Simulation Analysis of Critical Loads of Cylindrical Pressure Hulls With Initial Defects

Pressure hull is an important part of underwater unmanned vehicle, which is the main provider of buoyancy force and withstands immense seawater pressure. Initial geometric defects will lead to the reduction of the ultimate strength of the structure, and the first-order mode is often used as the initial geometric defects in finite element analysis to study the ultimate strength of the structure. In this paper, based on ABAQUS finite element simulation software, an internal corrugated pressure hull model is established, and first, linear eigenvalue buckling analysis is performed on the internal corrugated pressure hull to obtain the first 30 order linear buckling modes of the pressure hull. Then, each order of buckling modes and the superposition of multi-order modes are respectively taken as the initial defects, and the nonlinear buckling analysis of the inner corrugated pressure hull is performed to obtain the critical buckling load. The results show that: for single-mode defects, the most unfavorable geometric defects are generally low-order modes. When considering the defects of the superposition of multi-order modes, with the increase of combined orders, the critical buckling load shows a decreasing tendency, and the decreasing amplitude changes from large to small and then large again. When the combination of orders from 1-8 to 1-24, the critical buckling load shows a slowly decreasing tendency, that the variation is within 3.28%.