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Abstract:The blend of nitrocellulose (NC) and polyethlene glycol (PEG) was prepared by solution blending method. The interaction between the two components PEG and NC, and the microscopic structure of the blend were characterized via infrared spectroscopy and polarizing microscope. Results show that there is a strong interaction between NC and PEG, and PEG fragmentary crystallites disperse in the blended system. The mechanism of the interaction between NC and PEG was studied by molecular dynamics simulation, and the microscopic structure and density distribution were obtained by the mesoscopic dynamic simulation. The above two simulations have a good accordance with the experimental results. Molecular interaction and microstructure of NC/PEG system can be characterized by molecular dynamics and mesoscopic dynamic simulation.

Abstract:Energy characteristics of the composite modified double-base (CMDB) propellant, hydroxy terminated polybutadiene(HTPB)propellant, nitrate ester plasticized polyether (NEPE) propellant and glycidyl azide polymer (GAP) propellant containing dihydroxylammonium 5, 5′-bistetrazole-1, 1′-diolate(TKX-50) were calculated by CAD system software according to military standard GJB/Z84-1996 under the standard condition(p_c/p₀=70:1). Results show that theoretical specific impulse of the TKX-50 monopropellant is 2623.7 N·s·kg^-1and 6.5 N·s·kg^-1higher than that of the RDX monopropellant. TKX-50 is a better replacement of RDX in CMDB propellant. When the substitution of TKX-50 for AP in HTPB propellant and AP and HMX in GAP propellant, theoretical specific impulses for TKX-50-based HTPB propellant and TKX-50-based GAP propellant exist a optimal value of energy. When the substitution of TKX-50 for AP and HMX in NEPE propellant, theoretical specific impulse of TKX-50-based NEPE propellant increases at first, then decreases, and then increases, and the maximum increase can reach 20.4 N·s·kg^-1.

Abstract:To study the aging mechanism of HTPB(hydroxyl-terminated palybutadiene) propellant, the quantum chemistry method was used to calculate the bond energy of chemical bond of HTPB-TDI(toluene diisocyante) curing system, and transition states of possible four oxidative cross-linking reactions occurring in the aging process of HTPB propellant were investigated. Results show that the bond energy of C—O bond connected with CH₂ group is minimum. The energy is determined as 244.95 kJ·mol^-1. The rupture of the C—O bond in the aging degradation process easily occurs. The activation energies of possible four oxidation linking reactions are all smaller, and less than the energy needed for HTPB-TDI curing molecular degradation, indicating that oxidation linking reaction is the primary cause of HTPB propellant aging. Among them, the activation energy of ternary-epoxy reaction is minimum and its value is 12.59 kJ·mol^-1.

Abstract:To study the forming regularity of combustion residue caused by the deviation of web size of gun propellant, the web size of oblate propellant was measured by a spiral micrometer and the distribution rule of web size was obtained by statistical analysis. Using propellant form function of composite charge, the distribution rule of web size was converted to propellant form function, and then the relationship between distribution of web size and combustion residue was investigated based on the classical interior ballistic models. Results show that the deviation of web size exists in gun propellant, and the distribution rule of web size conforms to normal probability function. The propellant with large web size can not be burned out in chamber and form combustion residue. The deviation value of web size of oblate propellant is 0.10 mm, and 0.2% of the propellant charge will become combustion residue when firing. When the deviation value of web size over 0.02 mm or expected value greater than or equal to 0.29 mm, part of the propellant charge will change to combustion residue, and the amounts of residue increases with the increasing of expected value or deviation of web size of propellant.

Abstract:In order to predict the initial velocity of multilayered spherical fragments warhead in detail, AUTODYN was utilized to simulate the process of explosively drive aimed at the typical warheads, filled with cylindrical charge and multilayered spherical fragments. It′s found that velocities of fragments varied regularly in circumference on each layer and the mean velocity of inner fragments is bigger than that of outer fragments, especially in the case of more layers and less circumferential fragments. Then, a model was established by theoretical derivation based on momentum theorem and Gurney′s hypothesis as well as the data from simulation. The model gives three types of velocity to characterize the initial velocity field. The three types of velocity is as follows: average initial velocity of fragment in any layer, maximum and minimum initial velocity of fragments. The results predicted by the model go well with test results.

