基于材料选型的手性声学超材料带隙优化分析

Bandgap optimization for chiral acoustic metamaterials based on material selection method

[目的]旨在寻求扩大带隙频率范围,降低带隙起始频率的方法,分析并优化声学超材料的带隙。[方法]分析几何参数与材料参数对声学超材料带隙特性的影响,提出最大化带隙宽度方法。通过归一化带隙参数系数,将多目标优化问题转化为单目标优化问题。基于材料选型优化理论实现组分材料的转换,建立基于轻量化的手性声学超材料带隙参数优化方程。以六韧带手性声学超材料为例,定义散射体、韧带及包覆物等结构设计参数和材料参数为设计变量,开展声学超材料的结构参数-材料选型的综合优化。[结果]优化结果显示,带隙宽度增加了27.7%,下界频率减少了1048 Hz,初步达到了在声学超材料轻量化的基础上扩大带隙频率的目标;开展的有限长手性声学超材料结构的声传输分析验证了带隙优化方法的有效性。[结论]集成了结构参数-材料选型的综合优化可有效达到声学超材料轻量化的目标,研究成果可为新型声学超材料的设计提供技术参考。

[Objectives]This study seeks to expand the bandgap frequency band,reduce the bandgap starting frequency and analyze and optimize the bandgap parameters of acoustic metamaterials.[Methods]The influence of geometrical and material parameters on the bandgap properties of acoustic metamaterials is analyzed,and a method for maximizing the bandgap width is proposed.The multi-objective optimization problem is converted into a single objective optimization problem by normalizing the bandgap frequency coefficients.Structural material conversion is achieved via the material selection optimization method,and the optimization equations of bandgap parameters are established on the basis of weight-lightening.For chiral acoustic metamaterials,the material properties(density and wave velocity)and geometric parameters(scatterer diameter,ligament thickness and coating thickness)are defined as design variables,and the comprehensive optimization of structural parameters and material selection of acoustic metamaterials based on weight-lightening are implemented.[Results]The optimization results show that the bandgap width increases by 27.7% and the lower bound frequency decreases by 1048 Hz,thereby achieving the goal of expanding the bandgap width based on lightweight acoustic metamaterials.The acoustic transmission analysis of the finite chiral acoustic metamaterial structure is then carried out to verify the effectiveness of the proposed method.[Conclusions]The results show that the goal of lightweight acoustic metamaterials can be effectively achieved by integrating the comprehensive optimization of structural parameters and materials.As such,this study provides references for the design of new-type acoustic metamaterials.