Collapse behavior of corrugated stiffened pressure shells under external hydrostatic pressure considering actual fabrication imperfections: A reverse modeling technique

The pressure shell is the most critical load-bearing component in submersible vehicles. It is mainly used to withstand the enormous seawater pressure. In this study, a corrugated stiffened pressure shell was proposed to address the problem of low compression performance of the traditional cylindrical pressure shell. Nine corrugated shells made of aluminum alloy with varying corrugation parameters were created using CNC machining. After welding and sealing treatment, hydrostatic pressure tests were conducted on the shells to investigate the impact of parameters such as wall thickness, number of corrugations, and corrugation height on their compression performance. The shells were measured using a 3D scanner, and the resulting data was used for reverse modeling. The analysis focused on the failure behavior of corrugated shells with geometric imperfections under uniform external pressure using nonlinear finite element analysis. The results indicate that increasing the wall thickness or corrugation height can significantly improve the compression performance of the shells. The position of collapse remains consistent with the location of the maximum Mises stress. Furthermore, it was discovered that the corrugated structure also has an additional advantage in retarding the generation and expansion of diamond-shaped defects on the shell surface. The equilibrium paths of all corrugated shells maintained a smooth and continuous state, demonstrating stable buckling behavior. The numerical calculations were in excellent agreement with the experimental results, highlighting the advantages of the reverse modeling technique. This study provides new insights for the structural design of submarine pressure shells and explores more reasonable and feasible stiffening methods.