Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session Y57: Mechanical Metamaterials III |
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Sponsoring Units: GSNP Chair: Martin van Hecke, AMOLF Room: BCEC 256 |
Friday, March 8, 2019 11:15AM - 11:27AM |
Y57.00001: Non-reciprocal Dynamic Response of a Bilinear Lattice Behrooz Yousefzadeh, Brian J Ramirez, Chiara Daraio We report on the non-reciprocal dynamics of a one-dimensional bilinear lattice subject to continuous harmonic excitation. The bilinear nature of the lattice is due to elements within the unit cell that have different elastic moduli in compression and extension. We investigate the asymmetric wave propagation characteristics of bilinear lattices, and explain the results based on the nonlinear dynamics of the unit cell. We show that we can obtain different responses for the forward and backward configurations relying on either (i) the harmonic (frequency-preserving) operating range, or (ii) different onsets of instability. We discuss experimental realization of the unit cell based on 3D-printed macroscale structures. |
Friday, March 8, 2019 11:27AM - 11:39AM |
Y57.00002: Anomalous Collisions of Elastic Vector Solitons in Mechanical Metamaterials Bolei Deng, Vincent Tournat, Pai Wang, Katia Bertoldi
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Friday, March 8, 2019 11:39AM - 11:51AM |
Y57.00003: Dynamics of nonlinear and localized vibrational modes in 2D mechanical networks Dominic Robe, Justin Burton Amorphous materials show surprising and potentially useful acoustic properties at low frequencies. A notable example are the low-temperature acoustic properties of dielectric glasses, where quasi-localized, resonant states absorb energy and form memories of past excitations. To probe these phenomena at low-frequencies and over long times, we study the vibrational modes of quasi-2D networks of coupled oscillators using parallelized, GPU computing. We vary the degree of pre-stretching (tension) in the network, disorder in site masses, and disorder in the network connectivity. Even with a crystalline network structure, disorder in the site masses gives rise to low-frequency, quasi-localized modes, similar to those studied in glasses and jammed systems. The anharmonic properties of these modes become exceedingly important over thousands of cycles of oscillations. In addition, in order to realize some of these properties in the laboratory, we have developed a mechanical metamaterial fabricated from a silicon nitride layer on a silicon wafer using standard photolithography. The degree and type of disorder can be tuned prior to fabrication, leading to a high-Q, constituent-level visualization of vibrational modes in disordered materials. |
Friday, March 8, 2019 11:51AM - 12:03PM |
Y57.00004: Solitons in one-dimensional mechanical linkage Koji Sato, Ryokichi Tanaka It has been shown by Kane and Lubensky that certain classical chains admit topologically protected zero-energy modes that are localized on the boundaries. Although the static features of the localized modes are well captured by linearized equations of motion, the description of their dynamics requires fully nonlinear treatment. We study quasi-periodic solutions of the nonlinear equations of motion of one-dimensional classical chains. Such quasi-periodic solutions correspond to periodic trajectories in the configuration space of the discrete systems, which allows us to define solitons without relying on a continuum theory. Furthermore, we study the dynamics of solitons in inhomogeneous systems by connecting two chains with distinct parameter sets, where solitons show intriguing transmission/reflection properties at the boundary of the two chains. |
Friday, March 8, 2019 12:03PM - 12:15PM |
Y57.00005: Topological phonons Sergio Leiva, Claudio Falcon, Alvaro S Nunez
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Friday, March 8, 2019 12:15PM - 12:27PM |
Y57.00006: Unidirectional transport in robotic mechanical metamaterials Martin Brandenbourger, Xander Locsin, Corentin Coulais Over the last few years, there has been an explosion of activity on non-reciprocal metamaterials, namely, which transmit motion in one direction, but block it in the other. However, to date, non-reciprocal transmission has only been achieved for a limited range of frequencies and input magnitudes |
Friday, March 8, 2019 12:27PM - 12:39PM |
Y57.00007: Thermally-triggered tunable vibration attenuation in 3D-printed mono-material lattice metamaterials Yangbo Li, Siyu Cao, Yan Shen Phononic crystals, capable to tailor mechanical wave propagation and displaying omnidirectional band gaps, are vital for numerous potential applications such as wave filtering, waveguiding, acoustic cloaking, and energy harvesting. In raw materials, vibration mitigation depending on intrinsic damping feature usually cannot be adjusted easily and broad attenuation frequency ranges is still scarce in these materials. Here, we propose a novel approach and metamaterial design with the ability of thermally-triggered tunable vibration mitigation in multiple frequency ranges, which arise from the local resonance mechanism. The proposed method utilizes reversible Young’s Modulus-temperature relationship of glassy polymer and non-uniformity of steady temperature field in solid structures. Through numerical simulations and low amplitude transmission testing, we demonstrate that the proposed method and metamaterials can exhibit broad and multiple omnidirectional band gaps. The finding reported here provides a new routine to design phononic metamaterial systems with tunable band gaps, offering a wide range of potential applications in harsh environmental conditions and being extended to baseline lattices with other topologies. |
Friday, March 8, 2019 12:39PM - 12:51PM |
Y57.00008: Electric-field-triggered instabilities in dielectric elastomer composites: application to tunable phononic crystals Michael Jandron, David Henann Tunable phononic crystals offer promising directions for elastic wave control. When phononic crystals are composed of soft dielectric elastomers, their band-gaps may be manipulated through an applied electric field. In addition, the rich electromechanical instability landscape in these materials offers opportunities for enhanced tunability. In this work, we report on our numerical simulation capability and show how electrically triggered instabilities provide a new route to tunability in phononic crystals composed of dielectric elastomers. The result is a comprehensive view of the instability landscape in dielectric elastomer composites, the suggestion of favorable actuation arrangements, as well a general strategy for exploring enhanced band-gap tunability. |
