高周波均質化法に基づく伝搬方向規定を用いた異方性音響メタマテリアルのマルチスケールトポロジー最適化設計法

抄録

In this research, we propose a multi-scale design method of anisotropic acoustic metamaterials based on propagating direction determination. Anisotropic metamaterials are usually composed of periodic structures of unit cells. These periodic structures tend to induce local resonance, leading to a highly unusual macroscopic behavior. In previous works, design methods for anisotropic metamaterials comprised of only a single unit cell structure were proposed, which means that the macro-scale wave propagation properties which could be obtained are limited. Therefore, in this work, we propose a design method of acoustic metamaterials which is composed of several unit cell structures, to realize a complex wave propagation. To evaluate the macroscopic material property of periodic media, we first introduce the high-frequency homogenization (HFH) method. We also evaluate the macroscopic wave propagating direction derived from the HFH method, which is required to control the macro-scale wave propagation. We then design the micro-scale unit cells which exbibits the desired propagating direction, using the level-set based topology optimization method. The validity of the proposed method is verified through numerical examples.