Experimental and numerical study on safety of shelled high explosives during drop

In this study, the safety of shelled high explosives during drop was investigated based on experiments and simulations. First, split Hopkinson pressure bar and L-Spigot drop tests of RU-2D explosives were carried out, the parameters of the constitutive model were obtained by combining the optimization algorithm and genetic algorithm, and the stress-strain data obtained from the simulations agreed with the experimental results. Then, we combined the finite element method with the viscoelastic-viscoplastic-damage constitutive model and the hot spot model based on microcrack friction to investigate the damage evolution and non-shock ignition mechanism of shelled high explosives and analyzed the effects of shell thickness and material. The development of the shear region within high explosives was divided into two stages. The early shear region was formed above the contact region between the plug edge and high explosives and then extended upward along 45°. After the shell started to fracture, the original shear region was significantly strengthened. The formation and evolution of the damage and temperature rise were closely related to the shear region, and the simulation result of the threshold height for ignition was consistent with the L-Spigot test results. With the increase in shell thickness, the initial damage and temperature rise region gradually moved away from the contact region along the shear region, the damage region gradually increased, and the time of non-shock ignition gradually increased. When the fiber-reinforced polymer material was used, the region of non-shock ignition moved away from the contact region, and the time of non-shock ignition gradually increased.