Abstract:In order to study the aluminum-water reaction characteristics of PVA-nAl/HTPB， the PVA-nAl/HTPB composites were prepared by dispersing nAl/HTPB in the polyvinyl alcohol （PVA）， which was obtained by physical cross-linking method. In order to explore the aluminum-water reaction mechanism， the aluminum-water reaction characteristics of the polyvinyl alcohol-nAl/HTPB with 0.1 mol·L^-1 NaOH solution at different temperatures （25， 40， 55， 70， 85 ℃ and 100 ℃））were investigated and the residue after the aluminum-water reaction were characterized. The results show that the maximum hydrogen production and rate of PVA-nAl/HTPB is 76 mL·g^-1 and 80 mL·g^-1·min^-1， respectively， which is higher than that of PVA-nAl. The product of the aluminum-water reaction is aluminium oxyhydroxide （AlO（OH））.

Abstract:In order to increase the energy of the secondary reaction of composite explosives， the novel composite oxidant ammonium perchlorate （AP）-lithium perchlorate （LiP） was prepared by solvent evaporation method. Scanning electron microscope （SEM） and X-ray diffractometer （XRD） were used to test and characterize the morphology， and crystal structure of the sample. The thermal decomposition properties of the samples were analyzed by differential scanning calorimetry （DSC）. The underwater explosion power parameters of three polymer bonded explosives （PBXs） containing composite AP-LiP， mechanical mixture AP-LiP and AP were evaluated by electrometric method. The results show that， for composite AP-LiP， the crystal morphology is fairly regular， the crystal surface is smooth， the particle size distribution is fairly uniform， and no agglomeration is observed. Composite AP-LiP has a high degree of crystallization and a fairly complete crystal structure. The thermal decomposition performance of composite AP-LiP is better than that of mechanical mixture AP-LiP. The underwater explosion results show that， compared with the AP-containing PBX， the shock wave energy， bubble energy， and total energy of underwater explosion of PBX containing composite AP-LiP increase by 0.098-0.154， 0.254 MJ·kg^-1 and 0.352-0.408 MJ·kg^-1 respectively， and the energy decays slower as the distance increases.

Abstract:Metastable intermolecular composites （MICs） have the advantages of ultra-high reaction rate， high bulk energy density and micron critical reaction propagation size. They show broad application prospects in military fields such as micro energetic devices and rocket propellants. Nano Al/CuO energetic composite films are one of the research hotspots in the field of metastable intermolecular composites. They are prepared by vapor deposition， compatible with the micromachining process of energetic micro electro mechanical systems （MEMS）， and have great application prospects in integrated energetic devices. The preparation， thermal properties， combustion properties， reaction kinetics， the effect of transition layer on the properties of Nano Al/CuO energetic composite films， energetic devices （igniters） and their application technology are reviewed， and the development direction of Nano Al/CuO energetic composite films is prospected.

Abstract:The hydrodynamic software FLUENT was used to study the drag coefficient of fragments with different initial velocities （≤2500 m·s^-1） and altitudes （≤20 km）， and the velocity attenuation model of fragments with different altitudes was corrected Then the accuracy of the corrected model was verified by the corresponding velocity attenuation characteristic tests with low atmospheric pressures. The results show that the calculated results of spherical fragments with an initial velocity of 700 m·s^-1 and cuboid fragments with an initial velocity of 1000 m·s^-1 using the corrected velocity attenuation model are in good agreement with the experimental results that the errors are less than 5%， and the calculation accuracy of the modified velocity attenuation model is about 10% higher than that of the original model. The corrected velocity attenuation model of fragments can be used to calculate the influence of the drag coefficient， which is varied with the altitude， on the velocity attenuation coefficient of fragments， to improve the calculation accuracy of the fragment velocity， and to further improve the accuracy of the power evaluation of the fragment warhead.

