Abstract:To study the thermal response of two new DNAN-based aluminized explosives RB-2X（DNAN/HMX/Al/binder） and RM-2X（DNAN/HMX/NTO/Al/binder）， small-scale cook-off experiments and simulations of RB-2X at a heating rate of 1.0 K·min^-1 and RB-2X at heating rates of 1.0 K·min^-1 and 0.5 K·min^-1 were conducted. The numerical simulation used multi-component grid cell calculation method and considered the air gap formed by cooling and contraction of fused cast explosive. The thermal response of explosives were analyzed. The comparisons of ignition time between simulation and experiment show that the ignition time deviation of RB-2X explosive is 1.13%， and the maximum deviation of RM-2X explosive is 5.63%. The influence of the air gap between the explosive and the inner wall of the bomb on ignition time was also analyzed. The results show that the delay time increases gradually with the increase of gap width， and when the air gap expands to 0.75 mm， the delay time is stable at 90 s， indicating that the air gap has a significant influence on the explosive ignition time. The thermal response of large-scale cook-off bomb with RM-2X explosive was predicted. The results show that the temperature at center point can be significantly reduced at ignition by increasing of ammunition size and heating rate. The state of DNAN changes from total melting to solid-liquid coexistence.

Abstract:In order to precisely validate the parameters of detonation reaction rate model of explosives， a HMX/TATB based explosive PBX-1 was the research subject， and the mushroom test was conducted to study the corner-turning performance of explosives with various detonation propagation diameters. Then the mushroom test was simulated by LS-DYNA program with the three-term ignition and growth model calibrated by Lagrangian gauges measurements. The accuracy in calibrated parameters of the reaction rate model was validated by observing the growth and propagation of detonation waves and by comparing the corner-turning parameters. The comparison between experiments and numerical simulations shows that， the mushroom test can reflect the discrepancy of detonation growths of detonation waves in different directions. Finally， it was proved that the parameter validation of the reaction rate model of explosives is feasible by Mushroom test..

Abstract:To obtain the influence of submillimeter-sized gap or cushion on the behavior of flyer driven by the detonation of a triaminotrinitrobenzene（TATB）-based explosive， the precise detonation tests with submillimeter-sized gap or cushion were designed. The velocity histories of flyer driven by the triaminotrinitrobenzene（TATB）-based explosive and influenced by the submillimeter-sized gap or cushion were recorded by a laser interferometer （photon Doppler velocimeter）. The results show that the jump-up velocity of the flyer with the influence of submillimeter-sized cushion is lower than the case of flyer attached to explosive， but the final velocity is higher （around 20 m·s^-1 or 1% of the final velocity）. While the influence of submillimeter-sized gap is greater than that of submillimeter-sized cushion that， the final velocity is 50 m·s^-1 （2%） higher than the case of flyer attached to explosive. Simultaneously conducted numerical simulations show that both the point and line initiation conditions do affect the velocity history of the flyer， and the final velocity increases with the influence of submillimeter-sized gap and with either initiation condition. The theory analysis indicates that the introduction of submillimeter-sized gap between flyer and explosive results in weaker interaction between detonation products and flyer for the isentropic expansion of detonation products， and then leads to less entropy increasement of the system， higher energy for driving the flyer， and higher final velocity of the flyer. Additionally， different gap sizes result in different influences as the dominant mechanism varies.

Abstract:In order to improve the utilization rate of explosive energy and reduce the mass of welding explosive， it was proposed to use self-restrained explosive to carry out explosive welding research. T2/Q345 weldability window was obtained through theoretical calculations. T2 copper and Q345 steel were respectively used as the substrate and flyer layers， and honeycomb explosive of two layers was used as welding energy to carry out T2/Q345 explosion welding research. The results show that the T2/Q345 composite plate obtained by honeycomb explosive of two layers with self-restrained capability has good bonding performance. Compared with single-layer explosives with corresponding detonation velocities of 2505 m·s^-1 and 3512 m·s^-1， T2/Q345 explosive welding obtained by honeycomb explosive of two layers can save 54.4% and 31.4% explosive by weight， respectively. The honeycomb explosive improves the utilization rate of explosion energy converted into kinetic energy of flyer layer. In addition， with the increase of collision point distance， the interface of the T2/Q345 composite plate changes from flat to wavy.

Abstract:Ammunitions might experience safety threats of high-temperature heating， high-speed fragment impact， and their combined effects in battlefield. In order to investigate the reaction phenomenon of insensitive explosive PBX-C04 under high-speed impact and the effects of high-temperature and booster charge on this reaction phenomenon， the insensitive explosive safety experiments under high-speed fragment impact were carried out， and the influences of high-temperature and insensitive booster charges（HNS） were considered. Based on the air overpressure， witness plate wreckage and chemical-physical analysis of remained explosives on the scene， the explosive reaction levels of PBX-C04 was assessed comprehensively， and the influences of high temperature and booster charge were studied. The results show that PBX-C04 at room temperature exhibits excellent safety characteristic under high-speed fragment impact， it merely reacted to burning when impacted by a fragment with velocity up to 1970 m·s^-1. When the booster charges of HNS was included， the reaction levels of PBX-C04 correspondingly deteriorated into deflagration. However， when heated to 200 ℃ before impact test， the high-speed impact safety of PBX-C04 equipped with booster charge deteriorated remarkably into detonation.

Abstract:To investigate the coupling effect and propagation law of shock wave for underwater array explosion with multiple charges. The shock wave parameters of group charge， two charges and four charges were measured by underwater explosion test. The influence of charge quantity and array distance on peak pressure， impulse and loading time of shock waves were analyzed and revealed the relationship beween array explosion shock wave parameters and distances. The results showed that the shock wave （symmetrical center line） can be superimposed in the focusing direction for two-charge explosion. The shock wave pressure intensity increased by 22.8%-55.4% in the scale distance of 2-6 m·kg^-1/3， and the gain increased gradually with the increase of propagation distance. For four-charge array explosion， the peak pressure of the shock wave in the focusing direction was close to that of group charge. For the same explosion points and layout of the array explosion， the impulse and shock wave loading time can be improved by increasing the array distance. The loading time of shock wave pressure increased with the increase of charge quantity and array distance. For two-charge and four-charge explosion， the peak pressure and impulse of multiple shock waves were still consistent with explosion similarity law， but the loading time of shock wave pressure was not.

Abstract:To study the influence of RDX-based metallized explosive components on detonation process，the detonation reaction zone parameters of RDX-based metallized explosives were studied by the interface particle velocity history using photonic Doppler velocimetry （PDV）. Two kinds of RDX-based metallized explosives were granulated， one composition incorporates aluminum （RDX/AP/Al）， and the other incorporates hydrogen storage alloy （RDX/AP/Al/B/MgH₂）. The metallized explosives were initiated by detonation wave， and the detonation reaction zone parameters were analyzed and compared with those of phlegmatized RDX. The results show that the addition of AP/Al component reduced the CJ detonation pressure of phlegmatized RDX from 25.8 GPa to 20.1 GPa. In addition， the detonation reaction zone time （53.6 ns） and length （0.29 mm） of metallized explosives were both higher than those of phlegmatized RDX （24.3 ns， 0.15 mm）. The addition of B/MgH₂ further increased the detonation reaction time （58.0 ns） and length （0.30 mm） of the explosive. The addition of high-energy metal fuel reduced the output pressure of explosives， but increased the detonation reaction zone time and length of explosives.

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