Topology optimization for the radiation and scattering of sound from thin-body using genetic algorithms

Abstract

Many industrial applications generally use thin-body structures in their design. To calculate the radiation and scattering of sound from a thin-body structure, the conventional boundary element method (BEM) using the Helmholtz integral equation is not an effective resolution. Especially, if the structure including a thin-body is not fully closed, the conventional BEM fails to yield a reliable solution. Unfortunately, most applications requiring the noise prediction generally have some openings because of cooling and so on. Therefore, many researchers have studied to resolve the thin-body problem in various fields. In engineering optimization fields, even though several studies have been made on the design optimization to improve the acoustic characteristic of a closed structure by using the conventional BEM, no study has been yet reported for the design of the holes on the thin-body using topology optimization. In this research, the normal derivative integral equation is used to solve the acoustic problem of a thin-body structure. Also, based on the normal derivative integral equation, the topology optimization of the thin-body has been studied for the design of the holes. An in-house code, acTop, is developed and implemented for the acoustical topology optimization using a genetic algorithm. By using a simple box example, the utility of acTop is validated. The results of examples show that acTop can provide very good initial design for acoustic problems. Therefore, the proposed topology optimization technique should be attractive for a design engineer in acoustic fields.