Friday, March 8, 2019 12:51PM - 1:03PM |
Y57.00009: Non-Abelian sound in mechanical metamaterials Michel Fruchart, Vincenzo Vitelli The propagation of mechanical waves in a medium is shaped by the microscopic arrangement of the oscillating elements. Here, we consider a material where the propagation of sound can be ruled by a band structure with a non-Abelian Berry connection stemming from the presence of an emerging non-crystallographic symmetry. This has dramatic consequences on the wave propagation inside an inhomogeneous medium and at interfaces. |
Friday, March 8, 2019 1:03PM - 1:15PM |
Y57.00010: Acoustic Bianisotropic Impedance and Hyperbolic Propagation in Metasurfaces Li Quan, Andrea Alu The strong analogies between electromagnetic and acoustic wave propagation have led to the discoveries of various forms of electromagnetic metamaterials and of their acoustic counterparts. However, the longitudinal properties of acoustics waves in fluid make the effective bulk modulus and effective impedance in acoustics inherently isotropic, which marks a strong difference, and a limitation of acoustic metamaterials and metasurfaces, compared to electromagnetics. Several important concepts in electromagnetics inherently require anisotropic impedance profiles, such as hyperbolic wave propagation, and therefore cannot find a direct counterpart in acoustics. Motivated by this limitation, in this talk we discuss a way to realize acoustic bianisotropy metasurfaces, relying on strong nonlocalities over the surface. Based on this approach, we introduce a design for hyperbolic acoustic metasurfaces with enhanced local density of states for sound, and inherent imaging and canalization properties. These design approaches based on strong nonlocality may also be extended to electromagnetics, offering a new path towards hyperbolic wave propagation. |
Friday, March 8, 2019 1:15PM - 1:27PM |
Y57.00011: Vortex Phase Singularities in Multiple Slit Interference Patterns in Chaotic Metamaterial Billiards Jorge Jose, Natalia M Litchinitser A wide range of diffractive wave interference patters have been produced by using different planar slit configurations. In particular, situations have been recently studied having more than two slits to test the validity of the superposition principle in wave and quantum mechanics. Here we study the presence of vortex or phase singular fluctuations produced by interference patterns in chaotic billiards with a variable number of diffraction slits. We report numerical wave simulation results of integrable and non-integrable D-shape billiards, having a variable number of slit type configurations. Embedded in this D-shaped chaotic billiards we considere different combinations of positive (PIM) and negative index of refraction (NIM) materials. We compare the topological charge in the phase singularities and their correlations in the different interference pattern configurations produced. We studied closed and open billiards. We found different types of topological charge properties directly related on the geometry, the number of slits as well as the different embedded PIM and NIM configurations. The properties of the vortex pattern configurations and their correlations change dramatically as a function of the geometry of the cavity and he number of slit configurations. |
Friday, March 8, 2019 1:27PM - 1:39PM |
Y57.00012: Liquid crystal elastomer based mechanical metamaterials for lightweight extreme impact energy absorption Seung-Yeol Jeon, Zeyu Zhu, Nicholas Traugutt, Cristina Martin Linares, Christopher Yakacki, Thao Nguyen, Sung Kang Liquid crystal elastomers (LCEs) are one of the most promising materials in the field of impact energy absorption, due to their exceptional energy dissipation behavior arising from the coupling of the relaxation dynamics of liquid crystal (LC) molecules and polymer chains. In this study, we report snapping-based metamaterials composed of LCEs for lightweight extreme impact energy absorption. We synthesized LCEs based on a two-stage thiol–acrylate reaction to program the order of LC molecules and chain alignment within beam elements. We characterized the energy absorption behaviors of the programmed LCE beams with bistability at various strain rates. We found that our LCE-based metamaterials show orders of magnitudes better specific energy absorption compared with previous works and their absorption capability is further enhanced as the strain rate increases. We could also tune the metastable energy states by controlling the strain rates. The combination of the inherent enhanced dissipation of LCEs with snapping-based architectures allows a new class of mechanical metamaterials with excellent energy absorbing capabilities. |
Friday, March 8, 2019 1:39PM - 1:51PM |
Y57.00013: Anisotropic Toughness and Crack Growth on Cubic SiC Fazle Elahi, Md Z Hossain Molecular dynamics calculation is executed applying the Stillinger-Weber atomic interaction to explore the anisotropic properties of cubic SiC.A solid 3C-SiC with predefined edge crack is subjected to uniaxial tensile load along its crystallographic axis. Three major directions (100), (110) and (111) are studied in this work.The crack propagation path is noticeably different in three directions which in return bring variation in critical energy absorption rate.In (100) plane toughness is 70% higher than in (111) plane.The reason behind this variation is the crack propagation path through the atomic system. In (100) direction, Crack starts growing at 7% strain when the stress is 21.9 GPa.The crack face atoms rather than bonds which hinder the growth and require more energy to break.The sole criterion for growth is bond breaking which drive the crack to branch out and propagate through (110) crystallographic plane. At the point of bifurcation, the solid absorb some energy which increase the fracture toughness.However, in other two planes, (111) and (110), crack sees no obstacle and bonds are parallel to the loading direction.They require lower critical energy release rate for crack growth.So, the crack evolve through the straight path and contain lower toughness. |
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