090611-150011809", "type": "article", "title": "Pulse propagation in a linear and nonlinear diatomic periodic chain: effects of acoustic frequency band-gap", "author": [ { "family_name": "Herbold", "given_name": "E. B.", "clpid": "Herbold-E-B" }, { "family_name": "Kim", "given_name": "J.", "clpid": "Kim-J" }, { "family_name": "Nesterenko", "given_name": "V. F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Wang", "given_name": "S. Y.", "clpid": "Wang-S-Y" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "One-dimensional nonlinear phononic crystals have been assembled from periodic diatomic chains of stainless steel cylinders alternated with Polytetrafluoroethylene spheres. This system allows dramatic changes of behavior (from linear to strongly nonlinear) by application of compressive forces practically without changes of geometry of the system. The relevance of classical acoustic band-gap, characteristic for chain with linear interaction forces and derived from the dispersion relation of the linearized system, on the transformation of single and multiple pulses in linear, nonlinear and strongly nonlinear regimes are investigated with numerical calculations and experiments. The limiting frequencies of the acoustic band-gap for investigated system with given precompression force are within the audible frequency range (20\u201320,000 Hz) and can be tuned by varying the particle's material properties, mass and initial compression. In the linear elastic chain the presence of the acoustic band-gap was apparent through fast transformation of incoming pulses within very short distances from the chain entrance. It is interesting that pulses with relatively large amplitude (nonlinear elastic chain) exhibit qualitatively similar behavior indicating relevance of the acoustic band gap also for transformation of nonlinear signals. The effects of an in situ band-gap created by a mean dynamic compression are observed in the strongly nonlinear wave regime.", "doi": "10.1007/s00707-009-0163-6", "issn": "0001-5970", "publisher": "Springer", "publication": "Acta Mechanica", "publication_date": "2009-06", "series_number": "1-4", "volume": "205", "issue": "1-4", "pages": "85-103" }, { "id": "authors:91qac-31320", "collection": "authors", "collection_id": "91qac-31320", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090602-080000941", "type": "article", "title": "Highly nonlinear solitary waves in heterogeneous periodic granular media", "author": [ { "family_name": "Porter", "given_name": "Mason A.", "clpid": "Porter-M-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Szelengowicz", "given_name": "Ivan", "clpid": "Szelengowicz-I" }, { "family_name": "Herbold", "given_name": "Eric B.", "clpid": "Herbold-E-B" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" } ], "abstract": "We use experiments, numerical simulations, and theoretical analysis to investigate the propagation of highly nonlinear solitary waves in periodic arrangements of dimer (two-mass) and trimer (three-mass) cell structures in one-dimensional granular lattices. To vary the composition of the fundamental periodic units in the granular chains, we utilize beads of different materials (stainless steel, brass, glass, nylon, polytetrafluoroethylene, and rubber). This selection allows us to tailor the response of the system based on the masses, Poisson ratios, and elastic moduli of the components. For example, we examine dimer configurations with two types of heavy particles, two types of light particles, and alternating light and heavy particles. Employing a model with Hertzian interactions between adjacent beads, we find good agreement between experiments and numerical simulations. We also find good agreement between these results and a theoretical analysis of the model in the long-wavelength regime that we derive for heterogeneous environments (dimer chains) and general bead interactions. Our analysis encompasses previously-studied examples as special cases and also provides key insights on the influence of heterogeneous lattices on the properties (width and propagation speed) of the nonlinear wave solutions of this system.", "doi": "10.1016/j.physd.2008.12.010", "issn": "0167-2789", "publisher": "Elsevier", "publication": "Physica D", "publication_date": "2009-04-01", "series_number": "6", "volume": "238", "issue": "6", "pages": "666-676" }, { "id": "authors:gzx96-hp011", "collection": "authors", "collection_id": "gzx96-hp011", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-134905089", "type": "book_section", "title": "Novel sensor technology for NDE of concrete", "book_title": "Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems", "author": [ { "family_name": "Ni", "given_name": "Xianglei", "clpid": "Ni-Xianglei" }, { "family_name": "Rizzo", "given_name": "Piervincenzo", "clpid": "Rizzo-P" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "contributor": [ { "family_name": "Tomizuka", "given_name": "Masayoshi", "clpid": "Tomizuka-Masayoshi" }, { "family_name": "Yun", "given_name": "Chung-Bang", "clpid": "Yun-Chung-Bang" }, { "family_name": "Giurgiutiu", "given_name": "Victor", "clpid": "Giurgiutiu-V" } ], "abstract": "This paper describes the application of a novel actuator/sensor technology for the generation and detection of stress waves in structural materials like concrete. The technology is aimed at developing an innovative NDE scheme based on the generation of highly nonlinear solitary waves (HNSWs). HNSWs are stress waves that can form and travel in highly nonlinear systems (i.e. granular, layered, fibrous or porous materials) with a finite spatial dimension independent on the wave amplitude. Compared to conventional linear waves, the generation of HNSWs does not rely on the use of electronic equipment (such as an arbitrary function generator) and on the response of piezoelectric crystals or other transduction mechanism. The results of using these new actuator/sensors to test concrete slabs are presented and discussed.", "doi": "10.1117/12.815510", "isbn": "9780819475527", "publisher": "Society of Photo-optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2009-03-30", "pages": "Art. No. 72918-1" }, { "id": "authors:d7j0r-38v97", "collection": "authors", "collection_id": "d7j0r-38v97", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-131950659", "type": "book_section", "title": "Coupling of Highly Nonlinear Waves with Linear Elastic Media", "book_title": "Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems", "author": [ { "family_name": "Khatri", "given_name": "Devvrath", "clpid": "Khatri-D" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Rizzo", "given_name": "Piervincenzo", "clpid": "Rizzo-P" } ], "contributor": [ { "family_name": "Tomizuka", "given_name": "Masayoshi", "clpid": "Tomizuka-Masayoshi" }, { "family_name": "Yun", "given_name": "Chung-Bang", "clpid": "Yun-Chung-Bang" }, { "family_name": "Giurgiutiu", "given_name": "Victor", "clpid": "Giurgiutiu-V" } ], "abstract": "This paper reports a fundamental study of the coupling between highly nonlinear waves, generated in a one dimensional granular chain of particles, with linear elastic media, for the development of a new Non Destructive Evaluation and Structural Health Monitoring (NDE/SHM) paradigm. We design and use novel acoustic actuators to excite compact highly nonlinear solitary waves in a one-dimensional linear elastic rod and investigate the pulse propagation across the interface. To model the actuator and rod system we use Finite Element Analysis (Abaqus) and obtain excellent agreement between the experimental observations and the numerical results. We also study the response of the system to the presence of defects (cracks) in the steel rod, by comparing the wave propagation properties in pristine and cracked test objects. The obtained results encourage the use of highly nonlinear waves as an effective tool for developing a new, viable NDE/SHM method.", "doi": "10.1117/12.817574", "isbn": "9780819475527", "publisher": "Society of Photo-optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2009-03-30", "pages": "Art. No. 72920P" }, { "id": "authors:azn3d-39v97", "collection": "authors", "collection_id": "azn3d-39v97", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090806-085230553", "type": "article", "title": "Strain rate effects in the mechanical response of polymer-anchored carbon nanotube foams", "author": [ { "family_name": "Misra", "given_name": "Abha", "clpid": "Misra-A" }, { "family_name": "Greer", "given_name": "Julia R.", "orcid": "0000-0002-9675-1508", "clpid": "Greer-J-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Strain rate effects on the mechanical properties of carbon nanotube forests are studied, and several related interesting new phenomena are reported. Dense vertically aligned foam-like forests of carbon nanotubes are anchored on a thin, flexible polymer layer to provide structural stability, particularly at the higher strain rates. Permanent deformation and for the first time the delamination and crumbling of carbon nanotube walls is observed.", "doi": "10.1002/adma.200801997", "issn": "0935-9648", "publisher": "Wiley", "publication": "Advanced Materials", "publication_date": "2009-01-19", "series_number": "3", "volume": "21", "issue": "3", "pages": "334-338" }, { "id": "authors:9b096-5d417", "collection": "authors", "collection_id": "9b096-5d417", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:CARprl09", "type": "article", "title": "Dissipative Solitary Waves in Granular Crystals", "author": [ { "family_name": "Carretero-Gonz\u00e1lez", "given_name": "R.", "clpid": "Carretero-Gonz\u00e1lez-R" }, { "family_name": "Khatri", "given_name": "D.", "clpid": "Khatri-D" }, { "family_name": "Porter", "given_name": "Mason