A multilayer structured acoustic cloak with homogeneous isotropic materials

Cheng, Ying; Yang, Fan; Xu, Junyi; Liu, Xiao Jun

doi:10.1063/1.2903500

Cited by 224 publications

(144 citation statements)

References 16 publications

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“…Moreover, acoustic metamaterials with both negative effective bulk modulus and negative effective mass density have been proposed theoretically and experimentally [17][18][19][20][21]. Using the negative effective bulk modulus and the negative effective mass density, various pioneering and important applications such as acoustic cloaking [22][23][24][25][26][27][28][29][30][31][32], acoustic superlens and hyperlens [33][34][35][36][37][38][39][40][41][42], and acoustic black hole devices [43,44] have been proposed.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear dynamics of a model of acoustic metamaterials with local resonators

Higashiyama

Doi

Nakatani

2017

NOLTA

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Abstract:Nonlinear dynamics of a model of acoustic metamaterials with local resonators are investigated numerically and theoretically. We focus on dynamics of band edge modes (BEMs) and zone boundary modes (ZBMs) which are on the upper bounds of acoustic bands and optical bands of the phonon dispersion band. It is found that, in a region of weak anharmonicity, higher harmonics of a fundamental mode and static displacement are excited in both BEM and ZBM if the geometrical relation between the main lattice and the local resonators has evenorder nonlinearity. Numerical solutions of nonlinear periodic orbits which are continued from vibrations in the small amplitude limit by the shooting method indicate that structure of the periodic orbits of the local resonators depends on the form of nonlinear terms of the geometrical relation. Moreover, the nonlinear periodic orbits become unstable when the amplitude of the periodic orbit becomes larger. Direct numerical simulations show that unstable dynamics occur due to modulational instability. After destabilization of the nonlinear periodic orbits, spatial energy localization is also observed.

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Section: Introductionmentioning

confidence: 99%

Nonlinear dynamics of a model of acoustic metamaterials with local resonators

Higashiyama

Doi

Nakatani

2017

NOLTA

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“…The periodically layered structure can be used to guide sound waves as a transformational acoustic device through cutting a particular shape out of the periodic medium. Instead of the isotropic multilayer approach in constructing cylindrical cloaks [25] with the isotropic constitutive parameters varying in space, we consider only two types of constant materials: a solid and a fluid with constant material parameters and constant filling ratio. Let us begin with the planar solid plates, with volume filling fraction η in a fluid, stacking along the ydirection with a subwavelength lattice constant.…”

Section: Introductionmentioning

confidence: 99%

Bending a periodically layered structure for transformation acoustics

Liang

2011

Applied Physics Letters

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Anisotropic acoustic metamaterials have been proved very useful for their high potential in guiding and manipulating sound energy. In this paper, we further develop the idea by using periodically layered structures for transformational acoustics. Such a simple scheme periodically inserts identically bent solid plates in a background fluid. It forms a metamaterial with high refractive index normal to the curved plates and an index near to one along the plates. We show that the periodically layered structure, combined with transformation approach, can be cut into particular device shapes for acoustic cloaking and illusion. * Electronic address: jensen.li@cityu.edu.hk 1 Metamaterials are bringing new opportunities in manipulating electromagnetic, acoustic, and water waves, particularly through the framework of transformation optics [1][2][3][4][5][6][7][8][9][10]. In acoustics, we can design such metamaterials which consist of artificial periodic subwavelength structures to make their description using effective densities and moduli valid. Moreover, due to the engineering flexibility associated with these artificial materials, extreme values in their constitutive parameters can be obtained by using resonating subwavelength units [11][12][13][14]. Nevertheless, there is always a tradeoff between extreme constitutive parameters near resonance and a large working frequency bandwidth with low loss. It is therefore reasonable to investigate moderate acoustic metamaterials which can work in broadband with low loss. By introducing asymmetry in the shape of unit cells or in the constructing units, we can create acoustic metamaterials with broadband anisotropy [15,16].In particular, a one-dimensional lattice of alternating layers of a solid and a fluid has been found to possess large anisotropy. Such a simple periodically layered structure has been used to guide sound energy along the direction of fluid perforation for different applications. Acoustic superlenses, hyperlenses, acoustic devices with extraordinary transmission and recently an acoustic cavity have been fabricated utilizing this guiding capabilty of anisotropic acoustic metamaterials [17][18][19][20][21][22][23][24].In this work, we further extend the usage of such a simple periodically layered structure into the domain of transformation acoustics. In particular, we bend a periodic stack of planar solid plates with a percolating fluid. The periodically layered structure can be used to guide sound waves as a transformational acoustic device through cutting a particular shape out of the periodic medium. Instead of the isotropic multilayer approach in constructing cylindrical cloaks [25] with the isotropic constitutive parameters varying in space, we consider only two types of constant materials: a solid and a fluid with constant material parameters and constant filling ratio. Let us begin with the planar solid plates, with volume filling fraction η in a fluid, stacking along the ydirection with a subwavelength lattice constant. Such a metamaterial (with l...