Abstract:The numerical simulation of lethality enhancement device of explosively drive reactive rods was carried out to investigate the effect caused by the arrangement mode, arrangement radius and buffer materials. Results show that the collision between reactive rods can be effectively avoided and the stability significantly enhanced when the angle between the radial arrangement of two layers is 11.25° and the radiuses of outer and inner layers are < 85 mm and >37 mm, respectively. The pressure that inner layer rods bear decreases with the increase of arrangement radius. All of the polystyrene, polyethylene and polyurethane can be used as buffer material in the lethality enhancement device, but the scope of velocity of these rods is smaller, the convergence is faster and the spatial distribution is better when polyurethane is used.

Abstract:Tungsten alloy was adopted as the jacket of PELE widely up to now, but it had a series of disadvantages, such as inadequate obdurability, uncontrollable shape and amount of fragments, imperfect lateral damage effect, and so on. To solve the problem, tungsten fiber composite was brought forward to produce penetrator with enhanced lateral effect(PELE) jacket, and numerical simulations was carried out on the penetration process by PELE with tungsten fiber composite jacket. Results show that the penetrating performance and lateral damage effect of PELE with tungsten fiber composite jacket are superior to those of PELE with tungsten alloy jacket. Further, PELE with tungsten fiber composite has better damage performance, when the diameter of tungsten fibers is between 0.5-1 mm, the volume fraction of tungsten fibers is 40%-60%, and the binder phase is ferro-nickel alloy.

Abstract:An annular jet model was proposed to improve the turbo-charge and anti-drag effect of base bleed in tail flow field. Two-dimensional axisymmetric Navier-Stokes equations was computed using a finite volume scheme, and the tail flow field of base bleed was simulated. The simulation results were validated with experimental data well. Based this, the influence annular jet upon the tail flow field of base bleed was investigated. Results show that the base pressure of annular jet model is always higher than that of circular jet model with the increase of the injection parameters. Compared with circular jet, annular jet can weaken the strength of annulus recirculation. It makes bleed gases flow into the shear layer more easily and can avoid the occurrence of the ejector. The smaller the distance between the annular jet and the base edge, the better the benefits of base bleed.

Abstract:The blast resistant characteristics of anti-explosion container built-in cylindrical shells/group spring and aluminum foam sandwich under 3 kg TNT explosion impact loading were numerically simulated using LS-DYNA explicit non-linear dynamic finite element analysis (FEA) program. Results show that the container interior pressure load reveals the multiple pulsating characteristics. The specific impulse load experiences several step rise. The cylindrical shell/group spring structure can deliver energy to absorbing energy aluminum foam sandwich more evenly and makes the energy absorption efficiency of aluminum foam enhance obviously under the presime to guarantee that the plastic deformation does not occur in the inner cylinder of anti-explosion container. The quantitative analysis of energy conversion and absorption of each materials and all parts in anti-explosion container shows that alumium foam sandwich can transfer and absorb impact energy gained from the internal cylinder steel plate by the foam of unloading kinetic energy and transmission stress wave.

Abstract:Using dichloro-glyoxime, sodium azide and dimethyl formamide (DMF) as primary materials, the 1, 1′-dihydroxy-5, 5′-bistetrazole (1, 1′-BTO) was synthesized. Then, it was reacted with the hydroxylamine hydrochloride to form the target compound dihydroxylammonium 5, 5′-bistetrazole-1, 1′-diolate(TKX-50) with a yield of 73.2%. Its structure was simulated by Gaussian software at the B3LYP/6-31++G level. Results show that there are strong inter-and intra-molecular hydrogen bonds in the solid crystal. These hydrogen bonds effectively improve the density of TKX-50 to 1.918 g·cm^-3. Based on this density, detonation parameters were calculated. The detonation velocity reaches 9698 m·s^-1, the detonation pressure is 42.4 GPa, friction sensitivity is 120 N, and impact sensivity is 20 J.

