Numerical prediction of sound transmission through finite multilayer systems with poroelastic materials

The sound transmission performance of finite multilayer systems containing poroelastic materials is of utmost importance for noise control in automobiles, aircrafts, buildings, and several other engineering applications. Currently, the need for tools predicting the acoustical and structural behaviors of such structures is considerably increasing. In this paper, such a tool is presented. It is applied to the sound transmission loss through multilayer structures made from a combination of elastic, air, and poroelastic materials. The presented approach is based on a three-dimensional finite element model. It uses classical elastic and fluid elements to model the elastic and fluid media. For the poroelastic material, it uses a two-field displacement formulation derived from the Blot theory. Furthermore, it couples with a boundary element approach to account, when important, for fluid-structure coupling and to calculate the transmission loss through the multilayer structure. Numerical predictions of the transmission loss through a poroelastic material sandwiched between two finite elastic plates are presented for various configurations. It is shown that the unbonded/bonded configuration gives better transmission loss. Also, comparisons with laterally infinite double panels and with an equivalent fluid approach for the porous material are presented. It is shown that these two simplified models lead to erroneous predictions at low frequencies and for certain design configurations, respectively. (C) 1996 Acoustical Society of America.