| High explosives in the devices may ignite, burn, explode and even detonate, when subjected to unexpected stimulation such as drop, hit and cook off in the process of production, assemblage, transportation, storage and usage. It bring huge threaten for explosive safety. Now the main problems in high explosive safety is poor understanding of the mechanism and process, and faultiness of simulation method of non-shock initiation in the condition of accidents. So the analysis of the respondent, mechanism and development of high explosive in the condition of non-shock initiation, and the development of numerical simulation method is important for evaluation of the safety of high explosives and devices. In this thesis, the research is done in mechanism and simulation technique of friction and shear ignition of high explosives. Also, the numerical simulation of thermal explosion problem is studied and an open void method of slide line based on Lagrangian unstructed arbitrary N-polygon grids is developed.Based on previous friction ignition model of high explosives, friction ignition model of high explosives with multi-media in system is developed which can explain that the binder makes explosives insensitive to friction and time duration of friction effects friction ignition time by numerical simulation. The friction sensitivity test of four insensitive single compound explosives is simulated. The order of friction ignition time of theses four fit the test, which show wide applicability of the friction ignition model. The effect of thermal reaction rate on ignition is observed by calculation. In different friction condition, the order of the friction sensitivity of high explosives may be changed.A composite explosive friction ignition model is developed. Based on the component of different explosives, the calculation algorithm of physical parameters is set up for two kinds of composite explosives which one is with one and another is with more kinds of single compound explosives. The friction sensitivity test of several composite explosives is simulated, and the order of ignition time is agreement with the result of experiments. The constrained friction test with low pressure with long pulse duration and friction sensitivity test of explosive tablet is simulated, the ignition time of high explosives is agreement with the result of test.Shear ignition model of high explosives is developed. An elasto-plastic constitutive model with damage is used for high explosives. The shear plastic work is transformed into heat. Arrhenius and two terms reaction rate by Lee-Tarver is used to describe the reaction of high explosive under shear strain. The shear ignition test is numerical simulated. The simulation is agreement with the result of test qualitatively, which prove the rationality of method.The numerical simulation of one dimension thermal explosion problem is done for ODTX. The melt of high explosives is considered during thermal explosion, and Arrhenius reaction rate,3-step reaction model and Prout-Tompkins reaction model is used in numerical simulation. The result of 3-step reaction model and Prout-Tompkins model is agreement with experiment data better, and as the boundary temperature is higher than melt point of explosive, the explosive will melt, and ignition time fit experiment data better in the low temperature zone.An open void method of slide line is developed based on unstructed arbitrary N-polygon grids. The method of distinguishing open or closed void state of point and grid and calculation method of velocity of point on slide line is given with open or closed grid. Many conditions of different kinds of grids, different velocity and multi-medium are simulated in the test of a metal flyer impact another flyer and then separate. Detonation driving metal flyer are also simulated, which prove the rationality and adaptability of method. |
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