Design Optimization for Structural-Acoustic Problems Using FEM-BEM

A structural-acoustic design optimization of a vehicle is presented using finite element and boundary element analyses. The steady-state dynamic behavior of the vehicle is calculated from the finite element frequency response analysis, while the sound pressure level within the acoustic cavity is calculated using the boundary element analysis. A reverse solution procedure is employed for the design sensitivity calculation using the adjoint variable method. An adjoint load is obtained from the acoustic boundary element re-analysis, while the adjoint solution is calculated from the structural dynamic re-analysis. The evaluation of pressure sensitivity only involves a numerical integration process for the structural part. Two design optimization problems are formulated and solved. It has been shown that the structural weight is saved when the noise level is maintained, and the weight needs to increase in order to reduce the noise level in the passenger compartment.