Analyzing Structure Borne Sound Transmission in Car Body Using Combined FE/SEA Techniques

Statistical Energy Analysis (SEA) method is mainly used in automotive industry to build-up comprehensive models of the vibratory energy transmission throughout the body-in-white and to perform estimates of the acoustic performance on the full-trimmed vehicle. If the latter use is given rather satisfactory predictive results, the former is requiring more expertise and backward experience from testing. The main cause of dispersion is due to the use of simple analytical formulae to describe complex structural behavior in current SEA software and to the choice of a SEA portioning into subsystems that makes the model accuracy dependant on the user's choice.

Nevertheless, SEA models are very attractive as they are small, easy to optimize and include the main dynamics features. A technique for improving accuracy of SEA models, especially for structure-borne-sound by interfacing them with Finite Element (FE) modeling is presented. A main interesting feature of this technology is to derive an auto-portioning of the system into subsystems. The SEA model is de facto becoming independent of the user. Robustness is also improved. Comparison between tests and predictions are shown on industrial cases.