Objective s This study aims to investigate the effects of different types of initial geometric imperfections on the structural response of a ring-stiffened cylindrical shell subjected to underwater explosion loads.
Method A typical titanium alloy ring-stiffened cylindrical shell is selected. A baseline underwater explosion response is first established using an acoustic-structure coupling approach. Based on linear buckling mode analysis, local and global instability modes are extracted to characterize initial imperfections in the shell plating and initial out-of-roundness of the stiffeners, respectively. Numerical simulations are conducted to evaluate their influence.
Results Under identical impact conditions, the maximum plastic strain increases linearly as the shell plating imperfection amplitude increases from 0.2 to 1.0 times the shell thickness. In contrast, when the stiffener out-of-roundness exceeds 0.6% of the cylindrical shell radius, the maximum plastic strain increases abruptly and exceeds the material reference fracture strain, indicating a high risk of structural failure.
Conclusion The initial out-of-roundness of stiffeners exhibits significantly greater sensitivity than shell plating imperfections. The critical threshold lies between 0.006R and 0.007R under the given conditions.
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