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“…The most intriguing applications enabled by this methodology is cloak, which is capable of reducing the scattering and making an object undetectable. [2][3][4][5][6][7][8][9][10][11][12][13][20][21][22][23][24][25][26][27][28][29][30][31][32][33] The parameters of the ideal cloak are generally anisotropic, and they can also become isotropic under conformal mapping. 2 With the aid of artificial metamaterials, such cloaks have been experimentally demonstrated at microwave 7 and recently optical frequencies 8,9 in the EM wave field, and at ultrasound 30 and audio frequencies 31 in the acoustic wave field.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the invariance of the wave equation under coordinate transformations, this powerful conceptual design methodology has created a variety of unprecedented effects and functional devices by controlling the propagation paths of classic waves such as matter wave 1 , electromagnetic (EM) wave [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] and acoustic wave [20][21][22][23][24][25][26][27][28][29][30][31][32][33] at will. The most intriguing applications enabled by this methodology is cloak, which is capable of reducing the scattering and making an object undetectable.…”

Section: Introductionmentioning

confidence: 99%

Negative refraction induced acoustic concentrator and the effects of scattering cancellation, imaging, and mirage

2012

Self Cite

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We present a three-dimensional acoustic concentrator capable of significantly enhancing the sound intensity in the compressive region with scattering cancellation, imaging and mirage effects. The concentrator shell is built by isotropic gradient negative-index materials, which together with an exterior host medium slab constructs a pair of complementary medium. The enhancement factor, which can approach infinity by tuning the geometric parameters, is always much higher than that of traditional concentrator made by positive-index materials with the same size. The acoustic scattering theory is applied to derive the pressure field distribution of the concentrator, which is consistent with the numerical full-wave simulations. The inherent acoustic impedance match at the interfaces of the shell as well as the inverse processes of "negative refraction -progressive curvaturenegative refraction" for arbitrary sound rays can exactly cancel the scattering of the concentrator. Besides, the concentrator shell can also function as an acoustic spherical magnifying superlens, which produces perfect same-shaped image with bigger geometric and acoustic parameters located at a shifted position. Then some acoustic mirages are observed whereby the waves radiated from (scattered by) an object located in the center region may 2 seem to be radiated from (scattered by) its image. Based on the mirage effect, we further propose an intriguing acoustic transformer which can transform the sound scattering pattern of one object into another object at will with arbitrary geometric, acoustic and location parameters. 43.20.+g, 43.35.+d, 42.25.Fx PACS number(s):

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A multilayer structured acoustic cloak with homogeneous isotropic materials

Cited by 224 publications

References 16 publications

Nonlinear dynamics of a model of acoustic metamaterials with local resonators

Nonlinear dynamics of a model of acoustic metamaterials with local resonators

Bending a periodically layered structure for transformation acoustics

Negative refraction induced acoustic concentrator and the effects of scattering cancellation, imaging, and mirage

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