Numerical Simulation and Test of Wet Modal for Shell Structure in Shallow Water

The modal characteristics of the vehicles’ structure in shallow water directly affect the dynamic response of it in water-exit. A wet modal simulation model of shell structure of undersea vehicle in shallow water is established based on the acoustic-solid coupling method, and the influence of the change of immersion depth on the wet modal characteristics of the structure is analyzed by using the zero-sound pressure free surface simulation method. The wet modal test system of this shell is designed and built, and the wet modal feature information of this model is obtained by using PolyMax method. Comparison between simulation and test results shows that the simulation results are in good agreement with the test data, which verifies the validity of the wet modal simulation model and suggests its applicability to the wet modal analysis of structure in shallow water. In the condition of shallow water, the wet modal frequency of this shell decreases gradually with the increase of the immersion depth, and then tends to a stable value. The damping ratio of wet modal is 2 to 8 times that of the dry modal, and there is no obvious dependence on the immersion depth