Design of direction of propagation control structure for broadband sound wave using topology optimization

Abstract

By placing special periodic structures called acoustic metamaterials or acoustic metasurfaces in the sound propagation path, it is possible to control the acoustic properties. However, the shape of the periodic structure with the desired acoustic properties is complex and not easy to design. In this study, a topology optimization method using the level set method is used to design a structure that guides sound waves propagating parallel to a flat wall into a specific space. A structure with better acoustic properties than the aperiodic structure was obtained. The obtained structure has multiple projection shapes, and it was confirmed that the direction of travel can be controlled for sound waves with a wide range of frequencies.