Abstract:The distribution of initial fragment velocity in the aim direction is one of the important factors for evaluating the power of the directional warhead. Therefore， the calculation method of the initial fragment velocity in the whole domain on the directional side of the warhead under the eccentric double-line initiation and the kinetic energy gain compared with the central initiation are studied. Based on the infinitesimal theory， the calculation method of the initial fragment velocity in different circumferential position on the directional side was derived， and the static explosive experiment of the warhead was carried out to compare with the theoretical result. Combined with the numerical result of the warhead， the axial velocity correction function was fitted， and the universality of the algorithm was verified according to the existing research. It is shown that the proposed formula is suitable for the warhead with eccentric double-line initiation， and the error between theoretical calculation and test results is within 4.80%， calculation result is consistent with actual situation. The fitting correction function can predict the initial velocity of the fragments in different axial direction. The algorithm still has good universality when the warhead parameters change and the calculation error is less than 7.11%. Compared with central initiation， the eccentric double-line initiation mode with an angle of 60° can increase the total kinetic energy of the fragments in the range of -30°-30° from the center of the directional side by 34.9%.

Abstract:In order to break through the current limitation of simulation accuracy for the ultrasonic detection of TATB based PBX and to realize the structure-performance relationship based nondestructive ultrasonic testing and characterization， an ultrasonic simulation method based on CT image modeling （MBCT） was proposed. Using the significant difference of gray-level distribution between the particle phase and the binder phase in CT images， the structural morphology and features of the sample were extracted. A two-dimensional geometric structure model containing molding powder particles and boundary morphology was obtained by processing the CT slice image with noise reduction， binarization and boundary optimization. Then， the model was used for finite element simulation of ultrasonic propagation， and the differences between MBCT and conventional Voronoi model were quantitatively compared. Results show that the MBCT can effectively and precisely describe the random complex structure characteristics of TATB particles and boundary morphology， which makes the ultrasonic simulation results have better consistency with the experiment ones. The errors of sound velocity， attenuation， frequency domain amplitude and apparent integrated backscattering （AIB） coefficient were 0.32%， 1.14%， 0.92% and 1.55%， respectively （within 2%）. Compared with Voronoi model（2.77%， 35.93%， 20.70%， 13.68%）， the error is greatly reduced， and the simulation accuracy is significantly improved.

Abstract:In order to describe the characteristics of the crystal morphologies of hexogen （RDX）， octogen （HMX）， and hexanitrostilbene （HNS）， the unified kinetic three-dimensional partitioning method was used to simulate the real-time growth morphologies of these three energetic material crystals. The influence of crystal growth conditions on crystal morphology and the topology of crystal face were studied. The research results show that the predicted crystal shape of RDX is rhombus-like， with the main crystal faces being （0 1 0）， （1 0 0）， and （1 1 0）. The crystal morphology of HMX exhibits a columnar shape， with the main crystal faces including （0 1 1）， （0 1 0）， and （1 1 -1）. The crystal morphology of HNS has a flake-like shape， with the （1 0 0） face having the largest exposed area. The predicted crystal morphologies of energetic materials are consistent with experimental results. When RDX， HMX， and HNS crystals exhibit 2D nucleation and growth modes， a higher driving force （Δμ=418.59 kJ·mol^-1） causes the molecular layers of the crystal to continuously stack， resulting in layered growth. When the temperature is low， growth units first attach to the crystal faces in the platform area， gradually forming "island-like" agglomerations， followed by epitaxial growth. When the crystal face is sufficiently large， multiple "island-like" structures of different sizes may appear， gradually merging over time. At lower driving force （Δμ=27.21 kJ·mol^-1）， HNS crystals exhibit spiral dislocation growth， where the （1 0 0） crystal face triggers lamellar growth through a spiral axis， resulting in "terraced" crystal face. Adsorption ability analysis reveals that the kink sites and step surfaces of the helix have strong adsorption ability， while the sites on the face have weak adsorption ability.

Abstract:Isowurtzitane derivatives are currently one of the most potential cage energetic compounds.In order to systematically study the high temperature thermal decomposition law of isowoodsane derivatives and clarify their detonation mechanism， in this work， the thermal decomposition properties of hexanitrohexaazaisowurtzitane （ε-CL-20）， 4，10-dinitro-2，6，8，12-tetraoxa-4，10-diaztetracyclododecane （TEX） and 4，10-diazomethyl-2，6，8，12-tetranitrohexaazaisowurzane （BATNIW） under high temperature（1500-3500 K） were studied by molecular dynamic simulations with ReaxFF-lg reactive force field and molecular dynamics method. The results show that the denitro and ring opening are the main initial reactions of ε-CL-20， TEX and BATNIW， in which the ring opening mainly occurs at the C─N bonds or C─O bonds of the five membered rings. Among the decomposition products， the yields of CO₂ and H₂ change significantly under different temperature， while content of N₂ are similar at temperature higher than 3000 K. The decomposition of BATNIW produced N₂ with the highest reaction rate and the maximum yield. During the thermal decomposition of TEX， clusters could easily be produced， and glyoxal could be regarded as its characteristic product. The order of thermal decomposition activation energy of the three derivatives is TEX > BATNIW > ε-CL-20， which suggests TEX shows the best stability. This work preliminarily reveals the relationship between the molecular structure and thermal decomposition of three isowurtzitane derivatives.

