Faculty of Engineering, Ain Shams University, Cairo, 11517, Egypt.
J Acoust Soc Am. 2012 Oct;132(4):2857-65. doi: 10.1121/1.4744936.
Considerable interest has been devoted to the development of various classes of acoustic metamaterials that can control the propagation of acoustical wave energy throughout fluid domains. However, all the currently exerted efforts are focused on studying passive metamaterials with fixed material properties. In this paper, the emphasis is placed on the development of a class of composite one-dimensional acoustic metamaterials with effective densities that are programmed to adapt to any prescribed pattern along the metamaterial. The proposed acoustic metamaterial is composed of a periodic arrangement of cell structures, in which each cell consists of a circular sector cavity bounded by actively controlled flexible panels to provide the capability for manipulating the overall effective dynamic density. The theoretical analysis of this class of multilayered composite active acoustic metamaterials (CAAMM) is presented and the theoretical predictions are determined for a cascading array of fluid cavities coupled to flexible piezoelectric active boundaries forming the metamaterial domain with programmable dynamic density. The stiffness of the piezoelectric boundaries is electrically manipulated to control the overall density of the individual cells utilizing the strong coupling with the fluid domain and using direct acoustic pressure feedback. The interaction between the neighboring cells of the composite metamaterial is modeled using a lumped-parameter approach. Numerical examples are presented to demonstrate the performance characteristics of the proposed CAAMM and its potential for generating prescribed spatial and spectral patterns of density variation.
人们对各种类型的声波能量传播控制声学超材料的发展产生了浓厚的兴趣，这些声学超材料可应用于整个流体域。然而，目前所有的努力都集中在研究具有固定材料特性的被动超材料上。在本文中，重点研究了一类具有有效密度的复合一维声学超材料，其有效密度可根据超材料的任何规定图案进行编程。所提出的声学超材料由单元结构的周期性排列组成，其中每个单元由圆形扇形腔组成，由主动控制的柔性板包围，从而提供了操纵整体有效动态密度的能力。对这一类多层复合主动声学超材料（CAAMM）进行了理论分析，并对带有可编程动态密度的流体腔与柔性压电主动边界形成的级联阵列的 CAAMM 进行了理论预测。通过与流域的强耦合以及利用直接声压反馈，利用电来操纵压电边界的刚度，从而控制单个单元的整体密度。利用集中参数方法对复合超材料的相邻单元之间的相互作用进行建模。给出了数值示例，以演示所提出的 CAAMM 的性能特点及其产生规定的空间和频谱密度变化模式的潜力。
