五模声学超表面分段设计及其波控性能分析

Piecewise design for pentamode acoustic metasurface and analysis of its wave manipulation performance

为拓宽五模微结构可实现的等效物性参数范围,提出采用两种基材对超表面分段设计的方法.在五模超表面理论推导的基础上,以Norris提出的微结构为基本构型,采用均匀化理论计算微结构的等效模量矩阵,对微结构几何参数进行优化设计,获得了具有铝和钛合金两段基材的反射式声学超表面.结合能带分析和定向反射仿真实验,分析了微结构声学特性及其对超表面波控性能的影响,仿真结果表明:具有两种基材的超表面能够实现较宽的模量和密度分布,从而保证所需声速梯度,仿真结果验证了方法的可行性和有效性.本方法为五模超材料设计提供了一种新途径,对于大空间或大角度的声波调控具有重要的工程应用价值.

To broaden the ranges of realizable effective properties of pentamode metamaterial,a piecewise design method using two kinds of matrix materials for the metasurface was proposed.Based on the theory derivations of pentamode metamaterial,homogenization theory was utilized to calculate equivalent modulus matrix of microstructures proposed by Norris and to design the microstructures geometric parameters,and an acoustic reflective metasurface with two pieces of matrix materials of aluminum and titanium alloy was obtained.Combining the band structures analysis with directional reflection simulations,the acoustic properties of microstructures and their effects on the wave manipulation performance were analyzed.Simulation results show that the metasurface with two matrix materials can achieve the required distribution of effective modulus and density to ensure the sound velocity gradient,and the results verify the feasibility and effectiveness of the method.This method provides a new approach for the pentamode metamaterial design,and has important engineering application values for large spaces or large angles wave manipulations.