Simulation of Resistant Shock Capability of Missile Launcher Based on DDAM

Abstract

Simulation is the important method for shock-resistant ability design of shipboard equipment. And shipboard equipment shock-resistant ability is the one of important factor of ship life ability. Four- missile launcher resistant shock ability has been evaluated by American navy Dynamic design analysis method (DDAM). The Four- missile launcher has maximal value of displacement at Z direction, and has maximal value of mises stress at X direction because Four- missile launcher has less stiffness at Z direction and has bigger stiffness at X direction. In order to decrease the value of mises stress at X direction, could decrease stiffness of X direction suitably. It is ineluctable to Navy ship suffers attack from torpedo, mine, depth bomb and so on. Sometimes, although ship keeps the airproof capability of hull, but marine equipments installed on deck and hull, lose the function because of strong shock from underwater explosion (UNDEX), so ship lose his battle effectiveness. Dynamic design analysis method (DDAM) is the important one of assessment method for resistant shock ability of marine equipments. This method is based on a great deal of UNDEX experimentation , it's essence is shock response spectrum method. In this paper, the FEM model of Four- missile launcher has been built, and resistant shock ability of Four- missile launcher with this FEM model has been assessed based on DDAM. The simulation results show that the stress intense part locates at the combination within launcher and launcher, launcher and rack and the Four- missile launcher has greater value of displacement at Z direction, and has greater value of mises stress at X direction . The results from this paper has certain value to the design of resistant shock ability for marine equipments. II. SIMULATION A. FEM model The FEM model of launcher and rack has been built with Ansys program. The FEM model has 12346 nodes and 24656 element aggregately. The total mass of rack and launcher is 5366kg. The launcher has been modeled with shell element and the rack has been modeled with beam element. The material of launcher is aluminum alloy with 170Mpa fatigue yield limit, Young's modulus of 70Gpa, Poisson's ratio of 0.33, density of 2600kg/m3,. The rack is beam element, its material is A4 steel with Young's modulus of 200Gpa, Poisson's ratio of 0.3, density of 7800kg/m3, yield strength of 300Mpa. The coupling of rack and launcher, launcher and launcher is MPC(Multi- point constraints) element. The direction of shock is showed by fig.2.