Experimental And Theoretical Study Of The Main Explosive Particle Size And Particle Size Gradation And Explosives Shock Sensitivity And Energy Output

The relationship between the shock sensitivity and energy output of explosives with particle size and gradation is systematically studied in theory and experiments. The visco-plastic void collapse mechanism and model are used to analyse the major influencing factors and critical conditions of hot spot ignition in the detonation initiation of heterogeneous explosives and typical calculations are conducted. The influencing factors on the detonation builduop reaction rate are discussed on the basis of grain surface burning mechanism and model.Based on the theoretical analysis and existed experimental results,shock sensitivity is not a nature characteristic of an explosive,but related to especial testing methods,testing conditions and judging criterion.The dependence of buildup process on the particle size of explosives is exactly the opposite of the dependence of buildup process on the particle size .The relationship between the shock sensibivity and particle size depends on whether ignition or detonation buildup is domiant process in given detonation initiation proceses. The influence of particle size of HNS and gradation of HMX on the shock sensitivities of their typical composite formulations is experimentally investigated by small scale gap test.The relationshiop between shock sensitivity and particle gradation is systematically studied within a larger particle gradation range for the first time.Furthermore,the effect of particle gradation of the explosives on energy output is studied by both steel dent and detonation velocity testing method for the first time. Main conclusions could be reached by theoretical analyses and experiments as follows: (1)Shock sensitivity decreases with the reduction of particle size of explosives when ignition is dominant process in the detonation initiation.But the situation is the opposite when detonation buildup is dominant process. (2)The effect of patrticle size on ignition and buildup to detonation is adverse.The reduction of particle size of explosives is in favor of buildup but in unfavorable of ignitin. (3)The effect of particle size on energy output is main due to the change of the specific surface area, the specific surface area is decreased, ,the reaction rate of detonation is increased,the energy of chemical reaction is decreased too with decreasing particle size of explosives,so energy output is increased. (4)In the present testing conditions,shock sensitivity increases with increasing content of coarser grains for multimodal distribution explosives. (5)Inthe present testing conditions,detonation pressure and detonation velocity increase with incresaing content of finer grains for multimodal distribution explosives. The result of this dissertation lay the foundation for the design of explosives,other pyrotechnic compositions and detonation initiation and propagation structures,in addition ,are helpful in the further research on detonation initiation mechanisms.