Abstract:To analyze the jet impact sensitivity of the new high-energy insensitive explosive 2, 6-diamino-3, 5-dinitropyridine-1-oxide(ANPyO), the jet initiation sensitivity test of unconfined explosive ANPyO and 8701 covered by 45^# steel barrier under the conditions of shaped charge with diameter of 56 mm and stand off of 80 mm was performed. The critical thickness of barrier was obtained by Langlie method, the critical head velocity and diameter of jet were calculated by AUTODYN, the critical initiation threshold I_cr was calibrated and comparison of the test results of ANPyO with the test ones of 8701 explosive was carried out. Results show that under the critical detonation, the critical thickness of 45# steel barrier covering 8701 explosive is about 160 mm and for ANPyO explosive is about 68 mm, which reduces by about 57.5%. The critical velocity of ANPyO is 3.7 mm·μs^-1. The head diameter of jet for ANPyO is 4.8 mm. The initiation threshold I_cr of ANPyO is about 32.3 mm³·μs^-2, which is four times than 8701 explosive; revealing that ANPyO is much more insensitive than 8701 explosive, and it is a kind of explosive with low jet initiation sensitivity.

Abstract:The single crystal structure of hexabenzylhexaazaisowurtzitane (HBIW) was determined by X-ray single crystal diffractomater, the characteristics of NMR spectra of HBIW were studied in CDCl₃, acetone-d₆ and DMSO-d₆, respectively, and the molecular structure of HBIW was identified by a combination of 1D (¹H NMR, ¹³C NMR and ¹⁵N NMR) and 2D (gHSQC and gHMBC) NMR techniques. Results show that the crystal belongs to orthorhombic system with space group Pca2(1) and the unit cell parameters a=0.10724(2) nm, b=0.37001(7) nm, c=0.20476(4) nm, α=β=γ=90°, V=8.125(3)×10³ nm³, Z=4, D_c=1.159 g·cm^-3, F(000)＝3024. The chemical shifts of H atoms from high field to low field are assigned to CH on the bridge head, CH₂ bonded to six-membered ring, CH₂ bonded to five-membered ring, CH in six-membered ring and CH in benzene, respectively, while the chemical shifts of C atoms from high field to low field are assigned to CH₂ bonded to five-membered ring, CH₂ bonded to six-membered ring, CH in six-membered ring, CH on the bridge head, and C in benzene. The chemical shifts of N atoms in five-membered ring and six-membered ring ware found at δ =-317.0 and δ =-297.1, respectively.

Abstract:The nitration of toluene was performed through replacing nitro/sulfuricmixed acid with the mixture of nitric acid and N₂O₅ as a nitrating agent. The effects of reaction temperature, reaction time, and concentration of N₂O₅ on the nitration reaction were investigated. The nitration product of toluene was analyzed by gas chromatography, IR spectrormetry and mass spectrometry. Results show that the nitration product is mainly dinitrotoluene (DNT). The optimum nitration reaction conditions obtained are reaction temperature 10 ℃, N₂O₅ concentration 3 mol·L^-1 and reaction time 1 h. The yield of DNT is 100%. The molar ratio of isomerides 2, 4-DNT and 2, 6-DNT is 4.44:1.

Abstract:The way of center explosive charge has an important influence on the fuel air explosive(FAE)devices. Through the determination of high speed photography, the maximum dispersal velocity of the coupling charge FAE device is 408.5 m·s^-1, and its calculation is 412.5 m·s^-1 by LS-DYNA. The deviation is less than 1%, hence, the method is accurate and reliable. Using the same method, the dispersal velocity, explosive cavity and temperature of FAE devices with different center explosive charges were studied. Results show that in case of uncoupling FAE devices, the dispersal velocities in different position have a small amplitude difference, which is about 100 m·s^-1. That is to say the velocity distribution is uniform and the fuel efficiency is high while the explosion cavity radius diminishes about one third in the end and presents a distribution of large in the middle and small in the ends which makes the position of second ignition equipment have more choices. At the same time, compared with the coupling center explosive charge, the explosive cavity temperature for the uncoupled center explosive charges drop quickly, which results in a better safety.

