Underwater acoustic omnidirectional absorber

Naify, Christina J.; Martin, Theodore P.; Layman, Christopher N.; Nicholas, Michael; Thangawng, Abel L.; Calvo, David; Orris, Gregory J.

doi:10.1063/1.4865480

Cited by 54 publications

(37 citation statements)

References 21 publications

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“…Traditional underwater and ultrasound applications have achieved an impedance match by utilizing rubbers that have sound speeds less than water. While rubbers are used as components in transparent metafluid lattices [1], there have been other recent advances in acoustic impedance-matched designs. For example, negative-index complementary metamaterials are proposed to significantly enhance the transparency through aberrating materials [30].…”

Section: Discussionmentioning

confidence: 99%

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Transparent Gradient-Index Lens for Underwater Sound Based on Phase Advance

et al. 2015

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Spatial gradients in a refractive index are used extensively in acoustic metamaterial applications to control wave propagation through phase delay. This study reports the design and experimental realization of an acoustic gradient-index lens using a sonic crystal lattice that is impedance matched to water over a broad bandwidth. In contrast to previous designs, the underlying lattice features refractive indices that are lower than the water background, which facilitates propagation control based on a phase advance as opposed to a delay. The index gradient is achieved by varying the filling fraction of hollow, air-filled aluminum tubes that individually exhibit a higher sound speed than water and matched impedance. Acoustic focusing is observed over a broad bandwidth of frequencies in the homogenization limit of the lattice, with intensity magnifications in excess of 7 dB. An anisotropic lattice design facilitates a flatfaceted geometry with low backscattering at 18 dB below the incident sound-pressure level. A threedimensional Rayleigh-Sommerfeld integration that accounts for the anisotropic refraction is used to accurately predict the experimentally measured focal patterns.

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Section: Discussionmentioning

confidence: 99%

“…GRIN geometries are utilized for a broad range of metamaterial applications including scattering reduction [6,7], wave focusing [8][9][10][11][12][13][14][15][16], and bending [1][2][3]17,18]. In contrast to previous lens designs, we present a lens composed of impedance-matched, hollow-shell elements with sound speeds higher than water.…”

Section: Introductionmentioning

confidence: 99%

Transparent Gradient-Index Lens for Underwater Sound Based on Phase Advance

et al. 2015

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“…1(a)]. In previous studies, 3,11,19,22,38 the inclusions of PCs are solid and the backgrounds are fluid. By contrast, the backgrounds of the present CGPCs are solid and the inclusions are fluid, and these CGPCs are porous cylinders with continuously graded structures.…”

Section: Methodsmentioning

confidence: 99%

“…34 Several studies have been devoted to the sound absorption characteristics of PCs, and have indicated that PCs could be employed to expand the content of sound absorption materials. [35][36][37][38] To the best knowledge of the authors, no research has been conducted on the sound absorption characteristics of CGPCs.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the sound absorption characteristics of continuously graded phononic crystals

Zhang

et al. 2016

AIP Advances

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Novel three-dimensional (3D) continuously graded phononic crystals (CGPCs) have been designed, and fabricated by 3D printing. Each of the CGPCs is an entity instead of a combination of several other samples, and the porosity distribution of the CGPC along the incident direction is nearly linear. The sound absorption characteristics of CGPCs were experimentally investigated and compared with those of uniform phononic crystals (UPCs) and discretely stepped phononic crystals (DSPCs). Experimental results show that CGPCs demonstrate excellent sound absorption performance because of their continuously graded structures. CGPCs have higher sound absorption coefficients in the large frequency range and more sound absorption coefficient peaks in a specific frequency range than UPCs and DSPCs. In particular, the sound absorption coefficients of the CGPC with a porosity of 0.6 and thickness of 30 mm are higher than 0.56 when the frequency is 1350–6300 Hz and are all higher than 0.2 in the studied frequency range (1000–6300 Hz). CGPCs are expected to have potential application in noise control, especially in the broad frequency and low-frequency ranges.

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“…[4][5][6] It has now evolved into a powerful tool for designing a wide variety of new devices. [7][8][9][10][11][12] The most remarkable example is the invisibility cloak which has attracted great attention from researchers. [13][14][15] The acoustic invisibility cloak can make objects hard to detect acoustically.…”

Section: Introductionmentioning

confidence: 99%

Design and analysis of the trapeziform and flat acoustic cloaks with controllable invisibility performance in a quasi-space

et al. 2015

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We present the design, implementation and detailed performance analysis for a class of trapeziform and flat acoustic cloaks. An effective large invisible area is obtained compared with the traditional carpet cloak. The cloaks are realized with homogeneous metamaterials which are made of periodic arrangements of subwavelength unit cells composed of steel embedded in air. The microstructures and its effective parameters of the cloaks are determined quickly and precisely in a broadband frequency range by using the effective medium theory and the proposed parameters optimization method. The invisibility capability of the cloaks can be controlled by the variation of the key design parameters and scale factor which are proved to have more influence on the performance in the near field than that in the far field. Different designs are suitable for different application situations. Good cloaking performance demonstrates that such a device can be physically realized with natural materials which will greatly promote the real applications of invisibility cloak.

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Underwater acoustic omnidirectional absorber

Cited by 54 publications

References 21 publications

Transparent Gradient-Index Lens for Underwater Sound Based on Phase Advance

Transparent Gradient-Index Lens for Underwater Sound Based on Phase Advance

Experimental study on the sound absorption characteristics of continuously graded phononic crystals

Design and analysis of the trapeziform and flat acoustic cloaks with controllable invisibility performance in a quasi-space

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