中文摘要：

根据薄板结构的形状特点，采用8个节点等参单元离散结构，对其周围的媒质采用20节点三维等参单元离散结构，建立薄板流固耦合系统模型及其声辐射模型．通过理论计算可知：在不同媒质（大气、煤油、水）中，媒质的密度越大，薄板结构的第一阶频率越小；薄板的各阶振型不受媒质密度影响，薄板各阶振型影响其声辐射效率；薄板的频率特性变化，薄板结构的声辐射特性也发生变化；薄板的厚度增加会降低结构振动基频．空气中薄板结构模态测试结果与考虑薄板周围媒质的影响薄板模态计算值一致．

英文摘要：

From the thin plate structure, 8-node iso-parametric element is used to discretize the structure while 20-node iso-parametric element is used to discretize its surrounding media. The fluid-structure coupling system model and sound radiation model were built. The more great the density of the media is, the less the first frequency of the thin plate is. The media density does not affect the thin plate vibration figure of orders. The vibration figure affects the thin plate sound radiation effective. The sound radiation of the thin plate changes with its frequency characteristic changes. The thickness of the thin plate reduces the basic frequency. The tested frequencies agree with the calculating frequencies according with the fluid-structure coupling.