Modelling of sound damping multi-layers using a hybrid Finite Element - Wave Based Method

To assess and optimise the effect of multi-layered trim for the reduction of noise and vibration transmission, design engineers greatly depend on CAE tools. Mostly, these are based on element based simulation techniques such as the Finite Element Method (FEM). In practise, however, these methods are limited to low-frequency simulations due to the strongly increasing computational cost with frequency. They lose even more of their applicable frequency range when used for coupled acoustic-poro-elastic analysis. With the current simulation technologies, it is very challenging to solve a full FEM-model for the damped vibro-acoustic system into the mid-frequency domain. The Wave Based Method (WBM) is very well suited for this fullsystem modelling, since it has a very good convergence rate as compared to the FEM. On the other hand, the WBM shows its efficiency best for moderately complex geometries, where the domain can be divided into a (small) number of convex subdomains. To overcome this limitation, hybrid Finite Element Wave Based approaches have been developed and explored for coupling different physical media; acoustic, structural and structural-acoustic couplings can be tackled. This contribution extends this family of hybrid FE-WBM methods towards the coupling of acoustic WBM models with poro-elastic FEM models. In this way, the method benefits from the computational efficiency of the Wave Based Method for the acoustic calculations without losing the Finite Element Method’s ability to model the often layered and complexly shaped poroelastic materials in great detail.