A class of passive nonreciprocal acoustic metamaterials is developed to control the flow and distribution of acoustic energy in acoustic cavities and systems. Such development departs radically from present methods that favor the transmission direction by using hardwired arrangements of the hardware and hence, it cannot be reversed. The proposed nonreciprocal acoustic metamaterial (NAMM) cell consists of a cylindrical acoustic cavity with piezoelectric flexible boundaries that provide control in one-dimension. These boundaries are connected to an array of anti-parallel diodes to introduce simultaneous nonlinear damping and stiffness effects that break the reciprocity of energy flow through the NAMM cell. A finite element model of the NAMM cell is developed to investigate the nonreciprocal characteristics of the cell by optimizing the parameters that influence the nonlinear damping and stiffness effects introduced by the diodes. Numerical examples are presented to demonstrate the effectiveness of the proposed NAMM in tuning the directivity, flow, and distribution of acoustic energy propagating though the metamaterial.

中文翻译：

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具有反并联二极管的一维不可逆声学超材料的有限元建模。

开发了一类无源不可逆声学超材料，以控制声腔和系统中声能的流动和分布。这种发展与通过使用硬件的硬连线布置有利于传输方向的当前方法完全不同，因此不能逆转。提出的不可逆声学超材料（NAMM）单元由具有压电柔性边界的圆柱声腔组成，该压电声边界可提供一维控制。这些边界连接到反并联二极管阵列，以引入同时的非线性阻尼和刚度效应，从而破坏了流经NAMM电池的能量的互易性。通过优化影响二极管引入的非线性阻尼和刚度效应的参数，开发了NAMM单元的有限元模型以研究单元的不可逆特性。数值算例表明了拟议的NAMM在调节通过超材料传播的声能的方向性，流量和分布方面的有效性。