Abstract:In order to study the influence of structural parameters on characteristics of fragments from warheads with a composite charge， AUTODYN-3D finite element calculation software was used. Next the propagation of detonation waves and shell breaking process of warheads were compared and analyzed， under the central single-point initiation and the internal and external simultaneous initiation. Then the influence of shell thicknesses and central charge diameters on the average mass and velocity of fragments from warheads was obtained. The calculation results show that， with the increase of shell thicknesses or the decrease of central charge diameters， the average mass of fragments under single-point initiation increases more times than that under internal and external simultaneous initiation， and the difference in power output of warheads between those two initiation modes becomes more significant. The static explosion test results show that the average velocity of fragments， shock wave overpressure， and the number of witness target holes under internal and external simultaneous initiation increase 27.1%， 31.4%， and 39.3%， respectively， compared with those under single initiation. The test results are in good agreement with the calculation results.

Abstract:In order to investigate the influence of the pitch angular velocity on the penetration trajectory of projectile penetrating into multi-layered target， a large amount of experimental and simulation from literature was analyzed. In the paper， LS-DYNA finite element software was used to simulate the projectile penetrating into multi-layered slabs with or without considering the pith angle velocity. Data obtained in the simulations， like the paper studied the pith angle， landing time， landing speed， landing offset， angle of attack，landing angle， fuse overloading and etc.， were compared with the experimental results. The results show that the numerical simulation was agreed well with the corresponding experimental data， when the pitch was taken into consideration. The influences of pitch with different values and directions on the trajectory of projectile penetration into multi-layered reinforced concrete slabs were analyzed. It shows that， under the same value， the positive pith angular velocity had a greater influence than the negative one. Secondly， in order to ensure that the projectile explode in the target building， the value and direction of the pith angular velocity of the projectile must be controlled between -627°·s^-1 and 427°·s^-1.

Abstract:Numerical simulation was carried out to study the reaction evolution of explosive charge under weak stimulation and the effect of confinement conditions on its explosion reaction. Based on the multi-media arbitrary Lagrangian-Eulerian method and fluid-structure coupling technique， the numerical simulation of the reaction evolution growth of constrained charge and its interaction with the shell after local ignition were realized. In order to simulate the process from slow burning to violent explosion， a phenomenological model of explosion evolution growth was established. Based on the central ignition experiment of the strongly constrained spherical charge， a series of simulations were conducted and the influence of confinement conditions on the reaction pressure growth process of PBX-2 explosive was analyzed. The results show that the peak value of reaction pressure increases with the increase of shell strength or thickness. When the thickness of the steel shell increases from 5 mm to 20 mm， the peak value of the pressure increases from 163 MPa to 1357 MPa， and the process of pressure increase varies greatly. However， with the fracture and disintegration of the shell， the transformation from explosion to detonation of the explosive charge is restrained.

Abstract:Aiming at the development and problems of high-strength energetic structural materials （ESMs）， the characteristics， static mechanical behaviors and dynamic mechanical behaviors of high-entropy alloys （HEAs） were summarized and analyzed. The assumptions， potential and challenges of HEAs as high-strength ESMs were proposed and verified from the perspective of both theoretical and experimental aspects. It was found that HEAs had the basic features of “free composition design”， “simple crystal structure with strong lattice distortion” and “high strength and hardness”. At the same time， both static and dynamic mechanical behaviors of HEAs could be adjusted in a wide range by means of process adjustment and composition design. All the above features indicated that HEAs had the potential advantages to be used as high-strength ESMs in terms of workability， high strength， and rapid oxidation to release energy. Existing experimental results also confirmed the application potential of HEAs ESMs. Finally， the challenges faced by the research of high-entropy alloy ESMs and the priorities of future research， such as high-throughput experiments and simulations， researches on dynamic mechanical behaviors and preparation for large-scale samples， were raised based on the intrinsic features of HEAs and previous experimental results.

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Abstract:In order to prevent the spacecraft from being damaged by the high pyroshock during the action of the pyrotechnic separation nuts， a metal rubber vibration isolator（MRVI） was used to suppress the pyroshock response caused by the impact of the piston in the separation nut. Three kinds of MRVIs with different stiffness were installed at the end of the piston movement in the separating nut， and the shock response spectrum（SRS） in the frequency domain of 500 Hz to 10000 Hz was analyzed. The results show that the pyroshock suppression effect of the MRVI mainly occurs in the frequency band above 3000 Hz， and the pyroshock suppression effect in the frequency band above 5000 Hz is the most significant. The maximum acceleration response after installing a small-stiffness MRVI is reduced from 1330 g to 852 g， and the maximum reduction in analysis frequency domain is 675 g@5993 Hz. The maximum acceleration response after installing a medium-stiffness MRVI is reduced from 1530 g to 1251 g， and the maximum reduction in analysis frequency domain is 539 g@9514 Hz. The maximum acceleration response after installing a large-stiffness MRVI is reduced from 1697 g to 1416 g， and the maximum reduction in analysis frequency domain is 538 g@8476 Hz. The use of MRVI achieves a better pyroshock suppression effect， and provides a viable method for the pyroshock reduction design of the pyrotechnical actuation devices.

