Dynamic analysis of underwater launched vehicle during water exit considering contact nonlinearity

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, accompanying with the decrease of wet surface. As a result, a variety of structure dynamic behaviors occur. Moreover, compartment structure is widely adopted in underwater launched vehicle and the joint part between two compartments causes nonlinear contact problem, which effects structural dynamic property. Considering the above factors, the vehicle was simplified into a Timoshenko beam, and the modal analysis and transient analysis were carried out. The specific effects of the time-varying fluid-structure-interaction and the nonlinear stiffness at the joint part on the structural natural frequencies and dynamic responses were discussed. Besides, the effects of the joint construction, external load and water exit velocity on structure dynamic responses were analyzed.