Shear-mediated contributions to the effective properties of soft acoustic metamaterials including negative index.
Shear-mediated contributions to the effective properties of soft acoustic metamaterials including negative index.
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DOI：
10.1038/srep18562
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发表时间：
2015-12-21
影响因子：
4.6
通讯作者：
Pinfield VJ
中科院分区：
文献类型：
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作者：
Forrester DM;Pinfield VJ
在这里，我们表明，对于亚波长的流体中的颗粒，由于剪切波及其对相邻颗粒的影响的粘性损失显着修改的有效声学特性，从而发生负声折射的条件。早期的单粒子散射工作的基础上，我们采用了多重散射的方法来获得有效的属性（密度，体积模量，波数）。我们显示，通过理论预测，“软”（超声波）超材料的设计的基础上局部共振亚波长多孔橡胶颗粒的影响，通过选择颗粒的尺寸和浓度，并证明可调谐的负速度区通过修改悬浮介质的粘度。对于这些有损耗的材料与复杂的有效属性，我们确认使用的相位角来定义的反向传播条件，优先于“单”和“双负”的名称。
Here we show that, for sub-wavelength particles in a fluid, viscous losses due to shear waves and their influence on neighbouring particles significantly modify the effective acoustic properties, and thereby the conditions at which negative acoustic refraction occurs. Building upon earlier single particle scattering work, we adopt a multiple scattering approach to derive the effective properties (density, bulk modulus, wavenumber). We show,through theoretical prediction, the implications for the design of “soft” (ultrasonic) metamaterials based on locally-resonant sub-wavelength porous rubber particles, through selection of particle size and concentration, and demonstrate tunability of the negative speed zones by modifying the viscosity of the suspending medium. For these lossy materials with complex effective properties, we confirm the use of phase angles to define the backward propagation condition in preference to “single-” and “double-negative” designations.