Modelling of Transmission Loss for Trimmed Vehicle Components

In the automotive industry, the influence of poro-elastic components on acoustic comfort has been mostly investigated for airborne noise at mid- and high-frequency ranges. However, due to the lack of adequate theoretical formulations, the influence of poro-elastic in numerical vibro-acoustic simulation at lower frequency range has often been ignored or roughly approximated by the addition of distributed spring/mass on the BIW structure. Recent theoretical developments removed this limitation by providing an FEM formulation for poro-elastic material modelling. Using an FEM-only approach, this new theory was successfully used to compute the coupled vibro-acoustic response of a fully trimmed vehicle, which includes the BIW structure, the acoustic fluid and the poro-elastic materials (seats, carpet, dash insulator...). The latest development of powerful algorithms allows the automatic model setup and high-performance parallel calculation to be performed fast enough to be implemented into the sound package design process of large OEMs. Most recent developments allow the automatic Transmission Loss (TL) model-building process of complex components such as trimmed dash or floor. This paper presents a comparison between different types of cabin side dash insulators using the development described above and conpares these predictions with test.