Multilevel Shell Structure Dynamics Analysis

The mechanical environment of water-exit process of submarine vertical-launched missile is very complex, launching of the water from moving submarine the missile goes through period of in the cylinder,in water and out of water. The force and moment change greatly, and under the possible random factors as currents and waves, the structure of missile takes great trails.In order to avoid the destruction of the structure of missiles in this process, generally adopted to improve the physical structure and reduce the load in engineering. Stability of the multilevel shell and walled shells are studied deeply in this thesis. Based on testing feasibility of the software, the paper has mainly analyzed the problems of multilevel shell's buckling load, mode, the parameters which effect the critical load in buckling of multilevel shell, expected to provides technical reference for improving the physical structure.The paper has first concluded and deduced the equations of shell's buckling load for different structures, then testing feasibility of ABAQUS software to calculate the shell's buckling load. Then the paper has studied stability of multilevel shell structures. After built the models of 2 and 3 level shells, the paper analyzed the buckling of multilevel shell. Under the axial load the buckling load with clamped supported edges is less than with simply supported edges. And compared to the shells with same length and thickness, the buckling load of the multilevel shells is smaller, on the high buckling mode it is obvious.Based on summing up the parameters which may influence the buckling load of the walled shells, the paper has analyzed the effect of shell thickness, grid density, boundary ,size of adapter, tendon size and number to the walled shells.Under the axial and radial load, the paper has analyzed the stability of the multilevel shell and walled shells. The results has shown that they got the similar conclusion. When its radial load is relative small, it could enlarge the axial critical buckling load. When the radial increase to a Critical value which is far less than the radial critical buckling load, the axial critical buckling load fall rapidly.The results of simulation of the multilevel shell and multilevel walled shell can be referenced by the designs of structures and launcher security.