Optimization of sound transmission loss of open acoustic barriers with respect to unit cell topology

Abstract

Open acoustic barriers exhibit excellent sound transmission reduction property at a certain frequency/frequencies which highly depends on the configuration of its unit cell. Design of unit cell configuration for minimum sound transmission at predefined objective frequency remains an open question. This paper aims at providing an automatic design method for open acoustic barriers with multi-material unit cell. Firstly, a wave finite element method is developed to calculate the sound transmission through an infinite array of periodic scatterers. As the unit cell contains infinite fluid domain, the application of Floquet-Bloch theorem to the boundaries of perfectly match layers (PML) is necessary and has been resolved in this paper. This wave finite element method with the implementation of PML is validated by comparing to analytical solution of sound transmission through an array of steel cylinders. Then a genetic algorithm is employed to optimize the sound transmission loss with respect to material distribution of a bi-material unit cell. Finally, the effectiveness of this inverse design is demonstrated by examples with different predefined frequencies. Corresponding unit cell typologies are obtained and the dips of sound power transmission coefficient curve are successfully tuned to objective frequencies.

Analytical and numerical study on absorption of viscoelastic multilayers with variable cross section and cavity

“…The absorbing properties of such coatings may enhance with air cavities or solid particles 5,6 and is an interesting topic for topology optimization. 7 Consequently, analytical, numerical, and experimental studies on such coatings received much attention from researchers in the past decades and especially in recent years. Analytical studies usually utilize the transfer matrix method (TMM) to derive the relationship between the acoustic properties of the layers of the coating.…”

“…The absorbing properties of such coatings may enhance with air cavities or solid particles 5,6 and is an interesting topic for topology optimization. 7…”