A.", "clpid": "Porter-M-A" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "We provide a quantitative characterization of dissipative effects in one-dimensional granular crystals. We use the propagation of highly nonlinear solitary waves as a diagnostic tool and develop optimization schemes that allow one to compute the relevant exponents and prefactors of the dissipative terms in the equations of motion. We thereby propose a quantitatively accurate extension of the Hertzian model that encompasses dissipative effects via a discrete Laplacian of the velocities. Experiments and computations with steel, brass, and polytetrafluoroethylene reveal a common dissipation exponent with a material-dependent prefactor.", "doi": "10.1103/PhysRevLett.102.024102", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2009-01-16", "series_number": "2", "volume": "102", "issue": "2", "pages": "Art. No. 024102" }, { "id": "authors:qq2x1-h7r58", "collection": "authors", "collection_id": "qq2x1-h7r58", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160322-073625782", "type": "monograph", "title": "Tunable frequency band-gap and pulse propagation in a strongly nonlinear diatomic chain", "author": [ { "family_name": "Herbold", "given_name": "E. B.", "clpid": "Herbold-E-B" }, { "family_name": "Nesterenko", "given_name": "V. F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Wang", "given_name": "S.", "clpid": "Wang-S" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "One-dimensional nonlinear phononic crystals have been assembled from periodic diatomic chains of stainless steel cylinders alternated with Polytetrafluoroethylene (PTFE)\nspheres. We report the presence of acoustic band gaps in the dispersion relation of the linearized systems and study the transformation of single and multiple pulses in linear,\nnonlinear and strongly nonlinear regimes with numerical calculations and experiments. The limiting frequencies of the band gap are within the audible frequency range (20~20,000 Hz) and can be tuned by varying the particle's material properties, mass and initial compression.\nPulses rapidly transform within very short distances from the impacted end due to the influence of the band gap in the linear and in nonlinear elastic chain. The effects of an in situ band gap created by a mean dynamic compression are observed in the strongly nonlinear wave regime.", "doi": "10.48550/arXiv.0806.4225", "publication_date": "2008-06-26" }, { "id": "authors:wev40-gae12", "collection": "authors", "collection_id": "wev40-gae12", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-130447803", "type": "book_section", "title": "Highly Nonlinear Waves' Sensor Technology for Highway Infrastructures", "book_title": "Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2008", "author": [ { "family_name": "Khatri", "given_name": "Devvrath", "clpid": "Khatri-D" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Rizzo", "given_name": "Piervincenzo", "clpid": "Rizzo-P" } ], "contributor": [ { "family_name": "Shull", "given_name": "P. J.", "clpid": "Shull-P-J" }, { "family_name": "Wu", "given_name": "H. F.", "clpid": "Wu-H-F" }, { "family_name": "Diaz", "given_name": "A. A.", "clpid": "Diaz-A-A" }, { "family_name": "Vogel", "given_name": "D. W.", "clpid": "Vogel-D-W" } ], "abstract": "This paper describes preliminary results towards the development of an innovative NDE/SHM scheme for material characterization and defect detection based on the generation of highly nonlinear solitary waves (HNSWs). HNSWs are stress waves that can form and travel in highly nonlinear systems (i.e. granular, layered, fibrous or porous materials) with a finite spatial dimension independent on the wave amplitude. Compared to conventional linear waves, the generation of HNSWs does not rely on the use of electronic equipment (such as an arbitrary function generator) and on the response of piezoelectric crystals or other transduction mechanism. HNSWs possess unique tunable properties that provide a complete control over tailoring: 1) the choice of the wave's width (spatial size) for defects investigation, 2) the composition of the excited train of waves (i.e. number and separation of the waves used for testing), and 3) their amplitude and velocity. HNSWs are excited onto concrete samples and steel rebar. The first pilot study of this ongoing effort between Caltech and the University of Pittsburgh is presented.", "doi": "10.1117/12.775848", "isbn": "978-0-8194-7120-8", "publisher": "Society of Photo-optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2008-04-08", "pages": "Art. No. 9340" }, { "id": "authors:0sbd0-t6k79", "collection": "authors", "collection_id": "0sbd0-t6k79", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180723-114843030", "type": "book_section", "title": "Highly nonlinear waves' sensor technology for highway infrastructures", "book_title": "Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2008", "author": [ { "family_name": "Khatri", "given_name": "Devvrath", "clpid": "Khatri-D" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Rizzo", "given_name": "Piervincenzo", "clpid": "Rizzo-P" } ], "contributor": [ { "family_name": "Shull", "given_name": "Peter J.", "clpid": "Shull-P-J" }, { "family_name": "Wu", "given_name": "H. Felix", "clpid": "Wu-H-Felix" }, { "family_name": "Diaz", "given_name": "Aaron A.", "clpid": "Diaz-A-A" }, { "family_name": "Vogel", "given_name": "Dietmar W.", "clpid": "Vogel-D-W" } ], "abstract": "This paper describes preliminary results towards the development of an innovative NDE/SHM scheme for material characterization and defect detection based on the generation of highly nonlinear solitary waves (HNSWs). HNSWs are stress waves that can form and travel in highly nonlinear systems (i.e. granular, layered, fibrous or porous materials) with a finite spatial dimension independent on the wave amplitude. Compared to conventional linear waves, the generation of HNSWs does not rely on the use of electronic equipment (such as an arbitrary function generator) and on the response of piezoelectric crystals or other transduction mechanism. HNSWs possess unique tunable properties that provide a complete control over tailoring: 1) the choice of the wave's width (spatial size) for defects investigation, 2) the composition of the excited train of waves (i.e. number and separation of the waves used for testing), and 3) their amplitude and velocity. HNSWs are excited onto concrete samples and steel rebar. The first pilot study of this ongoing effort between Caltech and the University of Pittsburgh is presented.", "doi": "10.1117/12.775848", "isbn": "9780819471208", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-04-08", "pages": "Art. No. 69340U" }, { "id": "authors:6kbny-24c46", "collection": "authors", "collection_id": "6kbny-24c46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-074435784", "type": "book_section", "title": "Entanglement and the Nonlinear Elastic Behavior of Forests of Coiled Carbon Nanotubes", "book_title": "Carbon nanotubes and related low-dimensional materials", "author": [ { "family_name": "Coluci", "given_name": "Vitor R.", "clpid": "Coluci-V-R" }, { "family_name": "Fonseca", "given_name": "Alexandre F.", "clpid": "Fonseca-A-F" }, { "family_name": "Galvao", "given_name": "Douglas S.", "clpid": "Galvao-D-S" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "contributor": [ { "family_name": "Chen", "given_name": "Li-Chyong", "clpid": "Chen-Li-Chyong" } ], "abstract": "A model for the elastic response of a foamlike forest of coiled carbon nanotubes under mechanical impact is proposed according to recent experiments reported in the literature. A force vs. displacement relation is derived for different geometries of the impacting object (sphere, cube and circular cone). In the model, entanglement among neighboring coils in the superior part of the forest is explicitly taken into account and we show that it allows the full description of the strongly nonlinear elastic behavior of the forest.", "doi": "10.1557/PROC-1081-P08-24", "isbn": "9781605110516", "publisher": "Materials Research Society", "place_of_publication": "Warrendale, PA", "publication_date": "2008-03", "pages": "1081-P08" }, { "id": "authors:abhta-p0m60", "collection": "authors", "collection_id": "abhta-p0m60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:COLprl08", "type": "article", "title": "Entanglement and the Nonlinear Elastic Behavior of Forests of Coiled Carbon Nanotubes", "author": [ { "family_name": "Coluci", "given_name": "V. R.", "clpid": "Coluci-V-R" }, { "family_name": "Fonseca", "given_name": "A. F.", "clpid": "Fonseca-A-F" }, { "family_name": "Galv\u00e3o", "given_name": "D. S.", "clpid": "Galv\u00e3o-D-S" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "abstract": "Helical or coiled nanostructures have been objects of intense experimental and theoretical studies due to their special electronic and mechanical properties. Recently, it was experimentally reported that the dynamical response of a foamlike forest of coiled carbon nanotubes under mechanical impact exhibits a nonlinear, non-Hertzian behavior, with no trace of plastic deformation. The physical origin of this unusual behavior is not yet fully understood. In this Letter, based on analytical models, we show that the entanglement among neighboring coils in the superior part of the forest surface must be taken into account for a full description of the strongly nonlinear behavior of the impact response of a drop ball onto a forest of coiled carbon nanotubes.", "doi": "10.1103/PhysRevLett.100.086807", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2008-02-29", "series_number": "8", "volume": "100", "issue": "8", "pages": "Art. No. 086807" }, { "id": "authors:yazxn-4mp08", "collection": "authors", "collection_id": "yazxn-4mp08", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:PORpre08", "type": "article", "title": "Highly