Sizing optimization of microstructure of sound-absorbing poroelastic material by homogenization method

Acoustic properties of sound-absorbing poroelastic media such as sound absorption coefficient are affected by microscopic structures. However, the design method for microscopic structures of sound-absorbing poroelastic media has not been established and the trial and error approach based on prototypes is required. In this study, a parametric optimization method to design microscopic structures of sound-absorbing poroelastic media is proposed. First, various models of microscopic structure of sound-absorbing material are generated by some sets of microscopic parameters and homogenized macroscopic properties, such as air flow resistivity and equivalent density and bulk modulus, are calculated by the homogenization method. Then, Biot’s parameters are identified for each microscopic structure of sound-absorbing poroelastic material by using non-linear least square method, and the functions that link between Biot’s parameters and the microscopic parameters, such as fiber diameter and pore radius, are derived. Finally, the microscopic parameters of poroelastic materials are optimized by using genetic algorithm (GA) to maximize sound absorption coefficient at prescribed target frequencies. In the verification of the proposed design method, the microscopic structures of fibrous porous material and foamed poroelastic material are optimized.