Abstract:To understand the effect of additives on mechanical properties of Comp.B, six formulations of modified Comp.B(B-1, B-2, B-3, B-4, B-5 and B-6)were prepared by addition of thermoplastic elastomer(VP-401 and VP-501) of mass percentage 2%, thermosetting resin polymerized by pentaerythritol and acrylic aldehyde /diethyl sulfate(123 resin/DES) of mass percentage 1% or 3%, hydroxyl-terminated polybutadiene/diphenyl methene-4, 4′diisocyanate (HTPB/MDI) of mass percentage 5% in solidifying coefficient 0.6 and 0.8, respectively. The compression test、Brazilian test and split Hopkinson pressure bar(SHPB) test were performed.The stress-strain curves of modified Comp. B in static compression, indirect tensile and low speed impact were obtained.The elasticity and toughness changes of modified Comp.B were compared and analyzed. Results show that compared with Comp.B, the compressive elastic modulus of B-1 and B-2 explosives increase by 1.49 GPa and 2.28 GPa, respectively. The compressive strength of B-1 and B-2 explosives increase by 6.7 MPa and 6.3 MPa, respectively. Their elasticity and toughness of compress are better than those of Comp.B. When strain rate 50 s^-1. Compared with Comp.B, the dynamic compressive strength of B-3 and B-4 explosives increase by 1.9 MPa and 7.6 MPa, respectively, while the dynamic compressive strength of B-5 and B-6 explosives decrease by 8.33 MPa and 19.47 MPa respectively. Results show that the low speed impact-resistance ability increases for B-3 and B-4 explosives and reduces for B-5 and B-6 explosives.

Abstract:PTFE/Al (polytetrafluoroethylene/aluminum) reactive multilayer films with different thickness and alternating deposition were prepared by a radio frequency magnetron sputtering method using Al as combustible and PTFE as oxidant. The influence rules of sputtering power on the film surface morphology was investigated by atomic force microscope (AFM) and X-ray diffraction (XRD).The appropriate preparation technology of the films was obtained. The mechanical property of PTFE/Al reactive multilayer films was measured by a nano-indentation apparatus. Results show that when the radio frequency sputtering power is 50 W and 150 W, the mean roughness and RMS roughness of PTFE film and Al film obtained are low. When the total thickness of PTFE/Al reactive multilayer films is about 300 nm, in comparison with pure PTFE film and Al film, PTFE/Al reactive multilayer films have higher hardness and elastic modulus: 5.8 GPa and 120.0 GPa, respectively.

Abstract:To improve curing process and to ensure the the launch safety of casting plastic bonded explosives(PBX), the strain change in the process of transition of from liquid to solid for casting PBX was measured by a self-designed-made indirect stress sensor.The effect of curing temperature on the curing stresses of casting PBX was studied. Results show that curing process of PBX includes three stages: the rapid thermal expansion from room temperature to curing temperature, the thermal expansion and crosslinking shrinkage at curing temperature and the shrinkage at cooling stage. The defomation of the test bottles was studied. The casting solidification strain of casting PBX was calculated according to the defomation. The solidification temperature has an abvious effect on defomation of PBX. When the solidification temperature are 100, 90, 80, and 60 ℃, the maximum curing stresses of PBX are 2.14, 0.72, 0.56, and 0.29 MPa, respectively, and the shrinkage stresses of PBX networks are 0.29, 0.25, 0.24, and 0.21 MPa, respectively, revealing that the curing temperature at isothermal curing stage has a greater influnce on the thermal stress and shrinkage stress, the higher curing temperature, the bigger curing thermal stress and shrinkage stress. According to the strain-time curve of the solidification process, the low temperature curing to reduce the curing stress tn the earlier stage and elevanted temperature in the later stage of the curing stress changes smoothly are taken to improve the efficiency of variable temperature curing process.

Abstract:X-ray micro-tomography(X-μCT) was applied to obtain the complete three-dimensional (3D) recordings of TATB-based granules at micrometre resolution. Vortexes are preserved by condensation and encrustation with binder. 3D visualization of structures arrangement and vertical-layer can solve outstanding questions about the nature of vortexes. The morphological features of vortexes such as single-vortex, double-vortex, multi-vortex, vortex-in-vortex in the granules indicate the mode of turbulence development. The dense-layer and vortical-layer reveal the turbulent mass transfer effect of TATB crystals. X-μCT provides a method of non-invasive analysis for probing the very limits of vortexes and insight into condensed vortexes during the emergence turbulence.