nonlinear solitary waves in periodic dimer granular chains", "author": [ { "family_name": "Porter", "given_name": "Mason A.", "clpid": "Porter-M-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Herbold", "given_name": "Eric B.", "clpid": "Herbold-E-B" }, { "family_name": "Szelengowicz", "given_name": "Ivan", "clpid": "Szelengowicz-I" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" } ], "abstract": "We investigate the propagation of highly nonlinear solitary waves in heterogeneous, periodic granular media using experiments, numerical simulations, and theoretical analysis. We examine periodic arrangements of particles in experiments in which stiffer and heavier beads (stainless steel) are alternated with softer and lighter ones (polytetrafluoroethylene beads). We find good agreement between experiments and numerics in a model with Hertzian interactions between adjacent beads, which in turn agrees very well with a theoretical analysis of the model in the long-wavelength regime that we derive for heterogeneous environments and general bead interactions. Our analysis encompasses previously studied examples as special cases and also provides key insights into the influence of the dimer lattice on the properties (width and propagation speed) of the highly nonlinear wave solutions.", "doi": "10.1103/PhysRevE.77.015601", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2008-01", "series_number": "1", "volume": "77", "issue": "1", "pages": "Art. No. 015601(R)" }, { "id": "authors:1a03w-6rj82", "collection": "authors", "collection_id": "1a03w-6rj82", "cite_using_url": "https://resolver.caltech.edu/CaltechSOLIDS:2007.002", "type": "monograph", "title": "Highly Nonlinear Solitary Waves in Periodic Dimer Granular Chains", "author": [ { "family_name": "Porter", "given_name": "Mason A.", "clpid": "Porter-M-A" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Herbold", "given_name": "Eric B.", "clpid": "Herbold-E-B" }, { "family_name": "Szelengowicz", "given_name": "Ivan", "clpid": "Szelengowicz-I" }, { "family_name": "Kevrekidis", "given_name": "P. G.", "orcid": "0000-0002-7714-3689", "clpid": "Kevrekidis-P-G" } ], "abstract": "We report the propagation of highly nonlinear solitary waves in heterogeneous, periodic granular media using experiments, numerical simulations, and theoretical analysis. We examine periodic arrangements of particles in experiments in which stiffer/heavier beads (stainless steel) are alternated with softer/lighter ones (polytetrafluoroethylene beads). We find excellent agreement between experiments and numerics in a model with Hertzian interactions between adjacent beads, which in turn agrees very well with a theoretical analysis of the model in the long-wavelength regime that we derive for heterogeneous environments and general bead interactions. Our analysis encompasses previously-studied examples as special cases and also provides key insights on the influence of the dimer lattice on the properties (width and propagation speed) of the obtained highly nonlinear wave\nsolutions.", "publisher": "Physical Review E", "publication_date": "2007-12-14" }, { "id": "authors:rqte6-abr70", "collection": "authors", "collection_id": "rqte6-abr70", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DARaipcp07", "type": "book_section", "title": "Propagation of highly nonlinear signals in a two dimensional network of granular chains", "book_title": "Shock Compression of Condensed Matter - 2007: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter, Waikoloa, HI, 24\u201329 June 2007", "author": [ { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Nesterenko", "given_name": "V. F.", "clpid": "Nesterenko-V-F" } ], "contributor": [ { "family_name": "Elert", "given_name": "Mark" }, { "family_name": "Furnish", "given_name": "Michael D." }, { "family_name": "Chau", "given_name": "Ricky" }, { "family_name": "Holmes", "given_name": "Neil" }, { "family_name": "Nguyen", "given_name": "Jeffrey" } ], "abstract": "We report the first experimental observation of highly nonlinear signals propagating in a two dimensional system composed of granular chains. In this system one of the chains contacts two others to allow splitting and redirecting the solitary-like signal formed in the first chain. The system consists of a double Y-shaped guide in which high- and low-modulus chains of spheres are arranged in various geometries. We observed fast splitting of the initial pulse, rapid chaotization of the signal and sharp bending of the propagating acoustic information. Pulse and energy trapping was also observed in composite systems assembled from hard- and soft-particles in the branches.", "doi": "10.1063/1.2832991", "isbn": "978-0-7354-0469-4", "publisher": "American Institute of Physics", "place_of_publication": "Melville, NY", "publication_date": "2007-12-12", "pages": "1419-1422" }, { "id": "authors:0zgah-c4n31", "collection": "authors", "collection_id": "0zgah-c4n31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BANjap07", "type": "article", "title": "A plausible mechanism for the evolution of helical forms in nanostructure growth", "author": [ { "family_name": "Bandaru", "given_name": "P. R.", "clpid": "Bandaru-P-R" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Yang", "given_name": "K.", "clpid": "Yang-K" }, { "family_name": "Rao", "given_name": "A. M.", "clpid": "Rao-A-M" } ], "abstract": "The observation of helices and coils in nano-tube/-fiber (NT/NF) syntheses is explained on the basis of the interactions between specific catalyst particles and the growing nanostructure. In addition to rationalizing nonlinear structure, the proposed model probes the interplay between thermodynamic quantities and predicts conditions for optimal growth. Experimental results on the effect of indium catalyst on affecting the coil pitch in NTs and NFs are presented.", "doi": "10.1063/1.2723189", "issn": "0021-8979", "publisher": "Journal of Applied Physics", "publication": "Journal of Applied Physics", "publication_date": "2007-05-01", "series_number": "9", "volume": "101", "issue": "9", "pages": "Art. No. 094307" }, { "id": "authors:mq8bh-8dp34", "collection": "authors", "collection_id": "mq8bh-8dp34", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161003-151554509", "type": "article", "title": "Atomic Force Microscopy Imaging and Electrical Recording of Lipid Bilayers Supported over Microfabricated Silicon Chip Nanopores: Lab-on-a-Chip System for Lipid Membranes and Ion Channels", "author": [ { "family_name": "Quist", "given_name": "Arjan P.", "clpid": "Quist-A-P" }, { "family_name": "Chand", "given_name": "Ami", "clpid": "Chand-A" }, { "family_name": "Ramachandran", "given_name": "Srinivasan", "clpid": "Ramachandran-S" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Jin", "given_name": "Sungho", "clpid": "Jin-Sungho" }, { "family_name": "Lal", "given_name": "Ratnesh", "clpid": "Lal-R" } ], "abstract": "We describe a silicon chip-based supported bilayer system to detect the presence of ion channels and their electrical conductance in lipid bilayers. Nanopores were produced in microfabricated silicon membranes by electron beam lithography as well as by using a finely focused ion beam. Thermal oxide was used to shrink pore sizes, if necessary, and to create an insulating surface. The chips with well-defined pores were easily mounted on a double-chamber plastic cell recording system, allowing for controlling the buffer conditions both above and below the window. The double-chamber system allowed using an atomic force microscopy (AFM) tip as one electrode and inserting a platinum wire as the second electrode under the membrane window, to measure electrical current across lipid bilayers that are suspended over the pores. Atomic force imaging, stiffness measurement, and electrical capacitance measurement show the feasibility of supporting lipid bilayers over defined nanopores:\u2009 a key requirement to use any such technique for structure\u2212function study of ion channels. Online addition of gramicidin, an ion-channel-forming peptide, resulted in electrical current flow across the bilayer, and the I\u2212V curve that was measured using the conducting AFM tip indicates the presence of many conducting gramicidin ion channels.", "doi": "10.1021/la062187z", "issn": "0743-7463", "publisher": "American Chemical Society", "publication": "Langmuir", "publication_date": "2007-01-30", "series_number": "3", "volume": "23", "issue": "3", "pages": "1375-1380" }, { "id": "authors:1af91-b6b30", "collection": "authors", "collection_id": "1af91-b6b30", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-103736251", "type": "article", "title": "Impact response by a foamlike forest of coiled carbon nanotubes", "author": [ { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Nesterenko", "given_name": "Vitali F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Jin", "given_name": "Sungho", "clpid": "Jin-Sungho" }, { "family_name": "Wang", "given_name": "Wei", "orcid": "0000-0002-5257-7675", "clpid": "Wang-Wei" }, { "family_name": "Rao", "given_name": "Apparao M.", "clpid": "Rao-A-M" } ], "abstract": "We studied the dynamic response of a foamlike forest of coiled carbon nanotubes under high strain rate deformation using a simple drop-ball test. The method is based on measuring the dynamic force between the ball and the foam on the substrate during the stages of penetration and restitution. The analysis of the forest's morphology after impact has shown no trace of plastic deformation and a full recovery of the foamlike layer of coiled carbon nanotubes under various impact velocities. The contact force exhibits a strongly nonlinear dependence on displacement and appears fundamentally