Sound-Insulation Layers Low-Frequency Modeling, Using the Fuzzy Structure Theory 2009-01-2221
Over the past few years, car manufacturers have improved their numerical models for the prediction of the trimmed body vibroacoustic response. In the low-frequency band [20, 200] Hz, sound-insulation layer modeling remains a critical topic. Recent work allows the connection of the structure and cavity through a transfer matrix computed from a FE model of the sound-insulation layer. Nevertheless, such an approach requires a FE model of sound-insulation layer, which may not be available in early design stages. Moreover, considering the uncertainty of the design itself, in addition to material uncertainty, a deterministic model may not be appropriate. In this paper, a simplified model of sound-insulation layers based on the fuzzy structure theory is proposed. The simplified model is obtained by performing a statistical averaging of the internal dynamical degrees of freedom of the sound-insulation layer and is governed by three parameters: the modal density, the coefficient of participating mass and the damping rate of the sound-insulation layer. In order to improve the prediction, the model errors introduced by the simplifications as well as material properties uncertainty are modeled using a nonparametric probabilistic approach. After the fuzzy model is set up theoretically, it is applied to a simplified case. The way how the fuzzy model's parameters are related to design parameters will then be discussed. Finally, the application to a full trimmed body is presented.