有限元+边界元——修正的模态分解法预报水下旋转薄壳的振动和声辐射

本文提出了一种有限元+边界元——修正的模态分解法用于预报水下结构的振动和声辐射问题.通过引入结构的剩余模态计入被忽略的高阶模态的准静态响应,使模态分解法的收敛性大大改善.文中以轴对称力作用下水下弹性薄球壳振动和声辐射问题为例进行了数值计算,给出了ka=1,2,3和4时球壳表面位移、声压和远场辐射声的计算结果.与原有的方法比较可见,该方法提高了模态分解法的收敛性,特别对远场辐射声指向性尤为明显。

A finite element+boundary element-modified modal decomposition method for vibration and sound radiation from submerged revolutional shells

A Finite Element + Boundary Element-Modified Modal Decomposition method (FBMMD) is presented for predicting the vibration and sound radiation from submerged revolution-al shell. Improvement has been made in FBMD Method to accelerate the convergence by introducing the residual mode which takes into account the quasi-state contribution of all neglected modes. As an example, the vibration and sound radiation of a submerged spherical shell excited by axisymmetric force are studied in case of Ka = l, 2, 3 and 4. From the calculated results we see that the FBMMD method shows a very significant improvement to the accuracy of surface sound pressure, normal displaoement and far-field pattern of sound radiation, especially to the results of far-field pattern.