different from the response of a forest of straight carbon nanotubes, and from the Hertzian type of plane-sphere interaction. \"Brittle\" fracture of the foamlike layer is observed after repeated high velocity impacts. Such layers of coiled nanotubes may be used as a strongly nonlinear spring in discrete systems for monitoring their dynamic behavior and as a nanostructure for localized microimpact protection.", "doi": "10.1063/1.2345609", "issn": "0021-8979", "publisher": "American Institute of Physics", "publication": "Journal of Applied Physics", "publication_date": "2006-09-15", "series_number": "6", "volume": "100", "issue": "6", "pages": "Art. No. 064309" }, { "id": "authors:bkc2n-tgf68", "collection": "authors", "collection_id": "bkc2n-tgf68", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HERaipcp06", "type": "book_section", "title": "Influence of Controlled Viscous Dissipation on the Propagation of Strongly Nonlinear Waves in Stainless Steel Based Phononic Crystals", "book_title": "Shock compression of condensed matter--2005 : proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter held at Baltimore, MD 31 July-5 August, 2005", "author": [ { "family_name": "Herbold", "given_name": "Eric B.", "clpid": "Herbold-E-B" }, { "family_name": "Nesterenko", "given_name": "Vitali F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" } ], "contributor": [ { "family_name": "Furnish", "given_name": "Michael D.", "clpid": "Furnish-M-D" }, { "family_name": "Elert", "given_name": "Mark L.", "clpid": "Elert-M-L" }, { "family_name": "Russell", "given_name": "Thomas P.", "clpid": "Russell-T-P" }, { "family_name": "White", "given_name": "Carter T.", "clpid": "White-C-T" } ], "abstract": "Strongly nonlinear phononic crystals were assembled from stainless steel spheres. Single solitary waves and splitting of an initial pulse into a train of solitary waves were investigated in different viscous media using motor oil and non-aqueous glycerol to introduce a controlled viscous dissipation. Experimental results indicate that the presence of a viscous fluid dramatically altered the splitting of the initial pulse into a train of solitary waves. Numerical simulations qualitatively describe the observed phenomena only when a dissipative term based on the relative velocity between particles is introduced.", "doi": "10.1063/1.2263614", "isbn": "0-7354-0341-4", "publisher": "American Institute of Physics", "place_of_publication": "Melville, NY", "publication_date": "2006-07-28", "pages": "1523-1526" }, { "id": "authors:h689z-75108", "collection": "authors", "collection_id": "h689z-75108", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DARaipcp06", "type": "book_section", "title": "Strongly Nonlinear Waves in Polymer Based Phononic Crystals", "book_title": "Shock compression of condensed matter--2005 : proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter held at Baltimore, MD 31 July-5 August, 2005", "author": [ { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Nesterenko", "given_name": "V. F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Herbold", "given_name": "E. B.", "clpid": "Herbold-E-B" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-S" } ], "contributor": [ { "family_name": "Furnish", "given_name": "Michael D.", "clpid": "Fiurnish-M-D" }, { "family_name": "Elert", "given_name": "Mark L.", "clpid": "Elert-M-L" }, { "family_name": "Russell", "given_name": "Thomas P.", "clpid": "Russell-T-P" }, { "family_name": "White", "given_name": "Carter T.", "clpid": "White-C-T" } ], "abstract": "One dimensional \"sonic vacuum\"-type phononic crystals were assembled from chains of polytetrafluoroethylene (PTFE) beads and Parylene coated spheres with different diameters. It was demonstrated for the first time that these polymer-based granular system, with exceptionally low elastic modulus of particles, support the propagation of strongly nonlinear solitary waves with a very low speed. They can be described using classical nonlinear Hertz law despite the viscoelastic nature of the polymers and the high strain rate deformation of the contact area. Trains of strongly nonlinear solitary waves excited by an impact were investigated experimentally and were found to be in reasonable agreement with numerical calculations. Tunability of the signal shape and velocity was achieved through a non-contact magnetically induced precompression of the chains. This applied prestress allowed an increase of up to two times the solitary waves speed and significant delayed the signal splitting. Anomalous reflection at the interface of two \"sonic vacua\"-type systems was reported.", "doi": "10.1063/1.2263610", "isbn": "0-7354-0341-4", "publisher": "American Institute of Physics", "place_of_publication": "Melville, NY", "publication_date": "2006-07-28", "pages": "1507-1510" }, { "id": "authors:6tjg1-fhy40", "collection": "authors", "collection_id": "6tjg1-fhy40", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161003-143007657", "type": "article", "title": "Pulse mitigation by a composite discrete medium", "author": [ { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Nesterenko", "given_name": "V. F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Herbold", "given_name": "E. B.", "clpid": "Herbold-E-B" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" } ], "abstract": "The strongly nonlinear interaction between elements in discrete materials (e.g., grains in granular media) is responsible for their unique wave propagation properties. The paper will present an experimental observation of impulse energy confinement and the resultant disintegration of shock and solitary waves by discrete materials with strongly nonlinear interaction between elements. Experiments and numerical calculations will be presented for alternating ensembles of high-modulus vs orders of magnitude lower-modulus chains of spheres of different masses. The trapped energy is contained within the \"softer\" portions of the composite chain and is slowly released in the form of weak, separated pulses over an extended period of time. This effect is enhanced by using a specific group assembly and a superimposed force.", "doi": "10.1051/jp4:2006134073", "issn": "1155-4339", "publisher": "EDP Sciences", "publication": "Journal de Physique IV (Proceedings)", "publication_date": "2006-07-26", "volume": "134", "pages": "473-479" }, { "id": "authors:7v981-bgd83", "collection": "authors", "collection_id": "7v981-bgd83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161005-073226212", "type": "article", "title": "Significantly accelerated osteoblast cell growth on aligned TiO_2 nanotubes", "author": [ { "family_name": "Oh", "given_name": "Seunghan", "clpid": "Oh-Seunghan" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Chen", "given_name": "Li-Han", "clpid": "Chen-Li-Han" }, { "family_name": "Pisanic", "given_name": "Thomas R.", "clpid": "Pisanic-T-R" }, { "family_name": "Fino\u00f1es", "given_name": "Rita R.", "clpid": "Fino\u00f1es-R-R" }, { "family_name": "Jin", "given_name": "Sungho", "clpid": "Jin-Sungho" } ], "abstract": "Vertically aligned yet laterally spaced nanoscale TiO2 nanotubes have been grown on Ti by anodization, and the growth of MC3T3-E1 osteoblast cells on such nanotubes has been investigated. The adhesion/propagation of the osteoblast is substantially improved by the topography of the TiO_2 nanotubes with the filopodia of growing cells actually going into the nanotube pores, producing an interlocked cell structure. The presence of the nanotube structure induced a significant acceleration in the growth rate of osteoblast cells by as much as \u223c300\u2013400%.", "doi": "10.1002/jbm.a.30722", "issn": "1549-3296", "publisher": "John Wiley & Sons", "publication": "Journal of Biomedical Materials Research Part A", "publication_date": "2006-07", "series_number": "1", "volume": "78A", "issue": "1", "pages": "97-103" }, { "id": "authors:77xy9-gcm26", "collection": "authors", "collection_id": "77xy9-gcm26", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:PARapl06", "type": "article", "title": "Three-way electrical gating characteristics of metallic Y-junction carbon nanotubes", "author": [ { "family_name": "Park", "given_name": "J.", "clpid": "Park-J" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" }, { "family_name": "Bandaru", "given_name": "P. R.", "clpid": "Bandaru-P-R" }, { "family_name": "Gaillard", "given_name": "J.", "clpid": "Gaillard-J" }, { "family_name": "Rao", "given_name": "A. M.", "clpid": "Rao-A-M" } ], "abstract": "Y-junction based carbon nanotube (CNT) transistors exhibit interesting switching behaviors, and have the structural advantage that the electrical gate for current modulation can be formed by any of the three constituent branches. In this letter, we report on the gating characteristics of metallic Y-CNT morphologies. By measuring the output conductance and transconductance we conclude that the efficiency and gain depend on the branch diameter and is electric field controlled. Based on these principles, we propose a design for a Y-junction based CNT switching device, with tunable electrical properties.", "doi": "10.1063/1.2213013", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2006-06-12", "series_number": "24", "volume": "88", "issue": "24", "pages": "Art. No. 243113" }, { "id": "authors:0zrmm-a0056", "collection": "authors", "collection_id": "0zrmm-a0056", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-125859031", "type": "article", "title": "Synthesis of low-melting metal oxide and sulfide nanowires and nanobelts", "author": [ { "family_name": "Rao", "given_name": "R.", "clpid": "Rao-R" }, { "family_name": "Chandrasekaran", "given_name": "H.", "clpid": "Chandrasekaran-H" }, { "family_name": "Gubbala", "given_name": "S.", "clpid": "Gubbala-S" }, { "family_name": "Sunkara", "given_name": "M. K.", "clpid": "Sunkara-M-K" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" }, { "family_name": "Rao", "given_name": "A. M.", "clpid": "Rao-A-M" } ], "abstract": "The bulk nucleation and basal growth of semiconducting nanowires from molten Ga pools has been demonstrated earlier using oxygen/hydrogen plasma over molten Ga pools. Herein, we extend the above concept for bulk synthesis of oxide and sulfide nanowires of low-melting metal melts such as Sn and In. Specifically, nanowires of \u03b2-Ga_2O_3, \u03b2-In_2O_3, SnO_2, \u03b1-Ga_2S_3, and \u03b2-In_2S_3 were synthesized using direct reactions between respective molten metal pools and the gases such as oxygen/hydrogen mixture for oxides and H_2S for sulfides. In the case of \u03b2-Ga_2O_3 and SnO_2, a change in the morphology from nanowires to nanobelts was observed with an increase in the synthesis temperature. No such behavior was observed in the case of \u03b2-In_2O_3. Furthermore, we present evidence for \u03b1-Ga_2S_3 nanowires, which to our knowledge is being reported for the first time in the literature. Our studies with the sulfide nanowires suggest that H_2S reacts directly at the molten metal surface to form gallium sulfide. Finally, we discuss the role of chamber pressure and hydrogen on the size distribution of nanostructured \u03b2-Ga_2O_3 and SnO_2.", "doi": "10.1007/BF02692551", "issn": "0361-5235", "publisher": "Springer", "publication": "Journal of Electronic Materials", "publication_date": "2006-05", "series_number": "5", "volume": "35", "issue": "5", "pages": "941-946" }, { "id": "authors:dmvh0-ykr86", "collection": "authors", "collection_id": "dmvh0-ykr86", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:CHEapl06b", "type": "article", "title": "Extremely sharp carbon nanocone probes for atomic force microscopy imaging", "author": [ { "family_name": "Chen", "given_name": "I-Chen", "clpid": "Chen-I-Chen" }, { "family_name": "Chen", "given_name": "Li-Han", "clpid": "Chen-Li-Han" }, { "family_name": "Ye", "given_name": "Xiang-Rong", "clpid": "Ye-Xiang-Rong" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Jin", "given_name": "Sungho", "clpid": "Jin-Sungho" }, { "family_name": "Orme", "given_name": "Christine A.", "clpid": "Orme-C-A" }, { "family_name": "Quist", "given_name": "Arjan", "clpid": "Quist-A" }, { "family_name": "Lal", "given_name": "Ratnesh", "clpid": "Lal-R" } ], "abstract": "A simple and reliable catalyst patterning technique combined with electric-field-guided growth is utilized to synthesize a sharp and high-aspect-ratio carbon nanocone probe on a tipless cantilever for atomic force microscopy. A single carbon nanodot produced by an electron-beam-induced deposition serves as a convenient chemical etch mask for catalyst patterning, thus eliminating the need for complicated, resist-based, electron-beam lithography for a nanoprobe fabrication. A gradual, sputtering-induced size reduction and eventual removal of the catalyst particle at the probe tip during electric-field-guided growth creates a sharp probe with a tip radius of only a few nanometers. These fabrication processes are amenable for the wafer-scale synthesis of multiple probes. High resolution imaging of three-dimensional features and deep trenches, and mechanical durability enabling continuous operation for many hours without noticeable image deterioration have been demonstrated.", "doi": "10.1063/1.2193435", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2006-04-10", "series_number": "15", "volume": "88", "issue": "15", "pages": "Art. No. 153102" }, { "id": "authors:5nfhm-hdv09", "collection": "authors", "collection_id": "5nfhm-hdv09", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161003-143741677", "type": "article", "title": "Room Temperature Solvent-Free Synthesis of Monodisperse Magnetite Nanocrystals", "author": [ { "family_name": "Ye", "given_name": "X. R.", "clpid": "Ye-X-R" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Wang", "given_name": "C.", "clpid": "Wang-C" }, { "family_name": "Talbot", "given_name": "J. B.", "clpid": "Talbot-J-B" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" } ], "abstract": "We have successfully demonstrated a facile, solvent-free synthesis of highly crystalline and monodisperse Fe_3O_4 nanocrystallites at ambient temperature avoiding any heating. Solid state reaction of inorganic Fe(II) and Fe(III) salts with NaOH was found to produce highly crystalline Fe_3O_4 nanoparticles. The reaction, if carried out in the presence of surfactant such as oleic acid\u2013oleylamine adduct, generated monodisperse Fe_3O_4 nanocrystals extractable directly from the reaction mixture. The extracted nanoparticles were capable of forming self-assembled, two-dimensional and uniform periodic array. The new process utilizes inexpensive and nontoxic starting materials, and does not require a use of high boiling point and toxic solvents, thus is amenable to an environmentally desirable, large-scale synthesis of nanocrystals.", "doi": "10.1166/jnn.2006.135", "issn": "1533-4880", "publisher": "American Scientific Publishers", "publication": "Journal of Nanoscience and Nanotechnology", "publication_date": "2006-03", "series_number": "3", "volume": "6", "issue": "3", "pages": "852-856" }, { "id": "authors:dk6y3-z3q06", "collection": "authors", "collection_id": "dk6y3-z3q06", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DARprl06", "type": "article", "title": "Energy Trapping and Shock Disintegration in a Composite Granular Medium", "author": [ { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Nesterenko", "given_name": "V. F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Herbold", "given_name": "E. B.", "clpid": "Herbold-E-B" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" } ], "abstract": "We report the first experimental observation of impulse confinement and the disintegration of shock and solitary waves in one-dimensional strongly nonlinear composite granular materials. The chains consist of alternating ensembles of beads with high and low elastic moduli (more than 2 orders of magnitude difference) of different masses. The trapped energy is contained within the \"softer\" sections of the composite chain and is slowly released in the form of weak, separated pulses over an extended period of time. This effect is enhanced by using a specific group assembly and precompression.", "doi": "10.1103/PhysRevLett.96.058002", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2006-02-10", "series_number": "5", "volume": "96", "issue": "5", "pages": "Art. No. 058002" }, { "id": "authors:jz511-shw71", "collection": "authors", "collection_id": "jz511-shw71", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DARpre06b", "type": "article", "title": "Strongly nonlinear wave dynamics in a chain of polymer coated beads", "author": [ { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Nesterenko", "given_name": "V. F.", "clpid": "Nesterenko-V-F" } ], "abstract": "Strongly nonlinear phononic crystals were assembled from a chain of Parylene-C coated steel spheres in a polytetrafluoroethylene holder. This system exhibits strongly nonlinear properties and extends the range of materials supporting sonic-vacuum-type behavior. The combination of a high density core and a soft (low elastic modulus) coating ensures a relatively low velocity of wave propagation. The bead contact interaction caused by the deformation of the Parylene coating can be described by classical nonlinear elastic Hertz theory with an effective value of the elastic modulus equal to 15 GPa for the contact interaction. Strongly nonlinear solitary waves excited by impacts were investigated experimentally and compared to chains composed of uniform steel beads. Fracture of the polymer coating was detected under relatively large pulse amplitude.", "doi": "10.1103/PhysRevE.73.026612", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2006-02", "series_number": "2", "volume": "73", "issue": "2", "pages": "Art. No. 026612" }, { "id": "authors:3pm40-g2m73", "collection": "authors", "collection_id": "3pm40-g2m73", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DARpre06a", "type": "article", "title": "Tunability of solitary wave properties in one-dimensional strongly nonlinear phononic crystals", "author": [ { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Nesterenko", "given_name": "V. F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Herbold", "given_name": "E. B.", "clpid": "Herbold-E-B" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" } ], "abstract": "One-dimensional strongly nonlinear phononic crystals were assembled from chains of PTFE (polytetrafluoroethylene) and stainless-steel spheres with gauges installed inside the beads. Trains of strongly nonlinear solitary waves were excited by impacts. A significant modification of the signal shape and an increase of solitary wave speed up to two times (at the same magnitude of dynamic contact force) were achieved through a noncontact magnetically induced precompression of the chains. The data for the PTFE based chains are presented for the first time and the data for the stainless-steel beads chains are extended into a range of maximum dynamic forces more than one order of magnitude lower than previously reported. Experimental results agreed reasonably well with the long-wave approximation and numerical calculations based on the Hertz interaction law for particles interactions.", "doi": "10.1103/PhysRevE.73.026610", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2006-02", "series_number": "2", "volume": "73", "issue": "2", "pages": "Art. No. 026610" }, { "id": "authors:3cdsj-z6x35", "collection": "authors", "collection_id": "3cdsj-z6x35", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-132012368", "type": "article", "title": "Multibranching