水下发射航行体在出水过程中，随着沾湿表面积减少，航行体与周围流体相互作用而产生时变流固耦合效应，并引起结构动力学特性的变化。同时，考虑到航行体通常采用舱段式结构，各舱段在连接处存在非线性接触问题，对结构动力学特性也存在实质性影响。在考虑上述因素影响的情况下，将航行体简化为Timoshenko梁模型并利用有限元方法对结构动特性和动响应进行计算分析，得到了出水过程时变流固耦合效应及连接刚度非线性对航行体结构固有频率及动力响应的影响规律，在此基础上进一步分析了连接结构、载荷及出水速度的变化对结构动响应特性的影响。

While underwater launched vehicle crossing water free surface, time-varying Fluid Structure Interaction effect is formed due to the interaction between the vehicle and surrounding water and the decrease of wet surface. As a result, the variety of structure dynamic property occurs. Moreover, Compartment structure is widely adopted in underwater lunched vehicle. The joint part between two compartments causes nonlinear contact problem, which effects structure dynamic property. Considering the above factors, the vehicle is simplified into a Timoshenko beam, and mode analysis and transient analysis are conducted. The different effect regularity of the time-varying Fluid Structure Interaction and the nonlinear stiffness at the joint part on the structure natural frequency and dynamic response has been obtained. Besides, the effect of joint structure, external load and water exit velocity on structure dynamic response is analyzed.