Study On Thermal Vulnerability Factors Of Warheads

This thesis aimed at studying the factors which have an influence on the thermal vulnerability of warheads. The research results could be regard as an support tool to lower the thermal vulnerability of munitions and keep the munitions safe.According to the theory of thermal explosion, the numerical solution of critical temperature of the thermal explosion was established, which is the way of the RDX-based explosives in different aspect ratio. Two kinds of samples whose diameters were φ19and φ30and whose aspect ratios differ too were used in the test. Theirs critical temperature was figured out by the algorithm mentioned above. The results show that when the value of aspect ratio is higher than5, the critical temperature comes to a certain value. When the aspect ratios are the same, the larger the diameter of sample is,the lower the critical temperature is. So it can come to an conclusion that increasing the diameter enhance the possibility of warhead’s thermal vulnerability.Research also studied the relationship between the thermal decomposition rate of explosives and the environmental temperature, especially the relationship between the thermal response characteristics and the free spaces. The experiment results indicate that the environmental temperature and the time of keeping constant temperature are the two critical factors which have an influence on RDX-based explosives’detonation that transition from decomposition. Besides, when the environmental temperature is higher than175℃, the decomposition rate increase sharply. In addition, the free space plays an important role in the thermal response characteristics of samples, when enlarge the free space of samples, the level of thermal response improves obviously.Apart from the theoretical calculations and the experimental study, FLUENT software was applied to simulate the process that the free space affects the thermal response characteristics. Results of the simulation show that ignition place and ignition quantity change with the free space increasing. This simulation result again theoretically explains the effect free space has effect on cook-off test. A lot of factors(aspect ratio, external constraint strength, heating rate, quantity of explosive charge) which have an influence on thermal response characteristics were simulated. A series of measures were got from the simulation, which can lower the thermal vulnerability of samples.The safely use of warheads in practical work and the design of lower vulnerability warheads can benefit a lot from these results, which can be seen as an support tool.