A comparison of analytical and optimization inverse techniques for characterizing intrinsic parameters of porous materials.

Abstract

In recent years, sound absorbing materials are finding many applications in transport industry. In automobiles, they are used as noise control treatments in engine compartment as well as in passenger cabin. To understand and simulate acoustic behavior of these noise control treatments, intrinsic physical parameters are required. The acoustical behavior of poroelastic material is governed by five macroscopic intrinsic parameters, e.g., porosity, flow resistivity, tortuosity, and characteristics lengths as well as three mechanical parameters. Out of these five physical parameters, porosity and flow resistivity can be measured directly by available standardized methods. But measurement of physical parameters such as tortuosity, viscous, and thermal characteristic lengths is very difficult and no accepted procedure is available for their measurement. As an alternative, analytical inverse approach (mid‐frequency) and optimization technique Genetic algorithm are well known in the literature. This paper compares the results from both techniques for intrinsic parameters. It also presents the effect of inverted parameters on sound absorption and transmission loss of the porous materials using Johnson–Champoux–Allard model.