Abstract:

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 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: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.

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: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 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 study the energy release characteristics of Al/Mg/CuO reactive shells， the images of broken process of reactive shells were observed by an ultra-highspeed rotating-mirror camera， and the shock wave overpressures of varying-sized test bombs were measured by shock wave test system. The reaction time of reactive shell under explosion loads and the effects of particle sizes of reactive materials on shock wave overpressures were analyzed， then the variation of shock wave overpressures with scaled distances was obtained. The results show that reactive shells could take part in explosive reaction and release energy in a few microseconds after detonation reaction. The shock wave overpressures are enhanced and the fireball duration increases more than one time within a scaled distance of 2.52-3.15 m∙kg^-1/3.The overpressure of reactive shell with particle size of 7 μm is 13.3%-14.4% higher than that of reactive shell with particle size of 20 μm，which indicates that reactive materials with smaller particle size can take part in explosive reaction more easily. Compared to bare charges and aluminum shells， the overpressures and impulses of reactive shells rise significantly， increasing 6%-32% and 13%-38% respectively within scaled distances of 2.1-8.4 m∙kg^-1/3.

Abstract:In order to study the influences of ZrH₂ onto mechanical properties and damage performances of Al/PTFE， both cylinder and liner specimens of Al/ZrH₂/PTFE， Al/PTFE and pure PTFE were prepared by cold-pressing sintering process. The mechanical properties， impact sensitivity and damage efficiency of the three materials were contrastively studied by the tests of quasi-static compression， drop-weight impact and high-speed target impact. The experimental results showed that all three kinds of PTFE-based materials exhibited elastic-plastic mechanical behaviors and strain hardening effects. Adding a mass fraction of 10% of ZrH₂ into Al/PTFE reactive material improved its yield strength and failure stress to 22.2 MPa and 93.3 MPa， respectively， increased its ignition excitation energy by 1.93 J， and participated in the reaction through activation and decomposition to ensure that its energy release level was not weakened. The two kinds of energetic liners can produce collision energy release reaction and perforation/pore enlargement sympathetic effects during its impacting process， and formed the perforation pattern of petal valgus. Compared with inert damage element， the reactive material greatly improved its hole-enlargement ability by the impact-reaction double damage effect. The introduction of ZrH₂ into Al/PTFE reactive material can further enhance the damage efficiency of the material.

Abstract:To explore the liquid components of high-potential Fuel air explosive（FAE） with better damage power， taking the traditional typical fuel （propylene oxide） as reference， polymethoxy dibutyl ethe（BTPOM_n）， polymethoxy dimethyl ether （DMM₂）， 1-butanol and 2-butyl alcohol were selected as research object. A pressure testing system， high-speed camera and infrared thermal image were used to record the experimental data. The cloud explosive characteristics of the 5 fuels with 18g RDX as central burster charge and 160g TNT as secondary explosive were studied. The results indicated that the critical initiation energy of the DMM₂was higher than that of the other fuels. The relationship of the damage radius of thermal radiation among 5 fuels was as follows： propylene oxide （18.9 m）＞2-butyl alcohol （16.6 m）＞1-butanol （16.0 m）＞DMM₂ （15.6 m）＞BTPOM_n （12 m）. The damage effects of 5 fuels on people and buildings were evaluated by the PROBIT equation， and the results showed that the damage effects of 1-butanol and 2-butyl alcohol were better than those of BTPOM_n and DMM₂， and the propylene oxide had the best damage effect.

Abstract:The development trend of miniaturization of modern energetic devices puts forward higher requirements for the energy density of pyrotechnic agents. In addition， as the concept of sustainable development is widely recognized and accepted， the toxicity of lead-containing explosives has increasingly aroused people"s concerns. For a long time， copper azide has been subject to extremely high sensitivity and therefore has not been widely used in weaponry and civilian blasting equipment. However， due to its green and high energy density characteristics， copper azide has attracted researchers" interest in recent years. The research progress of energetic materials based on copper azide in and abroad is summarized， mainly including the following perspectives： theoretical research on crystal structure level， synthesis methods of different ways， design and preparation of composite materials， practical application of microcharges and its performance test. As a kind of energetic material which has attracted attention in recent years， copper azide， has apparent advantages and disadvantages. The critical point to realize its potential application prospects lies in： theoretically grasping its crystal structure and reaction mechanism more deeply； making up for its overly sensitive defects while giving play to its advantages of high energy density from the perspective of structural design； to understand its performance parameters more systematically through experiments and simulations； developing advanced synthesis methods and charging technologies to meet the requirements of Micro-Electro-Mechanical System （MEMS） pyrotechnic devices for precise and reliable charging of energetic materials.

Abstract:Metal oxide is a type of ionic compound in which metal cations and oxygen anions are arranged into different crystal structures through ionic bond. The d-shells of some metal oxides are not completely filled wtih various unique properties， such as wide band gap， high dielectric constant， active electron transfer ability and excellent conductivity， etc. So they are widely used in the catalytic field. The current research status of thermal decomposition of ammonium perchlorate catalyzed by four different types of metal oxide semiconductor materials， such as single metal oxide， composite metal oxide， doped metal oxide， and supported metal oxide were introduced， the catalytic mechanism and factors affecting the catalytic effect were discussed. For the P-type metal oxide semiconductor materials， the narrower the band gap ， the lower the Fermi energy level， the higher the escape energy， and the greater the catalytic effect. For the N-type metal oxide semiconductor materials， the wider the band gap， the higher the Fermi energy level， the lower the escape energy， and the better the catalytic effect. In order to make full use of the advantages and overcome the defects of metal oxides， impurity elements are often introduced into metal oxides to form ionic lattice defects and create new local impurity energy levels to change the electronic transition， so as to improve the catalytic performance of metal oxides. Whether composite metal oxide or supported metal oxide， there is a positive synergistic catalytic effect on AP. The development of porous nanotube P-type metal oxides， doped metal oxides， and supported metal oxide materials with small band gap is still a major concern. Exploring the core-shell composite materials based on ammonium perchlorate， P-N junction metal oxide semiconductor catalytic materials， and revealing the migration law of carriers between the two kinds of semiconductors P-N interface are expected to be a new way to improve the catalytic efficiency.