Numerical analysis of damage characteristics of temperature gradient ice layer under underwater explosion load

To explore the ice-breaking effect of underwater explosion in polar low-temperature environments, the LS-DYNA software was used to conduct numerical analysis on the underwater explosion ice-breaking process. Considering the temperature gradient of ice layers in polar low-temperature environments, the dynamic response process and failure mechanism of ice layers during the shock wave stage and bubble pulsation stage were analyzed. The influencing factors of underwater explosion ice-breaking effect and their changes in the failure mode were discussed. The influence laws and reasons of each factor were analyzed from the perspectives of stress wave propagation and energy release. The research results show that under complete typical working conditions, the dynamic response process of ice layers under underwater explosion loads can be roughly divided into five stages: the stress wave action stage, the initial crack initiation stage, the local bending deformation stage, the overall rebound stage, and the jet penetration stage. Increasing the charge mass brings limited improvement to the ice-breaking effect. The blast distance can directly affect the energy transfer efficiency, and there exists an optimal blast distance that makes the fragmentation zone effect the best, while the optimal blast distance for the crack zone is larger. The influence of ice layer thickness is nonlinear. As the thickness increases, the range of the fragmentation zone gradually decreases and tends to be stable, while the range of the crack zone dominated by bubble movement may increase under certain conditions. Through numerical simulation methods, it was found that the failure modes of temperature gradient ice layers and equivalent temperature ice layers are similar, but the fragmentation effects under the same explosion loads are slightly different.