One path to acoustic cloaking
Steven A. Cummer,David Schurig +1 more
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TLDR
In this paper, it was shown that the acoustic equations in a fluid are identical in form to the single polarization Maxwell equations via a variable exchange that also preserves boundary conditions, and the existence of transformation-type solutions for the 2D acoustic equations with anisotropic mass via time harmonic simulations of acoustic cloaking.Abstract:
A complete analysis of coordinate transformations in elastic media by Milton et al has shown that, in general, the equations of motion are not form invariant and thus do not admit transformation-type solutions of the type discovered by Pendry et al for electromagnetics. However, in a two-dimensional (2D) geometry, the acoustic equations in a fluid are identical in form to the single polarization Maxwell equations via a variable exchange that also preserves boundary conditions. We confirm the existence of transformation-type solutions for the 2D acoustic equations with anisotropic mass via time harmonic simulations of acoustic cloaking. We discuss the possibilities of experimentally demonstrating acoustic cloaking and analyse why this special equivalence of acoustics and electromagnetics occurs only in 2D.read more
Citations
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Special transformations for pentamode acoustic cloaking
TL;DR: In this article, the authors inverted the conventional cloaking process by defining desirable material properties and then deriving the appropriate transformations which guarantee the cloaking effect, resulting in acoustic cloaks with special properties such as constant density, constant radial stiffness, and minimal elastic anisotropy.
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From Photonic Crystals to Seismic Metamaterials: A Review via Phononic Crystals and Acoustic Metamaterials
TL;DR: In this paper, the authors discuss the historical context, current progresses and possible future outcomes of metamaterials and highlight the interesting phenomena observed in optics/electromagnetic metammaterials with acoustic and elastic counterparts.
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Acoustic cloaking transformations from attainable material properties
TL;DR: In this article, the authors proposed a general methodology and a set of practical recipes for the construction of ultra-broadband acoustic cloaks, which can render themselves and a concealed object undetectable by means of acoustic scattering.
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Acoustic performance of gratings of cylindrical voids in a soft elastic medium with a steel backing.
TL;DR: An approximate analytical model is presented to investigate sound transmission, reflection and absorption of a rubber-like medium comprising a single layer of periodic cylindrical voids attached to a steel backing, modelled as a homogeneous medium with effective material and geometric properties.
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Employing pre-stress to generate finite cloaks for antiplane elastic waves
TL;DR: In this article, it was shown that nonlinear elastic pre-stress of hyperelastic materials can be used as a mechanism to generate finite cloaks and render objects near-invisible to incoming antiplane elastic waves.
References
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TL;DR: In this paper, it was shown that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability /spl mu/sub eff/, which can be tuned to values not accessible in naturally occurring materials.
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Controlling Electromagnetic Fields
TL;DR: This work shows how electromagnetic fields can be redirected at will and proposes a design strategy that has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields.
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Metamaterial Electromagnetic Cloak at Microwave Frequencies
David Schurig,Jack J. Mock,B.J. Justice,Steven A. Cummer,John B. Pendry,Anthony F. Starr,David R. Smith +6 more
TL;DR: This work describes here the first practical realization of a cloak of invisibility, constructed with the use of artificially structured metamaterials, designed for operation over a band of microwave frequencies.
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Optical Conformal Mapping
TL;DR: A general recipe for the design of media that create perfect invisibility within the accuracy of geometrical optics is developed, which can be applied to escape detection by other electromagnetic waves or sound.
Journal ArticleDOI
Ultrasonic metamaterials with negative modulus
Nicholas X. Fang,Dongjuan Xi,Jianyi Xu,Muralidhar Ambati,Werayut Srituravanich,Cheng Sun,Xiang Zhang +6 more
TL;DR: A new class of ultrasonic metamaterials consisting of an array of subwavelength Helmholtz resonators with designed acoustic inductance and capacitance with an effective dynamic modulus with negative values near the resonance frequency is reported.