A SMOOTHED FINITE ELEMENT-PERFECTLY MATCHED LAYER METHOD FOR TWO-DIMENSIONAL STEADY-STATE RADIATION ACOUSTIC FIELD PROBLEMS

Aiming at the problem of low accuracy of finite element method (FEM) for exterior acoustics analysis, the smoothed finite element method- perfectly matched layer (SFEM-PML) method is proposed for the analysis of two-dimensional steady-state acoustic radiation problem. In SFEM-PML, the computational region, truncated by perfectly matched layer(PML), is discreted into four-node isoparametric elements. The mapping relation between the PML's parameter coordinates and Cartesian coordinates is implemented by using the exponential absorbing function. In order to recast the domain integrals involving shape function gradients to the boundary integrals involving only shape functions，the radiant acoustic stiffness matrix is calculated by using the smoothed acoustic pressure gradient matrix. Numerical example of a two-dimensional radiation field of acoustic cavity of automobile is presented，which shows that SFEM-PML achieves better absorbing effect in PML, and higher accuracy in the computational region as compared with FEM-PML. Hence the SFEM-PML can be well applied in solving two dimensional acoustic radiation problems, and has a wide application foreground.