Marine vehicles in their operation as military vehicle are susceptible for underwater explosion from mines, torpedo etc. The damage inflicted on such structures made of ductile materials can be large deformation, tearing, rupture etc. It is imperative to design such structures for withstanding explosive loads. The damages inflicted will be mostly localized between the frames and stiffener, which can be considered as plate clamped at the edges. Hence, an attempt has been made in this paper to study the localized deformation of thin mild steel plates subjected to underwater explosion through limited explosion bulge test using small explosives. The experiments exhibited Mode I: large deformation, Mode IIa: Partial tensile tearing, Mode IIc: central rupture and Counter Intuitive Behaviour (CIB). The problem is simulated numerically using LS DYNA nonlinear finite element code considering fluid – structure interaction and the results compared with experiments. Based on the confidence gained for the air backed conditions, the analysis is extended to water backed (fully filled, 75% filled, 50 % filled) conditions and results obtained for the large deformation behaviour for various conditions are presented. The results indicate that the large deformation behaviour considerably reduces the central permanent deformation under water backed conditions compared to air backed conditions due to the fact that part of shock wave gets transmitted to the water medium behind the plate in water backed conditions.

作为军用车辆运行的海洋车辆容易受到水雷、鱼雷等水下爆炸的影响。这种由延性材料制成的结构造成的损坏可能是大变形、撕裂、破裂等。设计此类结构以承受爆炸载荷势在必行. 造成的损坏主要集中在框架和加强筋之间，可以认为是在边缘处夹板。因此，本文试图通过使用小型炸药的有限爆炸膨胀试验来研究薄钢板在水下爆炸时的局部变形。实验展示了模式 I：大变形，模式 IIa：部分拉伸撕裂，模式 IIc：中心破裂和反直觉行为 (CIB)。该问题使用 LS DYNA 非线性有限元代码进行数值模拟，考虑了流体 - 结构相互作用，并将结果与​​实验进行了比较。基于对空气背衬条件获得的置信度，分析扩展到水背衬（完全填充、75% 填充、50% 填充）条件，并提供了各种条件下大变形行为的结果。结果表明，与气背条件相比，水背条件下的大变形行为大大降低了水背条件下的中心永久变形，因为部分冲击波在水背条件下被传递到板后面的水介质中。基于对空气背衬条件获得的置信度，分析扩展到水背衬（完全填充、75% 填充、50% 填充）条件，并提供了各种条件下大变形行为的结果。结果表明，与气背条件相比，水背条件下的大变形行为大大降低了水背条件下的中心永久变形，因为部分冲击波在水背条件下被传递到板后面的水介质中。基于对空气背衬条件获得的置信度，分析扩展到水背衬（完全填充、75% 填充、50% 填充）条件，并提供了各种条件下大变形行为的结果。结果表明，与气背条件相比，水背条件下的大变形行为大大降低了水背条件下的中心永久变形，因为在水背条件下，部分冲击波会传递到板后面的水介质中。