Experimental studies in finite element model updating of vibro-acoustic cavities using coupled modal data and FRFs

The NVH design of cavities in aircraft, cars and other transportation equipment are mainly based on use of vibro-acoustic FE models to analyze low frequency structural vibration and interior noise. In order to improve the accuracy and reliability of these vibro-acoustic models, uncertainties associated with modeling of boundary conditions, joints, damping and acoustic absorption properties of cavity surfaces in acoustic domain, must be taken into account. Finite element (FE) model updating is now recognized as an effective approach to reduce modeling inaccuracies present in an FE model. This paper presents experimental studies in updating of FE model of vibro-acoustic cavity. Two experimental studies are presented. The first experimental study is about updating of structural FE model of the cavity incorporating acoustic loading using modal data based on an inverse eigen-sensitivity approach. The second study involves updating of structural and acoustic parameters of the vibro-acoustic model using frequency response functions based on a constrained optimization based approach. Thus, FE model and experimental coupled modal data and FRF data are integrated to obtain a more accurate vibro-acoustic model. Experimental example of a 3D rectangular-box cavity with a flexible plate is presented. The studies demonstrate that the improvement of the vibro-acoustic FE models through FE model updating can be an effective approach to obtain more accurate vibro-acoustic predictions.