scholarly journals Acoustic metamaterials: From local resonances to broad horizons

2016 ◽  
Vol 2 (2) ◽  
pp. e1501595 ◽  
Author(s):  
Guancong Ma ◽  
Ping Sheng
Keyword(s):  
Acoustic Wave ◽  
Mass Density ◽  
Constitutive Parameter ◽  
Acoustic Metamaterials ◽  
Resonant Structures ◽  
Wave Transport ◽  
Mechanical Metamaterials ◽  
Original Definition ◽  
Diverse Application ◽  
Recent Developments

Within a time span of 15 years, acoustic metamaterials have emerged from academic curiosity to become an active field driven by scientific discoveries and diverse application potentials. This review traces the development of acoustic metamaterials from the initial findings of mass density and bulk modulus frequency dispersions in locally resonant structures to the diverse functionalities afforded by the perspective of negative constitutive parameter values, and their implications for acoustic wave behaviors. We survey the more recent developments, which include compact phase manipulation structures, superabsorption, and actively controllable metamaterials as well as the new directions on acoustic wave transport in moving fluid, elastic, and mechanical metamaterials, graphene-inspired metamaterials, and structures whose characteristics are best delineated by non-Hermitian Hamiltonians. Many of the novel acoustic metamaterial structures have transcended the original definition of metamaterials as arising from the collective manifestations of constituent resonating units, but they continue to extend wave manipulation functionalities beyond those found in nature.

2d And 3d Acoustic Metamaterials Using Space Coil Design

2015 ◽  
Vol 1753 ◽  
Author(s):  
Santosh K. Maurya ◽  
Manu Sahay ◽  
Shobha Shukla ◽  
Sumit Saxena
Keyword(s):  
Acoustic Wave ◽  
Mass Density ◽  
3D Structure ◽  
Three Dimensional ◽  
Acoustic Metamaterials ◽  
Coil Design ◽  
Frequency Range ◽  
2D And 3D ◽  
Constitutive Parameters ◽  
Sub Wavelength

ABSTRACTVarious promising applications such as acoustic cloaking, sub-wavelength imaging, acoustic wave manipulation, transmission or reflection control etc. are feasible because of the ability of manipulating sounds and vibrations using artificially engineered “Acoustics meta-materials”. Recent works on space-coiling acoustic metamaterials show their extreme constitutive parameters like large refractive index, double negativity and zero mass density. Three dimensional structures have a wide application in sub-wavelength broadband acoustic wave suppression due to huge attenuation. Here we report the study of propagated and transmitted wave through 3D acoustic metamaterials structure using finite element method. Our simulations on 3D structure show a huge absorption/damping over few hundreds kilohertz frequency range.

scholarly journals Geometric charges and nonlinear elasticity of two-dimensional elastic metamaterials

2020 ◽  
Vol 117 (19) ◽  
pp. 10195-10202
Author(s):  
Yohai Bar-Sinai ◽  
Gabriele Librandi ◽  
Katia Bertoldi ◽  
Michael Moshe
Keyword(s):  
Elastic Problem ◽  
Porous Solids ◽  
Two Dimensional ◽  
Mechanical Instability ◽  
Mechanical Metamaterials ◽  
Recent Developments ◽  
Elastic Metamaterials ◽  
Geometrical Effects ◽  
Nonlinear Geometric ◽  
Geometric Formulation

Problems of flexible mechanical metamaterials, and highly deformable porous solids in general, are rich and complex due to their nonlinear mechanics and the presence of nontrivial geometrical effects. While numeric approaches are successful, analytic tools and conceptual frameworks are largely lacking. Using an analogy with electrostatics, and building on recent developments in a nonlinear geometric formulation of elasticity, we develop a formalism that maps the two-dimensional (2D) elastic problem into that of nonlinear interaction of elastic charges. This approach offers an intuitive conceptual framework, qualitatively explaining the linear response, the onset of mechanical instability, and aspects of the postinstability state. Apart from intuition, the formalism also quantitatively reproduces full numeric simulations of several prototypical 2D structures. Possible applications of the tools developed in this work for the study of ordered and disordered 2D porous elastic metamaterials are discussed.

scholarly journals Multi-physics adjoint modeling of Earth structure: combining gravimetric, seismic, and geodynamic inversions

