A Method for Vibro-Acoustic FE Model Updating of Cavities Using Frequency Response

Interior noise due to structure-borne sources has always been a cause of concern in the cavities encountered in aerospace, automotive and other applications. In the design of such cavities, the coupled vibro-acoustic model is the key to evaluate its structural and acoustic design. It can also be used as a diagnostic tool to identify the potential noise sources and to assess the effectiveness of the proposed design modifications. However effectiveness of this model greatly depends on the accuracy of predictions made by these models. It is however seen that often there are inaccuracies in the modeling of structural and acoustic domain of a cavity. Methods to deal with structural and acoustic modeling inaccuracies have been developed in the past through FE model updating for uncoupled FE model, while the same have not been addressed in the context of a coupled vibro-acoustic FE model. This issue forms the topic of this paper. This paper proposes a method for updating vibro-acoustic FE model using frequency response function with the aim of identifying the material property of flexible surface of cavity. The updating problem is formed as constrained optimization. The method requires measured vibro-acoustic frequency responses of the system. Updating parameters related to the material property and the stiffness of joint between the plate and rectangular cavity are used. The effectiveness of the proposed method is validated through numerical studies on a 3D rectangular box cavity. The robustness of the method under presence of noise is also investigated. The proposed method is found to work satisfactorily to correctly estimate the updating parameters and yield an updated model that correlates well with the measured frequency response.