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An increase in temperature of an explosive will lead shock sensitivity to change, which affects explosive safety. Therefore, a study of the effect of temperature on the shock initiation of explosives is of great significance. We carried out a series of tests on explosive-driven flyer-initiating heated RDX-based aluminized explosives (61 wt % RDX, 30 wt % Al, 9 wt % binder) and the temperature and input shock pressure of the explosives were controlled accurately during the tests. The pressure histories at different depths inside the explosives were measured by using manganin pressure gauges, and the effect of temperature on detonation wave growth was analysed. The ignition and growth reaction model, some parameters of which rely on temperature, was used to simulate the shock-initiation processes.The relationship between the model parameters and the temperature were obtained from the experimental results. The run distance to detonation as a function of the initial input pressure in a temperature range, the Pop plot, and the reaction degree of the explosives were determined. For the RDX-based aluminized explosives, binder softening and the increasing sensitivity of RDX are the two main reasons that change the shock sensitivity. For 25°C-110°C, the shock sensitivity decreases with an increase in temperature, mainly because of binder softening. However, for 110°C-170°C, the shock sensitivity increases with an increase in temperature, which depends on the increasing sensitivity of the RDX. Figure 5. Calculated and measured pressure histories of different temperatures at different depths with 10-mm thick PTFE separator. (a) 42 � C, (b) 100°C, (c) 170°C. Effect of Temperature on Shock Initiation of RDX-Based Aluminized Explosives Propellants Explos. Pyrotech. 2019,

Laser-driven flyer technology is a new dynamic high-pressure loading approach for accelerating metal as a high-speed flyer. The flyer velocity can be effectively increased using a multi-pulse laser. However, the effect of interactions between the multi-pulse laser and the metal foil on flyer formation is not clear. Based on atomic-scale dynamics combined with the two-temperature model, this paper models for the first time the entire process of using a multi-pulse laser to form a high-speed flyer. It was found that the velocity, thickness, and integrity of the flyer are different for multi-pulse than for single pulse. For a fixed number of pulses, the velocity and integrity of the flyer can be increased by appropriately increasing the delay time. However, if the delay time is too long, the shock wave generated by the second pulse will cause the flyer to suffer from secondary shock loading, and the integrity of the flyer is destroyed. If the delay time between each laser beam is fixed, the energy of each beam and the resulting pressure of the shock wave can be reduced by increasing the number of pulses. In this case, the flyer does not undergo strong impact loading and the integrity of the flyer is improved. The shock wave caused by laser pulse can result in the crystal transformation from FCC to BCC or HCP, which enhances the formation of flyer. The results of this study are important for understanding the dynamic response of a metal subjected to a multi-pulse laser and for developing laser-driven flyer technology.

Understanding the shaped‐charge jet‐initiation mechanism of covered explosives and the effect of explosive temperature is important for ammunition safety. We devised a method of using a shaped‐charge jet‐penetrating cover to shock‐initiate heated explosives. This method achieves uniform temperature control of explosives via heating the upper and lower ends and preserves heat on the side of the explosive charge. We experimentally tested the method on hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX)‐based aluminized explosives (61 wt.% RDX, 30 wt.% Al, 9 wt.% binder) at different temperatures and cover thicknesses. The jet‐penetration behavior and explosive detonation‐wave growth were observed via X‐ray photography, and the effect of explosive temperature on jet initiation was analyzed. A numerical model of the shaped‐charge jet‐initiating explosive was set up by considering the temperature change of the explosive and analyzing the detonation‐wave growth and initiation thresholds of different explosive temperatures under jet shock initiation. Under a thin cover, the explosive showed prompt impact initiation by the jet; the initiation occurred very near to the explosive surface. However, for a thick cover, the explosion was initiated by a bow wave formed at a certain distance from the upper surface of the explosive, and a retonation wave was observed. The temperature of RDX‐based aluminized explosives affects the two jet‐initiation mechanisms. The shock sensitivity of the explosives to the jet decreased with increasing temperature, but the shock sensitivity increased when the temperature exceeded a certain value. A simulation method was established that can be used to predict shaped‐charge jet initiation at different explosive temperatures. We obtained the relationship between the cover thickness and run‐to‐detonation distance under jet shock initiation, which provides a theoretical basis for safety analysis and evaluation of a warhead charge that is attacked by a shaped‐charge jet.