Transmission Loss Prediction through a Curved Structure-Cavity System with Attached Sound Packages by means of a Hybrid Patch Transfer-Green Functions Approach

This paper assesses and discusses the modeling of the transmission loss (TL) of curved single and double walls with attached sound absorbing materials (light foam and spring-mass treatments). The TL of the studied systems is predicted by an approximate approach that employs a Patch Transfer functions (PTF) technique to couple the standard finite element (FEM) schemes of the curved panel and its cavity with an analytical model of the noise control treatments. To compute the PTF relations, the structure and the cavity are described by FEM while the effect of the unwrapped sound package is provided by a Green functions methodology based on the fast Transfer Matrix Method. The results are systemically compared with a classical coupled Finite Element/Boundary element method (FEM/BEM) wherein the curved structure and its cavity are modeled by FEM while the radiation from the transmission hole and the blocked pressure on the excitation side are modeled using the BEM. The effect of the radius of curvature on the accuracy of the hybrid Patch Transfer-Green Functions method is assessed. Finally, the proposed method allows for a considerable simplification and a fast comparison of the performance of various acoustic treatments within the same structure and cavity.