On the emergence of negative effective density and modulus in 2-phase phononic crystals

Mokhtari, Amir Ashkan; Lu, Yan; Srivastava, Ankit

doi:10.1016/j.jmps.2019.02.016

Cited by 34 publications

(9 citation statements)

References 48 publications

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“…Yang et al [67] studied a phononic focusing phenomenon in the passband over a complete band gap in a 3D phononic crystal and found that the wave propagation depends largely on the frequency and the direction of incidence, and due to the anisotropy of the propagation, very large negative refraction occurs. In 2019, Mokhtari et al [68] proposed the metamaterial properties of a two-phase unit cell traditionally considered to be a non-local resonance type, and demonstrated a hexagonal unit cell composed of two materials. They found that within the appropriate frequency range, the effective shear modulus and density are both negative and can produce negative refraction.…”

Section: Negative Refraction Effect Of Acoustic Waves [66]mentioning

confidence: 99%

A Review of Acoustic Metamaterials and Phononic Crystals

2020

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As a new kind of artificial material developed in recent decades, metamaterials exhibit novel performance and the promising application potentials in the field of practical engineering compared with the natural materials. Acoustic metamaterials and phononic crystals have some extraordinary physical properties, effective negative parameters, band gaps, negative refraction, etc., extending the acoustic properties of existing materials. The special physical properties have attracted the attention of researchers, and great progress has been made in engineering applications. This article summarizes the research on acoustic metamaterials and phononic crystals in recent decades, briefly introduces some representative studies, including equivalent acoustic parameters and extraordinary characteristics of metamaterials, explains acoustic metamaterial design methods, and summarizes the technical bottlenecks and application prospects.

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Section: Negative Refraction Effect Of Acoustic Waves [66]mentioning

confidence: 99%

A Review of Acoustic Metamaterials and Phononic Crystals

2020

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“…The solid is referred to as structured because it is made of a periodically repeating structure, or unit cell, whose characteristic dimensions are smaller than the dimensions of the solid itself. This scenario is common in the area of metamaterial design, where one is interested in obtaining non-conventional macroscopic elastodynamic properties for the solid, such as negative refractive index or negative effective density [61,62], by changing the geometric features and/or by coupling dissimilar materials at the scale the unit cell. Note that the aim of this section is not to provide an investigation of a structured solid in the context of metamaterials but to use the structured solid as an example of a (mildly) complex geometry where the elastodynamic problem can be solved with high-order accuracy in time and space by means of the present framework.…”

Section: Structured Solidsmentioning

confidence: 99%

Modelling wave propagation in elastic solids via high-order accurate implicit-mesh discontinuous Galerkin methods

Gulizzi,

Saye

2021

Preprint

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A high-order accurate implicit-mesh discontinuous Galerkin framework for wave propagation in single-phase and biphase solids is presented. The framework belongs to the embedded-boundary techniques and its novelty regards the spatial discretization, which enables boundary and interface conditions to be enforced with high-order accuracy on curved embedded geometries. High-order accuracy is achieved via high-order quadrature rules for implicitly-defined domains and boundaries, whilst a cell-merging strategy addresses the presence of small cut cells. The framework is used to discretize the governing equations of elastodynamics, written using a first-order hyperbolic momentum-strain formulation, and an exact Riemann solver is employed to compute the numerical flux at the interface between dissimilar materials with general anisotropic properties. The space-discretized equations are then advanced in time using explicit high-order Runge-Kutta algorithms. Several two-and three-dimensional numerical tests including dynamic adaptive mesh refinement are presented to demonstrate the high-order accuracy and the capability of the method in the elastodynamic analysis of single-and bi-phases solids containing complex geometries.

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“…On the way of solving the problem, it was preferred to use an arbitrary oriented acoustic plane wave and change the angle of wave in mathematical models and equations to show the change in relative status between the wave and the two sides of the sphere. The velocity potential function of incident wave field based on the partial wave expansion method [39][40][41] ,…”

Section: Acoustic Field Equationsmentioning

confidence: 99%

Acoustic steering of active spherical carriers

2020

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Following the novel introduced concept of the active carriers, this paper brings forward a technique toward the manipulability of an internally piezo-equipped active spherical carrier subjected to the progressive acoustic plane waves as the handling contactless asset. It is assumed that the piezoelectric part of the active carrier may be actuated as a bi-sectional body (i.e., two continuous hemispherical parts), with prescribed phase difference, and the polar position of the imaginary separating plane may be altered. This issue brings about an asymmetry in the dynamics of the problem which leads to emergence of position/frequency dependent acoustic radiation torque. It is obtained that as the carrier is excited by imposing harmonic voltage with the same amplitude and a π-radians phase difference, the zero-radiation force situation is obtained for a specific amplitude and phase of voltage as a function of frequency. This situation is treated as a criterion to determine the optimal amplitude of operation voltage. It is shown that the net force's direction exerted on the activated carrier may be steered along any desired orientation, assuming the fixed direction of incident wave field. The explained method of excitation and controllability of the spatial position of the divisor plane can possibly be a breakthrough in acoustic handling of active carriers. Noticeably, by this new technique, the single beam acoustic based contact-free methods and their applications in association with the concept of active carriers are now one step forward.

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On the emergence of negative effective density and modulus in 2-phase phononic crystals

Cited by 34 publications

References 48 publications

A Review of Acoustic Metamaterials and Phononic Crystals

A Review of Acoustic Metamaterials and Phononic Crystals

Modelling wave propagation in elastic solids via high-order accurate implicit-mesh discontinuous Galerkin methods

Acoustic steering of active spherical carriers

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