Research on the dynamic response of pressurized cylindrical shell structures subjected to a near-field underwater explosion

Abstract

To study the dynamic response of a pressurized thin-walled circular tube structure subjected to a near-field underwater explosion, deformation and damage tests of a pressurized cylindrical tube shell with different internal pressures and wall thicknesses with the effects of an underwater explosion from 2 g of explosives at different stand-off distances were carried out in a water tank. LS-DYNA finite element software was used to carry out relevant numerical simulations to explore the anti-explosion mechanism of a pressurized cylindrical shell structure affected by factors including the initial internal pressure, the thickness of the cylindrical shell, and the stand-off distance. The simulation inputs are high-speed photography images and the damage results of the cylindrical shell. The simulation results highlight the bubble pulsation, action process deformation, and energy change of the cylindrical shell. The results indicate that an increase in the initial pressure of the cylindrical shell can effectively improve its anti-explosion ability, while the different stand-off distances of r = 12 cm and r = 9 cm correspond to the same initial internal pressure. Increasing the initial internal pressure also causes the deflection difference of the cylindrical shell to decrease. The modeling results also indicate that an increase in the wall thickness may weaken the anti-explosion ability of the cylindrical shell, which has an initial internal pressure of Pr = 0.7 MPa. After an underwater explosion, the maximum displacement difference of a cylindrical shell with thicknesses of h = 1 mm and h = 1.5 mm is less than the maximum rebound distance difference. With this decrease in the distance, the proportion of the high-pressure cylindrical shell subjected to a shock wave increases while the proportion of bubble pulsation decreases. Specifically, the maximum proportions of bubble pulsation are 30% and 92% at the stand-off distances of 3 and 12 cm, respectively.