Carbon Nanotubes via Self-Seeded Catalysts", "author": [ { "family_name": "AuBuchon", "given_name": "Joseph F.", "clpid": "AuBuchon-J-F" }, { "family_name": "Chen", "given_name": "Li-Han", "clpid": "Chen-Li-Han" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Jin", "given_name": "Sungho", "clpid": "Jin-Sungho" } ], "abstract": "A novel multibranching carbon nanotube (CNT) structure is synthesized by direct current plasma enhanced chemical vapor deposition. The structure consists of aligned CNTs which have branches of smaller diameters growing aligned along a direction perpendicular to the original CNT. The mechanism of branching is explained in terms of a self-seeding of Ni catalyst which is transferred by sputtering from the original catalyst particles in the backbone CNTs to the walls of those CNTs. It is also shown that the branching induced a large increase in surface area and total nanotube length and can be beneficial in supporting very fine Pt nanoparticles for fuel cell and other catalytic applications. Such an array of Y-junction nanostructures could be useful for the fabrication of a high-density array of nanoelectronics switches and transistors.", "doi": "10.1021/nl052037t", "issn": "1530-6984", "publisher": "American Chemical Society", "publication": "Nano Letters", "publication_date": "2006-02", "series_number": "2", "volume": "6", "issue": "2", "pages": "324-328" }, { "id": "authors:vchsr-g3973", "collection": "authors", "collection_id": "vchsr-g3973", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:CHEapl06a", "type": "article", "title": "Growth of aligned carbon nanotubes on carbon microfibers by dc plasma-enhanced chemical vapor deposition", "author": [ { "family_name": "Chen", "given_name": "L.-H.", "clpid": "Chen-L-H" }, { "family_name": "AuBuchon", "given_name": "J. F.", "clpid": "AuBuchon-J-F" }, { "family_name": "Chen", "given_name": "I-C.", "clpid": "Chen-I-Chen" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Ye", "given_name": "X.-R.", "clpid": "Ye-Xiang-Rong" }, { "family_name": "Gapin", "given_name": "A.", "clpid": "Gapin-A" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" }, { "family_name": "Wang", "given_name": "C. M.", "clpid": "Wang-C-M" } ], "abstract": "It is shown that unidirectionally aligned carbon nanotubes can be grown on electrically conductive network of carbon microfibers via control of buffer layer material and applied electric field during dc plasma chemical vapor deposition growth. Ni catalyst deposition on carbon microfiber produces relatively poorly aligned nanotubes with significantly varying diameters and lengths obtained. The insertion of Ti 5 nm thick underlayer between Ni catalyst layer and C microfiber substrate significantly alters the morphology of nanotubes, resulting in much better aligned, finer diameter, and longer array of nanotubes. This beneficial effect is attributed to the reduced reaction between Ni and carbon paper, as well as prevention of plasma etching of carbon paper by inserting a Ti buffer layer. Such a unidirectionally aligned nanotube structure on an open-pore conductive substrate structure may conveniently be utilized as a high-surface-area base electrodes for fuel cells, batteries, and other electrochemical and catalytic reactions.", "doi": "10.1063/1.2166472", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2006-01-16", "series_number": "3", "volume": "88", "issue": "3", "pages": "Art. No. 033103" }, { "id": "authors:e1471-gcq92", "collection": "authors", "collection_id": "e1471-gcq92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161003-152846556", "type": "book_section", "title": "Electrical Transport in Carbon Nanotube Y-junctions- a Paradigm for Novel Functionality at the Nanoscale", "book_title": "Organic and inorganic nanotubes: from molecular to submicron structures", "author": [ { "family_name": "Park", "given_name": "Jeongwon", "clpid": "Park-Jeongwon" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Rao", "given_name": "Apparao", "clpid": "Rao-A-M" }, { "family_name": "Bandaru", "given_name": "Prabhakar", "clpid": "Bandaru-P" } ], "contributor": [ { "family_name": "Nielsch", "given_name": "K.", "clpid": "Nielsch-K" } ], "abstract": "Carbon Nanotube (CNT) morphologies with a self-contained gate, such as Y-junctions, offer a new way of exploiting features unique to the nanoscale, such as quantum ballistic transport. The advantages of low power and high frequency operation can then be applied to the fabrication of novel devices. Several other novel functionalities in Y- CNTs, including rectification, switching, high-frequency performance, and logic gates have been experimentally verified1. Y-CNT geometry dependent current blocking behavior, as a function of annealing temperature has also been observed. In view of the above observations, we propose that Y-CNTs can be used as prototypical nanoelectronic components.", "doi": "10.1557/PROC-0922-U11-08", "isbn": "9781558998797", "publisher": "Materials Research Society", "place_of_publication": "Warrendale, PA", "publication_date": "2006-01", "pages": "0922-U11" }, { "id": "authors:0vkgg-5xr75", "collection": "authors", "collection_id": "0vkgg-5xr75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-104532821", "type": "article", "title": "Iron Silicide Root Formation in Carbon Nanotubes Grown by Microwave PECVD", "author": [ { "family_name": "AuBuchon", "given_name": "Joseph F.", "clpid": "AuBuchon-J-F" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Chen", "given_name": "Li-Han", "clpid": "Chen-Li-Han" }, { "family_name": "Gapin", "given_name": "Andrew I.", "clpid": "Gapin-A-I" }, { "family_name": "Jin", "given_name": "Sungho", "clpid": "Jin-Sungho" } ], "abstract": "Aligned carbon nanotubes have been grown using microwave plasma enhanced chemical vapor deposition (PECVD). The carbon nanotubes are nucleated from iron catalyst particles which, during growth, remain adherent to the silicon substrates. By analysis with high-resolution electron microscopy, we observe iron silicide roots penetrating into the silicon substrate at the interface of the catalyst particles and the substrate, thus providing strong adhesion of the carbon nanotubes onto the substrate. The iron silicide roots assist in the attachment of the catalyst particles to the substrate and play a role in the evolution of the catalyst particle morphology and resulting base growth mode. Carbon nanotubes grown by microwave PECVD could exhibit superior electrical and thermal transport properties over other PECVD processes, so an understanding of the growth mechanism is important for utilization in device applications.", "doi": "10.1021/jp0558627", "issn": "1520-6106", "publisher": "American Chemical Society", "publication": "Journal of Physical Chemistry B", "publication_date": "2005-12-29", "series_number": "51", "volume": "109", "issue": "51", "pages": "24215-24219" }, { "id": "authors:h1az4-hnh16", "collection": "authors", "collection_id": "h1az4-hnh16", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:NESprl05", "type": "article", "title": "Anomalous Wave Reflection at the Interface of Two Strongly Nonlinear Granular Media", "author": [ { "family_name": "Nesterenko", "given_name": "V. F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Herbold", "given_name": "E. B.", "clpid": "Herbold-E-B" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" } ], "abstract": "Granular materials exhibit a strongly nonlinear behavior affecting the propagation of energy and information. Dynamically self-organized strongly nonlinear solitary waves are the main information carriers in granular chains. We report the first experimental observation of the dramatic change of solitary wave reflectivity from the interface of two granular media triggered by a magnetically induced precompression. It may be appropriate to name this phenomenon the \"acoustic diode\" effect. We explain this effect by the high gradient of particle velocity near the interface.", "doi": "10.1103/PhysRevLett.95.158702", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2005-10-07", "series_number": "15", "volume": "95", "issue": "15", "pages": "Art. No. 158702" }, { "id": "authors:g6fpw-2rv81", "collection": "authors", "collection_id": "g6fpw-2rv81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-154829375", "type": "article", "title": "Ultrastructural examination of dentin using focused ion-beam cross-sectioning and transmission electron microscopy", "author": [ { "family_name": "Nalla", "given_name": "R. K.", "clpid": "Nalla-R-K" }, { "family_name": "Porter", "given_name": "A. E.", "clpid": "Porter-A-E" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Minor", "given_name": "A. M.", "clpid": "Minor-A-M" }, { "family_name": "Radmilovic", "given_name": "V.", "clpid": "Radmilovic-V" }, { "family_name": "Stach", "given_name": "E. A.", "clpid": "Stach-E-A" }, { "family_name": "Tomsia", "given_name": "A. P.", "clpid": "Tomsia-A-P" }, { "family_name": "Ritchie", "given_name": "R. O.", "clpid": "Ritchie-R-O" } ], "abstract": "Focused ion-beam (FIB) milling is a commonly used technique for transmission electron microscopy (TEM) sample preparation of inorganic materials. In this study, we seek to evaluate the FIB as a TEM preparation tool for human dentin. Two particular problems involving dentin, a structural analog of bone that makes up the bulk of the human tooth, are examined. Firstly, the process of aging is studied through an investigation of the mineralization in 'transparent' dentin, which is formed naturally due to the filling up of dentinal tubules with large mineral crystals. Next, the process of fracture is examined to evaluate incipient events that occur at the collagen fiber level. For