Failure mechanisms of titanium alloy cylindrical pressure hulls under combined hydrodynamic pressure fields and implosion shock loading

Pressure hulls in deep-sea environments are exposed to extreme hydrostatic pressure and implosion shocks caused by the failure of brittle structures, which may result in catastrophic failure and the underwater implosion of adjacent pressure hulls. It is, thus, essential to investigate the destructive effects of implosion shocks induced by the localized rupture of brittle structures on adjacent pressure hulls under deep-sea conditions. First, a triggered implosion and shock experiment is conducted to examine the dynamic response characteristics of titanium alloy cylindrical pressure hulls under the combined effects of the deep-sea environment and implosion shocks. Then, a high-accuracy numerical method for fluid–structure interactions based on the arbitrary Lagrangian–Eulerian method is developed to analyze the failure mechanisms of such hulls under implosion shocks at varying standoff distances. The results indicate that the plastic deformation induced by implosion shocks is the predominant factor contributing to the failure of cylindrical pressure hulls when the standoff distance is less than 0.33r0. As the standoff distance increases, the influence of the shock wave decreases, resulting in the predominant factor shifting toward an overall instability caused by the hydrodynamic pressure field.