Since the last decade, the automotive industry has expressed the need to better understand how the different trim parts interact together in a complete car up to 400 Hz for structureborne excitations. Classical FE methods in which the acoustic trim is represented as non-structural masses (NSM) and high damping or surface absorbers on the acoustic cavity can only be used at lower frequencies and do not provide insights into the interactions of the acoustic trims with the structure and the acoustic volume. It was demonstrated in several papers that modelling the acoustic components using the poroelastic finite element method (PEM) can yield accurate vibro-acoustic response such as transmission loss of a car component [1,2,3]. The increase of performance of today's computers and the further optimization of commercial simulation codes allow computations on full vehicle level [4,5,6] with adequate accuracy and computation times, which is essential for a car OEM.
This paper presents a study of a fully trimmed vehicle excited by structureborne excitations with almost all acoustic trims such as seats, dash insulator, instrument panel, headliner… which are modelled as poroelastic finite element (PEM) parts. Simulation results are compared with extensive measurement results. The interactions between structure, acoustic trims and acoustic volume are illustrated and finally the analysis of several design changes such as trim material properties or geometry modifications is demonstrated.