both these cases, FIB-milling was able to generate high-quality specimens that could be used for subsequent TEM examination. The changes in the mineralization suggested a simple mechanism of mineral 'dissolution and reprecipitation', while examination of the collagen revealed incipient damage in the form of voids within the collagen fibers. These studies help shed light on the process of aging and fracture of mineralized tissues and are useful steps in developing a framework for understanding such processes.", "doi": "10.1016/j.micron.2005.05.011", "issn": "0968-4328", "publisher": "Elsevier", "publication": "Micron", "publication_date": "2005-10", "series_number": "7-8", "volume": "36", "issue": "7-8", "pages": "672-680" }, { "id": "authors:mxbwz-6ze80", "collection": "authors", "collection_id": "mxbwz-6ze80", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-121730280", "type": "article", "title": "Novel electrical switching behaviour and logic in carbon nanotube Y-junctions", "author": [ { "family_name": "Bandaru", "given_name": "P. R.", "clpid": "Bandaru-P-R" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" }, { "family_name": "Rao", "given_name": "A. M.", "clpid": "Rao-A-M" } ], "abstract": "Carbon-nanotube-based electronics offers significant potential as a nanoscale alternative to silicon-based devices for molecular electronics technologies. Here, we show evidence for a dramatic electrical switching behaviour in a Y-junction carbon-nanotube morphology. We observe an abrupt modulation of the current from an on- to an off-state, presumably mediated by defects and the topology of the junction. The mutual interaction of the electron currents in the three branches of the Y-junction is shown to be the basis for a potentially new logic device. This is the first time that such switching and logic functionalities have been experimentally demonstrated in Y-junction nanotubes without the need for an external gate. A class of nanoelectronic architecture and functionality, which extends well beyond conventional field-effect transistor technologies, is now possible.", "doi": "10.1038/nmat1450", "issn": "1476-1122", "publisher": "Nature Publishing Group", "publication": "Nature Materials", "publication_date": "2005-09", "series_number": "9", "volume": "4", "issue": "9", "pages": "663-666" }, { "id": "authors:zfwca-nhh87", "collection": "authors", "collection_id": "zfwca-nhh87", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-101004335", "type": "article", "title": "Growth of nano-scale hydroxyapatite using chemically treated titanium oxide nanotubes", "author": [ { "family_name": "Oh", "given_name": "Seung-Han", "clpid": "Oh-Seung-Han" }, { "family_name": "Fino\u00f1es", "given_name": "Rita R.", "clpid": "Fino\u00f1es-R-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Chen", "given_name": "Li-Han", "clpid": "Chen-Li-Han" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" } ], "abstract": "A vertically aligned nanotube array of titanium oxide was fabricated on the surface of titanium substrate by anodization. The nanotubes were then treated with NaOH solution to make them bioactive, and to induce growth of hydroxyapatite (bone-like calcium phosphate) in a simulated body fluid. It is shown that the presence of TiO_2 nanotubes induces the growth of a \"nano-inspired nanostructure\", i.e., extremely fine-scale (\u223c8 nm feature) nanofibers of bioactive sodium titanate structure on the top edge of the \u223c15 nm thick nanotube wall. During the subsequent in-vitro immersion in a simulated body fluid, the nano-scale sodium titanate, in turn, induced the nucleation and growth nano-dimensioned hydroxyapatite (HAp) phase. The kinetics of HAp formation is significantly accelerated by the presence of the nanostructures. Such TiO_2 nanotube arrays and associated nanostructures can be useful as a well-adhered bioactive surface layer on Ti implant metals for orthopaedic and dental implants, as well as for photocatalysts and other sensor applications.", "doi": "10.1016/j.biomaterials.2005.01.048", "issn": "0142-9612", "publisher": "Elsevier", "publication": "Biomaterials", "publication_date": "2005-08", "series_number": "24", "volume": "26", "issue": "24", "pages": "4938-4943" }, { "id": "authors:86qsg-rqf96", "collection": "authors", "collection_id": "86qsg-rqf96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DARpre05", "type": "article", "title": "Strongly nonlinear waves in a chain of Teflon beads", "author": [ { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Nesterenko", "given_name": "V. F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Herbold", "given_name": "E. B.", "clpid": "Herbold-E-B" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" } ], "abstract": "One-dimensional \"sonic vacuum\" type phononic crystals were assembled from a chain of polytetrafluoroethylene (PTFE,Teflon) spheres with different diameters in a Teflon holder. It was demonstrated that this polymer-based sonic vacuum, with exceptionally low elastic modulus of particles, supports propagation of strongly nonlinear solitary waves with a very low speed. These solitary waves can be described using the classical nonlinear Hertz law despite the viscoelastic nature of the polymer and high strain rate deformation of the contact area. The experimentally measured speeds of solitary waves at high amplitudes are close to the theoretically estimated values with a Young's modulus of 1.46 GPa obtained from shock wave experiments. This is significantly higher than the Young's modulus of PTFE from ultrasonic measurements. Trains of strongly nonlinear solitary waves excited by an impact were investigated experimentally and were found to be in reasonable agreement with numerical calculations based on Hertz interaction law though exhibiting a significant dissipation.", "doi": "10.1103/PhysRevE.72.016603", "issn": "1539-3755", "publisher": "American Physical Society", "publication": "Physical Review E", "publication_date": "2005-07", "series_number": "1", "volume": "72", "issue": "1", "pages": "Art. No. 016603" }, { "id": "authors:46rt6-k9f14", "collection": "authors", "collection_id": "46rt6-k9f14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DARapl04", "type": "article", "title": "Highly nonlinear contact interaction and dynamic energy dissipation by forest of carbon nanotubes", "author": [ { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Nesterenko", "given_name": "Vitali F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Jin", "given_name": "Sungho", "clpid": "Jin-Sungho" } ], "abstract": "Mechanical response and energy dissipation of an array of carbon nanotubes under high-strain rate deformation was studied using a simple drop-ball test with the measurement of the dynamic force between the ball and forest of nanotubes. This convenient process allows extracting force\u2013displacement curves and evaluating dissipated energy by the nanotubes. The contact force exhibits a strongly nonlinear dependence on displacement being fundamentally different than the Hertz law. The forest of vertically aligned nanotubes may be used as a strongly nonlinear spring in discrete systems for monitoring signal propagation speed, and as a microstructure for localized energy absorption.", "doi": "10.1063/1.1829778", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2004-12-06", "series_number": "23", "volume": "85", "issue": "23", "pages": "5724-5726" }, { "id": "authors:4xm68-2xd88", "collection": "authors", "collection_id": "4xm68-2xd88", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:CHEapl04", "type": "article", "title": "Control of carbon nanotube morphology by change of applied bias field during growth", "author": [ { "family_name": "Chen", "given_name": "L.-H.", "clpid": "Chen-L-H" }, { "family_name": "AuBuchon", "given_name": "J. F.", "clpid": "AuBuchon-J-F" }, { "family_name": "Gapin", "given_name": "A.", "clpid": "Gapin-A" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Bandaru", "given_name": "P.", "clpid": "Bandaru-P-R" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" }, { "family_name": "Kim", "given_name": "D. W.", "clpid": "Kim-D-W" }, { "family_name": "Yoo", "given_name": "I. K.", "clpid": "Yoo-I-K" }, { "family_name": "Wang", "given_name": "C. M.", "clpid": "Wang-C-M" } ], "abstract": "Carbon nanotube morphology has been engineered via simple control of applied voltage during dc plasma chemical vapor deposition growth. Below a critical applied voltage, a nanotube configuration of vertically aligned tubes with a constant diameter is obtained. Above the critical voltage, a nanocone-type configuration is obtained. The strongly field-dependent transition in morphology is attributed primarily to the plasma etching and decrease in the size of nanotube-nucleating catalyst particles. A two-step control of applied voltage allows a creation of dual-structured nanotube morphology consisting of a broad base nanocone (~200 nm dia.) with a small diameter nanotube (~7 nm) vertically emanating from the apex of the nanocone, which may be useful for atomic force microscopy.", "doi": "10.1063/1.1830081", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2004-11-29", "series_number": "22", "volume": "85", "issue": "22", "pages": "5373-5375" }, { "id": "authors:tvsz7-e0d20", "collection": "authors", "collection_id": "tvsz7-e0d20", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-133008627", "type": "article", "title": "Rapid Prototyping of Site-Specific Nanocontacts by Electron and Ion Beam Assisted Direct-Write Nanolithography", "author": [ { "family_name": "Gopal", "given_name": "Vidyut", "clpid": "Gopal-V" }, { "family_name": "Radmilovic", "given_name": "Velimir