Abstract:To study the correlation between the packed density of nonmetallic spherical spacers （NSS） and its suppression of propane explosion， a newly designed constant-volume combustion cylinder combined with high-speed schlieren photography was employed. The explosion experiments of propane-oxygen pre-mixtures with different equivalence ratios（1，1.5 and 2） were conducted in cylinders with different packed densities of NSS （21.9 kg·m^-3，38.7 kg·m^-3 and 45.1 kg·m^-3）. The effect of packed densities of NSS on maximum explosion pressures， total heat loss， flame tip velocities， flame propagation characteristics and turbulence in cylinders with different equivalence ratios of propane-oxygen were analyzed in detail. The results show that NSS has suppression effect on the maximum explosion pressure， and has promotion effect on the flame propagation process. When the packed density of NSS is 45.1 kg·m^-3， the maximum explosion descending rate and heat loss in cylinders reach maxima， while the peak flame tip velocity ， the maximum tip velocity difference between two points and the turbulence enhancement factor in cylinders are relatively small， which indicates the best explosion suppression performance of NSS.

Abstract:3， 4-dinitropyrazole（DNP）， a new type of smelt-cast matrix explosive， is a kind of high energy matrix with great application potential. The impact Hugoniot relationship of explosive is the basis to investigate its impact initiation characteristics. For this reason， the pressure comparison method was adopted in this study. Plane wave generators were selected to act the designed loading. The post-shock pressure of DNP explosive and LY12 aluminum samples under nine shock pressures were measured by manganese-copper piezoresistivity gauges. By calculating the experimental data， the velocity （D） of the shock wave and the velocity u of the particle under different pressures were obtained. The D-U relationship of the DNP explosive in the range of 3.7~14.4 GPa was obtained by fitting. The results showed that the Hugoniot relationship of the DNP explosive in the range of 3.7~14.4 GPa could be approximated as a straight line in the D-U plane. The post-wave state of DNP explosive under the action of shock wave was defined， which provided a reference for further study of impact ignition and initiation of DNP explosives. In addition， the influence of polytetrafluoroethylene packaging of manganese-copper piezoresistance gauges on the experimental test results was analyzed. The systematic error caused by packaging was effectively eliminated through theoretical analysis and reasonable interpretation of test signals.

Abstract:Burning damage technology is an important research area in energetic materials and damage. The research in burning damage technology was mainly reviewed and summarized from three aspects： the formulation design and application of incendiary agents， the damage theory and technology of burning thermal radiation， and the burning damage assessment technology. Problems such as insufficient burning damage effectiveness of incendiary agents， single process of parameter characterization in thermal radiation model and incomprehensive burning damage assessment method were pointed out. The future research emphases on burning damage technology include incendiary materials with high densities and high calorific values，the structure-effect relationship of incendiary agent charges，testing technology for key model parameters represented by the fireball temperature， correction and optimization of thermal radiation damage models， and the accurate assessment method of thermal radiation damage effect under the coupling effect of multiple damage elements in the damage field.

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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:With the deepening and development of the concept of long-range operations， long-range strike of missile has become an indispensable part of modern warfare. Therefore， the damage assessment of target hit by missile warhead has been the focus of damage research in recent years. Research of damage assessment in the process of missile warhead striking the target are summarized from four aspects： damage assessment model of target， main subjects in damage process， damage of classified targets， and methods of damage assessment， respectively. Problems such as non-standard judgment of damage degree， unclear relationship of damage mapping and inaccurate solution of damage probability in current stage are pointed out. According to the insufficiency of current study， some suggestions are proposed for the research in the future， which can provide reference for the investigations in the related fields.