2 相材料モデルに基づく音響構造連成効果を考慮した音響メタサーフェスのトポロジー最適化

Abstract

This paper presents a level-set based topology optimization method for the design of an acoustic metasurface that can convert longitudinal acoustic waves into transverse elastic waves in an acoustic-elastic coupled system. We propose a two-phase material model in which the fluid and solid phases are mixed so that the model expresses the acoustic-elastic coupled system. A two-dimensional numerical example is provided and the amplitude of the transverse elastic waves is maximized by controlling the distribution of the acoustic waves. First, we explain the level set-based topology optimization method that guarantees the smoothness of the design boundaries. Next, the two-phase material model is proposed and the design problem for the wave motion-converting metasurface is formulated. Sensitivity analysis is conducted based on the concept of the topological derivative, and an optimization algorithm that uses the Finite Element Method for solving the wave propagation problem is developed. The numerical example demonstrates the validity of our optimization method.