A finite element model for sound transmission through foam-lined double-panel structures

In this paper, methods for coupling both elastic porous material (i.e., foam) and structural finite elements with either modal or finite element representations of acoustical system are presented. In addition, interface conditions are described for coupling elastic porous material finite elements with acoustical and structural finite elements in various configurations. The foam finite element is based on the elastic porous material theory of Biot. By considering sound transmission through layered systems placed in a waveguide, the accuracy of the coupled acoustical-structural-foam finite element model has been verified by comparing its transmission loss predictions with analytical solutions for the matching cases of infinite lateral extent. The constraint conditions at the edges of both the foam lining and the facing panels were found to have a significant effect on the normal incidence sound transmission loss of the double panel system at low frequencies. (C) 1996 Acoustical Society of America.