浅水域结构流固耦合振动的固有频率计算

摘要

本文首先建立了浅水域声学边界元方程和相应的FEM/BEM耦合振动方程,探讨了水深对结构振动固有频率和振型的影响,流体可压缩性对结构振动固有频率的影响.研究结果表明:水深变化对结构固有频率有影响,随着水深减小,结构固有频率降低,特别是当水深与结构浸深接近时,水深变化对固有频率影响极大,且振型顺序也可能发生变化;而流体的可压缩性对于浅水域结构固有频率影响不大.%The BEM equation for acoustic analysis in shallow water and the corresponding coupled FEM/BEM vibration equation are established,and then the impacts of water depth and the fluid compressibility on the natural frequencies and mode shapes for underwater structures are discussed.The results show that water depth has an influence on the natural frequencies of structures in the way that natural frequencies decrease as the water depth decreases. It is also noted that the natural frequencies of structures change a lot and even the sequence of mode shapes changes if the water depth is very close to the draft of the structure. Besides,the authors find that fluid compressibility has little impact on the natural frequencies of structures in shallow water.