Numerical Simulation Of Response Of Shell Structures To Underwater Shock

In this paper, responses of several shell structures, which was subjected to an underwater explosion shock wave, were simulated, using ANSYS/LS-DYNA. The research objects were submarine and general cylindrical shells with stiffening ribs.Firstly, the propagation of underwater explosion pressure was analyzed, and the dynamic effect on a cylindrical shell was simulated. During the study, simulation of far-field explosion using ANSYS/LS-DYNA needs a huge number of water elements, and the pressure of shock wave was excessive reduced.Secondly, in order to reinforce the shell, and improve shock resistance of the shell, several methods was tried, such as changing the geometry parameters of stiffening ribs, increasing thickness of the cylindrical shell, and so on. These methods were compared, and the results show that, by reducing distances between reinforcement ribs, or increasing shell thickness on the basis of reinforced cylindrical shell, the impact resistance ability of shells were effectively improved. At the same time, changing the bar sizes also can achieve better impact resistance ability of cylindrical shells.Then finite element models of double-shell structure and single-shell with surrounding water were respectively built, and the response of two shells under the effect of underwater explosion shock was simulated. Results were collected for comparison to find the effect of the outer shell and the fluid between two shells on the propagation of shock wave and the response of inner shell. The results show that the effect is very small.Finally, a finite element model of submarine was established, based on the geometry parameters of a real submarine. Numerical simulation of the response of the submarine subjected to an underwater explosion shock was carried out. Responses of the shell under different conditions were analyzed, such as stress and strain responses, velocity and acceleration response and the energy absorption of internal structure and external shell. Stress distribution, on the blast surface, along the length direction of the submarine, was summarized. Then the responses under different conditions were compared. Unfavorable factors for the impact resistance of this shell structure were pointed out, and advices were given for improvements. The results of this paper can provide a reference for improving the anti-impact ability of submarines when an underwater explosion occurs.