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Georg S. Reuber ◽  
Frederik J. Simons
Keyword(s):  
Acoustic Wave ◽  
Mass Density ◽  
Resolving Power ◽  
Surface Velocity ◽  
Seismic Displacement ◽  
Material Parameters ◽  
Gradient Based ◽  
Geophysical Imaging ◽  
The Cost ◽  
Inversion Techniques

AbstractWe discuss the resolving power of three geophysical imaging and inversion techniques, and their combination, for the reconstruction of material parameters in the Earth’s subsurface. The governing equations are those of Newton and Poisson for gravitational problems, the acoustic wave equation under Hookean elasticity for seismology, and the geodynamics equations of Stokes for incompressible steady-state flow in the mantle. The observables are the gravitational potential, the seismic displacement, and the surface velocity, all measured at the surface. The inversion parameters of interest are the mass density, the acoustic wave speed, and the viscosity. These systems of partial differential equations and their adjoints were implemented in a single Python code using the finite-element library FeNICS. To investigate the shape of the cost functions, we present a grid search in the parameter space for three end-member geological settings: a falling block, a subduction zone, and a mantle plume. The performance of a gradient-based inversion for each single observable separately, and in combination, is presented. We furthermore investigate the performance of a shape-optimizing inverse method, when the material is known, and an inversion that inverts for the material parameters of an anomaly with known shape.

Dynamic mass density and acoustic metamaterials

2007 ◽  
Vol 394 (2) ◽  
pp. 256-261 ◽  
Author(s):  
Ping Sheng ◽  
Jun Mei ◽  
Zhengyou Liu ◽  
Weijia Wen
Keyword(s):  
Mass Density ◽  
Acoustic Metamaterials ◽  
Dynamic Mass

scholarly journals Two-Dimensional Composite Acoustic Metamaterials of Rectangular Unit Cell from Pentamode to Band Gap

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1457
Author(s):  
Qi Li ◽  
Ke Wu ◽  
Mingquan Zhang
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Band Gap ◽  
Unit Cell ◽  
The Other ◽  
Two Dimensional ◽  
Acoustic Metamaterials ◽  
Acoustic Wave Propagation ◽  
Theoretical Support ◽  
Unit Cells

Pentamode metamaterials have been receiving an increasing amount of interest due to their water-like properties. In this paper, a two-dimensional composite pentamode metamaterial of rectangular unit cell is proposed. The unit cells can be classified into two groups, one with uniform arms and the other with non-uniform arms. Phononic band structures of the unit cells were calculated to derive their properties. The unit cells can be pentamode metamaterials that permit acoustic wave travelling or have a total band gap that impedes acoustic wave propagation by varying the structures. The influences of geometric parameters and materials of the composed elements on the effective velocities and anisotropy were analyzed. The metamaterials can be used for acoustic wave control under water. Simulations of materials with different unit cells were conducted to verify the calculated properties of the unit cells. The research provides theoretical support for applications of the pentamode metamaterials.

scholarly journals A Composite Perforated Partitioned Sandwich Panel With Corrugation for Underwater Low-Frequency Sound Absorption

2021 ◽  
Vol 7 ◽  
Author(s):  
Junyi Wang ◽  
Jiaming Hu ◽  
Yun Chen
Keyword(s):  
Acoustic Wave ◽  
Composite Structure ◽  
Sound Absorption ◽  
Low Frequency ◽  
Propagation Loss ◽  
Sound Waves ◽  
Acoustic Metamaterials ◽  
Underwater Sound ◽  
Underwater Acoustic ◽  
Frequency Sound

Underwater acoustic wave absorption and control play an important role in underwater applications. Various types of underwater acoustic metamaterials have been proposed in recent years with the vigorous development of acoustic metamaterials. Compared with airborne sound, underwater sound waves have a longer wavelength and much smaller propagation loss, making them more difficult to control. In addition, given that the acoustic impedance of water is much greater than that of air, numerous conventional materials and structures are not suited to underwater use. In this paper, we propose a composite structure based on an excellent broadband low-frequency sound absorber of air using aluminum mixed with rubber. Our composite structure possesses broadband low-frequency (<1,000 Hz) sound absorption underwater, omnidirectional high sound absorption coefficient under the oblique incidence (0–75°), and pressure resistance. It has promising applications for underwater acoustic wave control and contributes to the design of underwater acoustic metamaterials.

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