Abstract:The reaction kinetics of the GAP/HMDI, GAP/TDI and GAP/IPDI (where GAP, HMDI, TDI and IPDI are glycidyl azide polymer, hexamethylene diisocyanate, toluene diisocynate and isophorone diisocyanate)systems in the presence of dibutyltin dilaurates (T12)was studied by variable temperature FTIR spectrum method. Results show that the reactions of GAP and three kinds of isocyanates (HMDI, TDI and IPDI) are of the second order. Their reaction rates rise with increasing the reaction temperature. The values of activation energy for reactions of the GAP/HMDI, GAP/TDI and GAP/IPDI systems are 15.49, 12.27, 22.46 J·mol^-1, respectively, revealing that the reaction activity of three systems decreases in the order of GAP-TDI>GAP-HMDI>GAP-IPDI.

Abstract:Carbon is the main component of a combustion products of boron. It has important influence to secondary ignition combustion.The influence of different contents of carbon on the ignition and combustion characteristics of boron particles was studied by thermogravimetry(TG) and differential scanning calorimetry(DSC), X-ray diffractometer(XRD) and laser ignition test system. The mass contents of carbon in the mixture of boron and carbon samples were set to be 0%, 10%, 20%, 50% and 100%. Results indicate that the addition of carbon make the sample weight gain lower during the process of heating. The influence of the mass content of carbon on the heating process is complex. When the content of carbon is low, the oxidation reaction delays and the heat release increases, while as it increases, the results turn to be opposite. Under oxygen atmosphere, with an increase in the mass content of carbon, the maximum combustion peak intensity of the sample decreases, the burning time of the sample is prolonged from 2436 ms to 2909 ms, but the ignition delay of carbon to the sample is less, not more than 3 ms.The combustion products are black massive solid, which mainly consist of boron oxide and carbon, etc.The analysis of the combustion products of the sample shows that the ignition combustion reaction of the sample is not sufficient.

Abstract:To investigate the key factors which influence the erosion of propellants and the relationship between erosion and each factor, eight triple base gun propellants were produced. The amounts of erosion were determined with semi-closed bomb experiment. The relationship was found between the erosion of propellants and these factors, through contrasting and analysing explosion heat, explosion temperature and gases composition of these propellants respectively. Results show that explosion temperature is the key factor influencing the erosion of propellant, and there is a linear relation between erosion rate and explosion temperature(3100~3700 K), which increases obviously with the rise of explosion temperature. Explosion heat has not obvious influence on erosion, but erosion time or pressure impulse palys a more important role. H₂O is the most influential constituent to propellant erosion coefficient in five propellant combustion products, and the relationship between these products and propellant erosion is complex, now it is difficult to have a quantitative description separately.

Abstract:To satisfy the requirements of passive pressurized water reactor nuclear power station explosion valve for high-temperature-resistant gas-producing powder, the carbon black/potassium nitrate (CPN) propellant was developed, and its performances were tested and evaluated by DSC, TGA, closed bomb test, linear burning rate test, friction sensitivity and electrostatic sensitivity tests. The comparison of performances of CPN and black powder (HY6) and sulfur-free black powder (WHY6) was carried out. Results show that the auto ignition temperature of the CPN propellant is over 321 ℃, revealing that the CPN propellant has good thermal stability and high temperature-resistance ability. The CPN propellant has the ability of producing gas to do work. The burning rates increases in the order; CPN < WHY6 < HY6.The values of friction sensitivity and electrostatic sensitivity of the CPN propellant are 0. The safety of the CPN propellant is better than that of HY6 and WHY6.

Abstract:In order to reduce the size of adapter, ensure the output synchronization of detonation wave and increase the connection strength between adapter and detonation fuses, a new way of splitting detonation fuses was put forward, and a small adapter with Φ5 mm×6 mm was designed.The prototypes of "one input two output" and "one input four output" flexible linear explosive circuit were manufactured, tested and analyzed. The results show that this small adapter can work reliably, and the output deviation of "one input two output" and "one input four output" flexible linear explosive circuit are less than 34 ns and 73 ns, respectively. Moreover, the interface between booster charge and detonation fuse in the adapter is found to affect the output synchronization of detonation wave.

