封闭弹性长方体与柱状体连接结构的辐射声场分析

建立了以机械方式连接的封闭弹性长方体与弹性圆柱体的外辐射声场模型。通过在弹性板和壳的四周以及两弹性结构连接点之间施加假想的弹簧系统模拟不同的边界条件和连接条件,利用汉密尔顿函数和瑞利-李兹方法,推导出了腔体外辐射声场的解析解。该模型充分考虑了弹性结构之间的振动耦合以及弹性结构与腔体内声场之间的耦合。通过算例表明,弹性结构的辐射声场主要由其中的直接受力件的辐射声场所决定;弹性结构连接点处线弹簧的刚度变化对辐射声场的影响较旋转弹簧大。同时,运用有限元法计算两个腔体内的声模态和弹性结构的振动模态,及其耦合系数,结合边界元法计算出腔体外的声压响应,并将此数值仿真结果与前面导出的解析结果进行比较,验证理论推导的正确性。

Analysis of Sound Radiation from Elastic Rectangular Enclosure and Cylindrical Enclosure Connected by Mechanical Joints

The model of sound radiation from elastic rectangular enclosure and cylindrical enclosure connected by mechanical joints is constructed. A general formulation considering the full coupling between the subsystems(plates, shell and cavities) is developed. In the model, virtual springs are installed along the boundaries and at the connected points of flexible structures to simulate variety of boundary conditions and joint conditions. The sound radiation of the whole enclosure structure is deduced by using Hamiltonian function and Rayleigh-Ritz method. Two main issues are reached. One is that the sound radiation of the enclosure structure is governed by the part excited directly, the other is that the translational stiffness at connected points is of more influence on the sound radiation than the rotational stiffness. Then, modes of sound pressure and flexible structures are obtained by FEM. Modal coupling coefficients are synthesized. Finally, the responses of sound pressure are worked out by BEM. The simulation results are satisfactory, coinciding well with the analytical ones.