Muffler Transmission Loss Based On The Boundary Element And Finite Element Coupling Model Prediction

BEM, an efficient numerical method to solve wave equation, is widely used for predicting acoustics performance of a building pipe silencer system. However in many researches about it, when a muffler is modeled by the BEM, the walls of the muffler have been assumed rigid and the effects of the end plate have been ignored. In order to analyze the effects of the muffler's structural flexibility, a BEM code consisting of three-node triangular continuous elements is used to discretize the acoustic cavity system, and a FEM code used for the structure analysis is obtained by combining the plate bending element and the plane stress element in this paper. According to the compatibility and equilibrium for the common boundary conditions, these BEM and FEM models are coupled. The predicted TL results by the BEM-FEM coupled model demonstrate its efficiency and precision. And they also show that there have some dip-peaks in the TL curve around resonant frequencies of the end plate. In this paper, an improved method is introduced to derive the four-pole parameters for use in the BEM. The major advantage of the improved method is that it provides a faster method for computing the TL when the four-pole parameters are involved in the computing.