Structural-acoustic mode synthesis for vehicle interior using finite-boundary elements with residual flexibility

A novel method of combining modal synthesis and residual flexibility for st ructure and boundary elements for fluid to compute the acoustic pressures i n an enclosed cavity that might have application in automotive industry is studied. Traditionally in the automotive industry, both the fluid cavity an d the enclosing flexible structure are modeled using finite elements to fin d the acoustic pressures. A method is proposed where the flexible structure s such as automotive panels are modeled using finite elements available in any commercial software package and fluid cavity is modeled using boundary elements. This approach substantially reduces modeling and computing effort required for fluid cavity. Modal synthesis and residual flexibility vector s to account for the truncated higher frequency modes of the flexible inter acting structure are utilized to improve the accuracy. Results of the new t echnique are compared against two other methods, namely direct frequency me thod and the case where both the structure and the fluid are modeled using finite elements.