Experimental analysis on dynamic response of pre-cracked aluminum plate subjected to underwater explosion shock loadings

As the main defense component of the ship against the attack of external damage sources, the liquid cabin will inevitably suffer some damage like holes or cracks in the battle because of the explosion fragments or the penetration of high-speed projectiles. The research on the rest capacity and dynamic response of the cabin with different damage cracks due to the underwater explosions is of great significance to the improvement of the protection design of cabin structures and the development of the fluid-solid coupling theory. For the sake of simplicity, an aluminum thin-walled plate with central prefabricated crack was adopted to solve the problem on coupling loads induced by underwater explosion, and an underwater shock wave tube was used to substitute an underwater explosion load to generate the shock loading on thin-walled aluminum plate. The shock wave pressures in the underwater explosion tube and the dynamic deformation responses of aluminum thin-walled plates with central prefabricated crack were recorded by three pressure sensors and two high-speed cameras, respectively. By analyzing experimental results, the history characteristics of the dynamic increase of plastic bulge height and the crack propagation of the aluminum plates were obtained. The results show that the time of the crack growth and the bulge increasing are not synchronized in the dynamic response of thin-walled plate; in addition, the effects of the crack shape and size on the bulge and the crack growth in dynamic response of target plate can be attributed to the trade-off between the energy leakage and the bending stiffness of the target plate. Finally, according to the velocity and acceleration on the target and based on a plastic-rigid material model, we obtain that the target bending angle sine is linear with the radial distance, and the conclusion was well validated by experimental target bending angle data.