含裂纹弹性结构对声散射作用研究

ANALYSIS ON ACOUSTICAL SCATTERING BY CRACKED ELASTIC STRUCTURES

研究了含裂纹的弹性结构对声的散射作用 .应用分配形有限元和边界元相结合的方法于含裂纹的结构声相互作用问题 .利用二级分形有限元方法对含裂纹结构进行离散 ,这将使得自由度大为减少 ;使用边界元方法计算外域散射声场 ,这将自动满足无限远辐射边界条件 .数值结果初步表明 :(1)随着裂纹深度的增加 ,结构声耦合系统的共振频率将下降 ;(2 )裂纹附近的声场所受的影响更为明显 .

The acoustical scattering by cracked elastic structures is studied. The mixed method of boundary element and fractal finite elemnt is adopted to solve the cracked structure-acoustic coupling problems. The fractal two-level finite element method is employed to model the cracked structure, which can reduce the (DOFs) greatly, and the boundary element method is used to evaluate the exterior acoustic field which can satisfy automatically Sommerfeld's radiation condition. Numerical examples show that the resonance frequency decreases as the crack depth increases, and the effect on the acoustical field by the crack is particularly pronounced in the vicinity of the crack tip.