Abstract
Sound absorbing poroelastic materials are widely used for noise reduction. One of the evaluation indexes indicating the performance of the sound absorbing material is a sound absorption coefficient. The sound absorption coefficient depends on the microscopic structure of the sound absorption material. At the moment it can calculate a sound absorption coefficient from microscopic structure, but it is difficult to design a sound absorbing material having a target sound absorption coefficient. In this research, we hope to design the microscopic structure of the sound absorbing material having the desired sound absorption coefficient and aid in material design. We express dynamic behavior of the sound absorbing material by Biot ’models, and microscopic structure assume a cubecell or a kelvincell. The flow resistance and characteristic length of a cubecell or a kelvincell are related to the unit cell size by the homogenization method. We use the unit cell size, the modulus of elasticity and the loss factor of the solid phase as design variables and search for a combination of values that minimizes the square residuals with the specified sound absorption coefficient by genetic algorithm (GA).We make microscopic structured model of provided unit cell size by the homogenization method inspected it. As a result, we were able to obtain an almost desired sound absorption coefficient.
