Effectiveness of Updated Vibro-Acoustic Models for Analysis of Interior Noise in Cavities

In the process of NVH design of cavities, accurate vibro-acoustic models are required. Such models at first can be used to obtain an accurate prediction of the sound pressure response due to the structural excitations. Such predictions enable to establish whether the noise levels are within the acceptable limits or not. They can also be used to identify the acoustic and the structural modes and the boundary panels that contribute to the interior noise. These contributions can be quantified effectively via acoustic, structural and boundary panel participation factors (AMPF, SMPF and BPPF). These tools are very important for a quick identification of the trouble spots and for making decisions for modifying the design of a cavity. The structural dynamic modeling errors, which at times are difficult to eliminate in a structural FE model, can affect the accuracy of the vibro-acoustic FE models in analyzing these contributions and arriving at correct design decisions. FE model updating of the vibro-acoustic FE models can be a potential strategy for improving their accuracy and reliability. This aspect however has not been addressed in the literature. In view of this, the objective of this paper is to analyze the influence of structural dynamic modeling errors on the accuracy of participation factors to identify the noise sources and to see how updated models can be used to obtain accurate prediction of these factors and thereby an accurate picture of noise sources in the cavity. It is found that the updated vibro-acoustic models based on both the direct and the iterative method can be used effectively in obtaining an accurate ranking of the contributing sources to the interior noise.