Fracture Mode and Ignition Response of PBX Explosives under Crack Extrusion Loading
Structural weaknesses such as cracks are easy to occur during the service of weapon charge. For the circular crack,the crack extrusion loading experiments of PBX-3 explosives and its simulants were carried out. Through structural design,the macroscopic cracks in a sample would not be destroyed during the disassembly process after the experiment,and the original appearance of the cracks would be preserved for observation and analysis. The whole dynamic process of sample extrusion was recorded by 45-degree mirror reflection imaging and high-speed photography. Euler-Lagrange coupling method was used to simulate the crack extrusion process of explosives. The model parameters were checked with the experimental data under unignited condition,and the ignition condition was recalculated with the checked model. Based on the equivalence of doing work and heating to increase the internal energy,the main ignition mechanism and ignition time were analyzed. The results show that the slip zone and dead zone are formed in the sample under crack extrusion loading,and the interface between the two zones is conical. For φ0.8 mm crack,the ignition can be caused by the extrusion velocity of only 4.2 m/s under strong confining pressure,and the combustion reaction intensity increases with the decrease in crack size.The numerical results of extrusion stress,velocity and fracture mode are in good agreement with the experimental results. The extrusion friction power between the slip zone and the dead zone is as high as thousands of W/cm2,and the ignition time is in the order of 100μs. The important mechanism of ignition is the extrusion friction temperature rise at the interface between the slip zone and the dead zone.
万方数据
维普