Abstract:To improve the anti-overloading ability of initiating explosive device under ammunition penetration target, polytetrafluoroethylene (PTFE) materials with varied thickness were added at the bottom or the outer wall of detonators to weaken the impact stress wave and the strength of inertial overload. The standard one-leg bridge-wire electric detonators were used as strengthening object. The mechanism and effectiveness of this reinforcement method were studied by gas gun experiment and numerical simulation. Experiment and the simulation results show that the buffer layer isolates the impact stress wave and cushions the mass inertia of the detonators. With the increase of gasket thickness, the overload acceleration and overload damage of detonator decrease gradually. When the buffer layer thickness is greater than 0.9 mm, the detonator has no obvious damage. The addition of PTFE materials on the detonator has an obvious protective function.

Abstract:To optimize the performance of exploding foil initiators, the velocity histories of mini flyers driven by electrically exploded foils were obtained by Photonic Doppler Velocimetry (PDV). A electrically driven flyer device was designed, which could generate a mini flyer with Φ0.35 mm×25 μm size and the flyers in tests do not have any special treatment. Two shot flyers were tested by PDV diagnostics, and the velocity histories of mini flyer were obtained. The effective length is about 160 ns. The maximum velocities of two shots of flyers are 4520, 4330 m·s^-1 respectively, and the velocity difference is about 4%, which having a good consistency. The profiles of two velocities have an evident inflection point. Before the point, the velocities grow quickly and reach 75% of the final velocity in 60 ns (0.01 mm displacement). After the point, the velocities grow relatively slow and finish the rest 25% acceleration in 100 ns.

Abstract:According to the requirement of moisture content (1%-3%) and detection precision(0.1%) for the flat gunpowder, the capacitive sensor of varied dielectric was adopted, and the system of capacitive sensor for the moisture detection of gunpowder was developed. On the basis of the analysis for temperature, moisture, mass and voltage amplitude, the multi-linear regression model of partial least-squares was established. Results show that the maximal measurement error of moisture content (0.3%-1%) is 0.12%, and the maximal error of moisture content(1%-3%) is less than 0.087%, which meeting the accuracy requirement for the moisture detection (0.1%) of gunpowder.

Abstract:Polynitrogen compounds (containing only nitrogen atoms) are promising candidates as High Energy Density Material(HEDM) for propellants and explosives. Polymeric nitrogen particularly for cubic-gauche nitrogen (cg-N) has the highest energy contents in polynitrogen compounds. From theoretical estimates, cg-N can provide a specific impulse of 500 sec with material density 3.9 g·cm^-3, which is a tenfold improvement in detonation pressure over HMX. cg-N was produced experimentally in 2004 by compression of molecular nitrogen in adiamond anvil up to a pressure of 140 GPa at a cell temperature higher than 2000 K, but it cann′t be restained at ambient condition If polymeric nitrogen can be obtained at ambient condition, this will be a milestone in the development of energetic materials. Therefore a brief review of cubic-gauche nitrogen (cg-N) and previous amorphous (semiconducting) polymeric nitrogen were overviewed in this paper. The properties of N₂/H₂ alloy, which was prepared with N₂/H₂ (volume ratio 2:1) mixture under 85 GPa at room temperature, were also introduced.

Abstract:3, 6-Dihydrazine-1, 2, 4, 5-tetrazine and decahydrodecaboric acid were synthesized from the starting material 3, 6-di(3, 5-dimethyl pyrazole)-1, 2, 4, 5-tetrazine and [N(C₂H₅)₄]₂B₁₀H₁₀, respectively. Dihydrazine-1, 2, 4, 5-tetrazine decahydrodecaborate was obtained by neutralization reaction with the yield of 80%. The compound was characterized by IR, ¹H NMR, and elemental analysis. Moreover, the combustion heat of the compound determined by oxygen bomb combusion is 37.5 kJ·g^-1.

Abstract:The centimeter-level TNT single crystal was prepared using a solvent evaporation method. Its crystal structure was characterized by XRD and DSC. Results show that the crystal is monoclinic, the biggest crystal face is the (100) plane. The average indentation modulus and hardness of the (100) plane obtained at different indentation load by a nanoindenter are (17.40±0.35) GPa, (0.81±0. 05) GPa, respectively, which is significantly higher than the compression modulus of TNT casting explosive.

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