A fast vibro-acoustic response analysis method for double wall structures including a viscothermal air layer

The damping behaviour of a thin air layer between two flexible panels can be used to reduce sound radiation of structural excited panels. The numerical model of the double wall panels takes into account full acousto-elastic interaction and viscothermal wave propagation in the air layer. This means that the resulting system matrices are complex and frequency dependent which makes it difficult to perform response calculations. In this paper a very efficient calculation method is presented which is based on the superposition of uncoupled structural and acoustic eigenmodes. The frequency dependent behaviour is implemented by updating the reduced acoustic submatrices for each frequency step. The method is successfully implemented in the B2000 processor B2FRF