Impact Sensitivity Test and Ignition Response Simulation of HMX/Al/HTPB Cast PBX Tablet by Drop Hammer

In order to study stress state and ignition mechanism of cast octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)/Al/hydroxyl-terminated polybutadiene (HTPB) polymer-bonded explosives (PBX) by drop hammer impact, the impact force test system of the KAST drop hammer apparatus was set up with force sensor and high-speed photography. The impact force load curve of the PBX tablets at different drop heights was obtained. The characteristic drop height value H₅₀ of cast PBX tablets was measured to be 46.5 cm. Combined with the morphology characterization results of HMX/Al/HTPB cast PBX, the temperature rise process was numerically simulated from macroscopic and microscopic scales, and the corresponding ignition characteristics were discussed. The accuracy of the simulation results was ensured according to the impact sensitivity experiment. Based on the thermomechanical coupling algorithm, the impact ignition behaviors of cast PBX tablet were studied from macro scale. The results show that considering the damage and friction effect inside the PBX tablet during the impact process, the critical drop height of the impact ignition response of PBX tablets is determined to be between 46 and 48 cm by the temperature rise ignition curve. The macroscale simulation results are consistent with the impact sensitivity test results. The internal stress and hot spot of HMX/Al/HTPB cast PBX were mainly concentrated at the interface between explosive particles and the binder from the microscope simulation results. The stress and temperature increases between binder and explosive particles were higher than those of other tablet areas. The temperature rise inflection point of impact ignition behavior of HMX/Al/HTPB cast PBX tablets is 617 K.