Transmission Loss trim FEM simulation of lightweight automotive dashboard insulators with consideration of the instrument panel
Résumé
In previous studies, good correlation results between Transmission Loss measurements and Transmission Loss FEM simulations on dashboard or floor insulators were obtained. Regarding dashboard insulators, those works were done without considering the Instrument Panel. The weight reduction strong trend in vehicles design impacts obviously the noise treatments. In order to ensure an equivalent noise reduction performance, a way to proceed is, for example, to reduce the heavy layer (septum) weight and to compensate the loss of insulation by adding an absorption layer. Without taking into account the absorption and masking effects linked to the presence of the Instrument Panel the overall insulation performances of the front vehicle unit are not properly estimated. In this paper, a numerical study dealing with Transmission Loss simulation of a dashboard insulator with consideration of the Instrument Panel including absorbing felts was carried out in order to predict the insulation performances of a complete front vehicle unit. In this numerical study, weight localization on dashboard insulators was optimized in order to improve noise reduction performances for airborne and structureborne noise excitation in the middle frequency range. Finally a ranking, between all studied solutions, from pure absorbing systems to highly insulating noise treatments is presented.
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