Investigation of Topology Optimization for Suppressing Floating Structures in Acoustic Device Design

Abstract

In our living environment, various noise reduction techniques exist, utilizing acoustic devices with functions such as sound absorption and sound insulation to mitigate unwanted sounds. Recently, acoustic metamaterial and acoustic metasurface, which offer capabilities beyond conventional structures, have garnered significant research interest. Due to the complex geometries of these advanced acoustic devices, designing them through trial and error is challenging. Consequently, topology optimization, which provides the highest degree of design freedom among optimization methods, has been proposed for their design. However, structures designed via topology optimization often contain floating elements that are impractical to implement. This study proposes a novel method to address this issue by applying an external force to the structures during optimization and imposing an upper limit constraint on their displacement. This constraint prevents the generation of floating structures, which exhibit larger displacements than those supported by fixed boundaries. The effectiveness of the proposed method is demonstrated through its application to the design of acoustic diodes, which allow sound to propagate in one direction while blocking it in the opposite direction. The results confirm the viability and effectiveness of the proposed approach, providing practical insights for the design of advanced acoustic devices.