Trim FEM simulation of a complete seat structure with foam cushions under structureborne and airborne excitations

摘要

Usually in the automotive industry, when analysing the vibro-acoustic properties of a completeseat, the dynamical behavior of the seat metal frame and the absorption properties of the seatcushions are considered separately. In fact, both are interacting when exciting the trimmed seatstructure with structureborne noise and observing the resulting Sound Pressure Level in acoupled cavity. Besides the absorption properties of the foam cushions, the induced damping tothe seat structure due to the poroelastic properties of the foam are quite significantexperimentally. The goal of this study has been to simulate the aforementioned phenomena andespecially the fully coupled vibro-acoustic response of a complete seat structure with foamcushions coupled to a concrete cavity using poroelastic finite elements (u-p formulation) up to600 Hz.The first step has been to correlate the bare finite element model of the seat metal frameusing an experimental modal analysis as reference. Then, using a pure airborne excitation with the foam cushions alone in the concrete cavity, we have correlated the absorption properties ofthe poroelastic finite element modeling, with all trim layers included. Finally, the fully coupledvibro-acoustic response of the complete seat with structureborne excitation has been computedand correlated with measurements. The trim FEM correlation results are astonishly goodregarding the complexity of the problem and of the interfaces between the various components ofa complete seat up to 600 Hz.