R.", "clpid": "Radmilovic-V-R" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Jin", "given_name": "Sungho", "clpid": "Jin-Sungho" }, { "family_name": "Yang", "given_name": "Peidong", "orcid": "0000-0003-4799-1684", "clpid": "Yang-Peidong" }, { "family_name": "Stach", "given_name": "Eric A.", "clpid": "Stach-E-A" } ], "abstract": "Rapid prototyping of bottom-up nanostructure circuits is demonstrated, utilizing metal deposition and patterning methodology based on combined focused ion and electron beam induced decomposition of a metal\u2212organic precursor gas. Ohmic contacts were fabricated using electron beam deposition, followed by the faster process of ion beam deposition for interconnect formation. Two applications of this method are demonstrated:\u2009 three-terminal transport measurements of Y-junction carbon nanotubes and fabrication of nanocircuits for determination of electromechanical degradation of silver nanowires.", "doi": "10.1021/nl0492133", "issn": "1530-6984", "publisher": "American Chemical Society", "publication": "Nano Letters", "publication_date": "2004-11", "series_number": "11", "volume": "4", "issue": "11", "pages": "2059-2063" }, { "id": "authors:422rw-14n30", "collection": "authors", "collection_id": "422rw-14n30", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161003-144422760", "type": "article", "title": "Dynamic Nanofragmentation of Carbon Nanotubes", "author": [ { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Nesterenko", "given_name": "Vitali F.", "clpid": "Nesterenko-V-F" }, { "family_name": "Aubuchon", "given_name": "Joseph F.", "clpid": "Aubuchon-J-F" }, { "family_name": "Jin", "given_name": "Sungho", "clpid": "Jin-Sungho" } ], "abstract": "We report a new phenomenon of dynamic nanofragmentation of DC plasma grown carbon nanotubes under high-strain-rate conditions. An impacting sphere on vertically aligned multiwall nanotubes caused them to break up into short segments in just 15 microseconds with a relatively uniform length range of \u223c100\u2212150 nm. The ends of the fragmented nanotubes often exhibit an irregular oval or hexagonal cross-section. Some of the fragments show a sign of plastic bending near the fracture point. The mechanisms of multiple-breakup of nanotubes may be tentatively attributed to elastic buckling and fracture at the nodes or weak points, sequential fragmentation due to local bending, or contact interaction of crossed nanotubes. The observed cutting of nanotubes may conveniently be utilized for their resizing and end-opening for a variety of applications such as nanocomposite synthesis, nanoscale and large-surface-area reservoirs to store chemical reactants/catalysts, nanocarriers for therapeutic drugs/DNAs/proteins, and various other nanoelectronics and nanomechanics applications.", "doi": "10.1021/nl048946k", "issn": "1530-6984", "publisher": "American Chemical Society", "publication": "Nano Letters", "publication_date": "2004-10", "series_number": "10", "volume": "4", "issue": "10", "pages": "1915-1918" }, { "id": "authors:j3g03-dzy40", "collection": "authors", "collection_id": "j3g03-dzy40", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-130957245", "type": "article", "title": "Multiple Sharp Bendings of Carbon Nanotubes during Growth to Produce Zigzag Morphology", "author": [ { "family_name": "AuBuchon", "given_name": "Joseph F.", "clpid": "AuBuchon-J-F" }, { "family_name": "Chen", "given_name": "Li-Han", "clpid": "Chen-Li-Han" }, { "family_name": "Gapin", "given_name": "Andrew I.", "clpid": "Gapin-A-I" }, { "family_name": "Kim", "given_name": "Dong-Wook", "orcid": "0000-0002-5497-5853", "clpid": "Kim-Dong-Wook" }, { "family_name": "Daraio", "given_name": "Chiara", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Jin", "given_name": "Sungho", "clpid": "Jin-Sungho" } ], "abstract": "Carbon nanotubes have been grown with a sharply defined zigzag structure by introducing changes in the direction of applied electric field during dc plasma enhanced chemical vapor deposition (PECVD). The nanotubes maintain the same diameter before and after each bend while preserving the catalyst particle at the tip of growing nanotubes. The bends have very sharp radii of curvature of only \u223c25 nm. As a simple inclined field direction cannot produce such a zigzag growth due to the tendency of field lines intersecting perpendicular to the local surface, the bending has been introduced primarily by dramatically manipulating the electric field lines through controlled movement of field-concentrating conductor plates.", "doi": "10.1021/nl049121d", "issn": "1530-6984", "publisher": "American Chemical Society", "publication": "Nano Letters", "publication_date": "2004-09", "series_number": "9", "volume": "4", "issue": "9", "pages": "1781-1784" }, { "id": "authors:5cj65-fr528", "collection": "authors", "collection_id": "5cj65-fr528", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DARaipcp04", "type": "book_section", "title": "Strongly Nonlinear Waves in 3D Phononic Crystals", "book_title": "Shock compression of condensed matter--2003 : proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter held at Portland, Oregon, 20-25 July 2003", "author": [ { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Nesterenko", "given_name": "V.", "clpid": "Nesterenko-V-F" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" } ], "contributor": [ { "family_name": "Furnish", "given_name": "Michael D.", "clpid": "Furnish-M-D" }, { "family_name": "Gupta", "given_name": "Yogendra M.", "clpid": "Gupta-Y-M" }, { "family_name": "Forbes", "given_name": "Jerry W.", "clpid": "Forbes-J-W" } ], "abstract": "Three dimensional phononic crystal (\"sonic vacuum\" without prestress) was assembled from 137 vertical cavities arranged in hexagonal pattern in Silicone matrix filled with stainless steel spheres. This system has unique strongly nonlinear properties with respect to wave propagation inherited from nonlinear Hertz type elastic contact interaction. Trains of strongly nonlinear solitary waves excited by short duration impact were investigated. Solitary wave with speed below sound speed in the air and reflection from the boundary of two \"sonic vacuums\" were detected.", "doi": "10.1063/1.1780215", "isbn": "0-7354-0181-0", "publisher": "American Institute of Physics", "place_of_publication": "Melville, NY", "publication_date": "2004-07-20", "pages": "197-200" }, { "id": "authors:53tdy-xdm61", "collection": "authors", "collection_id": "53tdy-xdm61", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:SRIprb04", "type": "article", "title": "Vacancy-mediated mechanism of nitrogen substitution in carbon nanotubes", "author": [ { "family_name": "Srivastava", "given_name": "Deepak", "clpid": "Srivastava-D" }, { "family_name": "Menon", "given_name": "Maghu", "clpid": "Menon-M" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" }, { "family_name": "Sadanadan", "given_name": "Bindu", "clpid": "Sadanadan-B" }, { "family_name": "Rao", "given_name": "Apparao M.", "clpid": "Rao-A-M" } ], "abstract": "Nitrogen substitution reaction in a graphene sheet and carbon nanotubes of different diameter are investigated using the generalized tight-binding molecular dynamics method. The formation of a vacancy in curved graphene sheet or a carbon nanotube is found to cause a curvature dependent local reconstruction of the surface. Our simulations and analysis show that vacancy mediated N substitution (rather than N chemisorption) is favored on the surface of nanotubes with diameter larger than 8 nm. This predicted value of the critical minimum diameter for N incorporation is confirmed by experimental results presented on nitrogen-doped multiwalled nanotubes with [approximate]5 at. % nitrogen prepared by the thermal chemical vapor deposition process.", "doi": "10.1103/PhysRevB.69.153414", "issn": "0163-1829", "publisher": "American Physical Society", "publication": "Physical Review B", "publication_date": "2004-04-15", "series_number": "15", "volume": "69", "issue": "15", "pages": "Art. No. 153414" }, { "id": "authors:cwzrg-mf547", "collection": "authors", "collection_id": "cwzrg-mf547", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-090509158", "type": "article", "title": "Controlled Growth of Y-Junction Nanotubes Using Ti-Doped Vapor Catalyst", "author": [ { "family_name": "Gothard", "given_name": "N.", "clpid": "Gothard-N" }, { "family_name": "Daraio", "given_name": "C.", "orcid": "0000-0001-5296-4440", "clpid": "Daraio-C" }, { "family_name": "Gaillard", "given_name": "J.", "clpid": "Gaillard-J" }, { "family_name": "Zidan", "given_name": "R.", "clpid": "Zidan-Ragaiy" }, { "family_name": "Jin", "given_name": "S.", "clpid": "Jin-Sungho" }, { "family_name": "Rao", "given_name": "A. M.", "clpid": "Rao-A-M" } ], "abstract": "We demonstrate a bulk process for the synthesis of Y-junction carbon nanotubes using Ti-doped Fe catalysts. It is shown that the nanotube branching can be induced or stopped at will by tuning the Ti composition in the catalyst particle that seeds the growth of nanotubes. Detailed electron microscopic studies suggest that the mechanism for the observed Y-junction formation is mediated via catalyst particle attachment on the walls of a growing MWNT, from which the branching nanotubes nucleate and grow. By controlling the Ti concentration in the precursor, cascading Y-junction series as well as quadruple junctions have been successfully synthesized, offering the possibility for interesting device applications. The simplicity and controllability of such an in-situ Y-junction fabrication technique make it an excellent source of ready-made networks for potential nanoscale devices.", "doi": "10.1021/nl0349294", "issn": "1530-6984", "publisher": "American Chemical Society", "publication": "Nano Letters", "publication_date": "2004-02", "series_number": "2", "volume": "4", "issue": "2", "pages": "213-217" } ]