Investigation On Safety Rules And Energy Output Of Composite Charge

In this dissertation, the charge structure of explosive was investigated by numerical simulation, experimental investigation and theoretical analysis. The effects of composite charge structure on safety and energy output of explosive were discussed and the optimized structure was obtained. As we know, through the reasonable charge structure design, the main charge of warhead which contains both the insensitive explosive and high energy explosive has good safety performance and high energy output.The effects on shockwave sensitivity, bullet impact sensitivity and thermal stability of the charge of the composite explosives was studied by the gap test, bullet impact test and cook-off test. The results of gap tests for different charge structures of the explosive showed that the gap thickness of composite explosive is between that of high energy and insensitive explosive. The charge size of the insensitive explosive greatly influences the shockwave sensitivity of the over-all structure. The dependence of the shockwave sensitivity on the height ratio shows first order exponential decay. FEM software has been used to simulate the gap tests of composite charge explosives, the results are identical with the data obtained from the experiments. The simulations of gap test using aluminum, plexiglass, steel and JB-9014explosive as the gap material were conducted. It is found that aluminum has the similar decay effect on shockwave as plexiglass. Due to the quick decay of the shockwave in the steel, the thickness is small while the value in the JB-9014as inert material is consistent with the value in the active material. The details of bullet impact tests for composite charge structure were obtained by using the simulation method. The response law between the charge structures and bullet impact sensitivity were investigated by analyzing the dimensional effect. The insensitive explosive was applied as the external surface of the composite charge explosive and the high energy explosive as internal surface. It is showed that the shooting sensitivity of the composite explosive is lower than single high energy explosive and the length-diameter ratio of the high energy grain has great influence on the safety of explosives which has a size threshold value. Cook-off experiments show that the heating rate and charge structure have great effect on the ignition time and position for composite charge explosive. The thermal stability depends on the internal high energy explosive when the heating rate is relatively low. The thermal stability is similar with the single insensitive explosive when the heating rate is relatively high. Therefore, only at higher heating rate, this kind of composite charge structure can improve the explosive power and thermal stability. The effects of charge constructions on energy output were studied by experiments such as cylinder test and plane flyer test and computational simulation which can reflect the detailed composite structure’s contribution to detonation driven ability of the explosive.50mm cylinder tests were simulated by FEM software. It is showed that the composite charge explosives have lower sensitivity, higher energy out, lower cost and higher utilization efficiency than single explosives. The empirical equation obtained from the simulation can guide the design of the charge contracture. Plane flyer tests were also investigated. The formula obtained after introducing the detonation velocity of both explosives and the height of the grain can predict the energy out of composite charge explosives. In the meantime, the propagation of detonation wave in the composite charge structure and the couple effects on the flyer driven of the high explosive and insensitive explosive were analyzed. The relationship among effective explosive volume, detonation velocity and energy output was revealed. Research showed that the plane detonation wave would change into convex wave by series using of high explosive and insensitive explosive. The prediction of the plane range and the lagging time from the center section to the edge of the waveform has guiding significance for explosive experiment design.The internal flow field of the composite charge structure was analyzed by Whitham method and polar curves graphic method. The corresponding change situation between detonation velocity and curvature of different dimension charge structure were analyzed and explained. And the interactions of the curved surface detonation waves formed by multipoint detonating were analyzed.The composite charge structure was optimized by the method of neural net in view of the sensitivity and energy output.