Research on damage response of pre-cracked steel plate under underwater shock wave

The damage response of pre-cracked steel plates is studied experimentally and numerically. Four types of pre-cracked steel plates are subjected to shock wave loading experiments. The damage response of the steel plate includes plastic deformation and structural failure. The underwater shock wave is generated by the underwater shock tube device. Three digital image correlation is used to record the deformation process of steel plates. The plastic deformation stage of steel plate is deduced theoretically by the momentum theorem. The relationship formulas among deformation velocity, shock wave intensity and steel plate thickness are derived. The validity of the formula is verified by the experimental and simulation results. The generation and propagation of new cracks in pre-cracked steel plates are analyzed by numerical simulation method. The section image of the crack is obtained by scanning electron microscopy. The cross-sectional characteristics of the crack show tensile fracture. It is found that the new crack occurs at the stress concentration of the pre-crack tip. The generation and propagation of new cracks are affected by the material properties in different directions. The numerical study shows that the Angle change between the two pre-cracks does not affect the damage morphology. It is found that when the number of pre-cracks increases, the stress concentration at the tip of the outermost pre-crack is the most obvious. Therefore, the first cracking point of the steel plate is the tip of the outermost pre-crack.