Abstract:In order to explore the influence of the radial air gap in the hole on the directional penetration effect of shaped charge with/without metal liner and the detonation energy transfer process of explosive， ANSYS/LS-DYNA software was used to carry out the numerical simulation study when the air gap of the charge in the hole was 6， 8， 10， 12， 14 cm. The process of centralized release of energy from the shaped charge with metal liner forming an EFP and without metal liner forming concentrated detonation product flow as well as the depth of directional penetration into the borehole wall， was analyzed. The results show that when the air gap is less than 10 cm， the penetration depth of concentrated detonation product flow into the hole wall is increased by 53% （6 cm） and 29% （8 cm）， respectively， compared with the average penetration depth of EFP. When the air gap was greater than 10 cm， the average penetration depth of EFP increased by 26% （12 cm and 14 cm） compared with the concentrated detonation product flow. The kinetic energy of EFP and concentrated detonation product flow per unit area through the hole wall on the shaped energy axis was calculated， it is found that when the air gap is small， the energy dissipation of concentrated detonation product flow in the air is less than that of EFP plastic deformation， and the penetration effect of concentrated detonation product flow on the hole wall is better. When the air gap is large， the density and kinetic energy at the axis of the concentrated detonation product flow are significantly reduced due to the spatial expansion of detonation products， while the EFP has high density and incompressibility， small energy dispersion and slow decay of kinetic energy， so the penetration effect of EFP on the hole wall is better than that of the concentrated detonation product flow.

Abstract:The velocity of the flyer is a key factor in determining the reliability of initiating exploding detonators. In order to investigate the influence of barrel parameters on the flyer velocity， the factors affecting the flyer velocity were analyzed through both experimental and numerical simulation methods. A TiW/Ni/Au composite film exploding foil with a film thickness of 0.5/0.5/2 μm and dimensions of 0.15 mm×0.15 mm was designed and prepared using magnetron sputtering technology. Under excitation conditions of 0.1 μF and 1200 V， a polyimide flyer with a density of 1.45 g·cm^-3 and a thickness of 25 μm was selected， and the flyer velocities with different barrel parameters were measured using photon Doppler velocity testing technology. The research results indicate that， under the same diameter conditions， the flyer velocity initially increases and then decreases with increasing barrel thickness， reaching a peak at 0.4 mm. When the barrel diameter are 0.15， 0.23， 0.3， 0.35， 0.45 mm， the flyer velocity decreases as the diameter increases， with the highest velocity observed at a diameter of 0.15 mm. Furthermore， under the same thickness and diameter conditions， the velocities obtained from polyimide and ceramic barrel tests exhibit similar trends and values， with polyimide demonstrating higher strength and toughness and lower cost， making it a viable alternative to ceramic as a barrel material. Furthermore， a numerical simulation method was used to re-fit the empirical formula for flyer velocity applicable to the TiW/Ni/Au composite thin film， and the verification results show that the deviation between the calculated results and experimental data is within 2.5%.

Abstract:Traditional methods are difficult for the purification of TATB due to its poor solubility. Green deep eutectic solvent （CS-1） displays good solubility toward TATB， so CS-1 was used as the solvent with water as back extractant to develop a new purification method for TATB in this study. The difference between this method and other methods were investigated for the purification of TATB. Purification conditions including the amount of back extractant， washing times and drying methods were comprehensively optimized to improve the purity of TATB. Finally， a new method has been established for highly efficient separation and green purification of TATB. Through this method， high-purity TATB was obtained with the purity of （99.7±0.2）% and good recovery of 92.5%. Further， spectroscopic monitoring was combined with theoretical simulation to study the kinetics of the purification of TATB， and then a purification mechanism has been proposed， which is based on the dissociation of TATB’s complexes through the competition of hydrogen bonding between CS-1 and water.

Abstract:Ammonium dinitramide （ADN）， as a highly promising new oxidant， is still difficult to achieve large-scale applications due to its strong hygroscopicity. Numerous studies show that the strong hygroscopicity of ADN is mainly attributed to the formation of hydrogen bonds between NH₄⁺ cations and water molecules in air. In this work， a novel dinitramide energetic ionic salt （DBDN） containing divalent cation was synthesized by a simple， safe and efficient one-pot reaction using terephthalaldehyde （TPA）， aminoguanidine hydrochloride （AGC） and ADN as raw materials through Schiff base reaction and ion exchange reaction. The product was characterized by elemental analysis， infrared spectroscopy， and nuclear magnetic spectroscopy. Its physical and chemical properties were tested by thermal analysis， mechanical sensitivity testing， and theoretical calculations. In addition， the hygroscopicity of ADN and DBDN was studied by using the desiccator equilibrium method. The impact sensitivity （IS）， friction sensitivity （FS） and thermal decomposition temperature （T_d） of DBDN are >40 J， 16% and 225 ℃， respectively. The stability of DBDN is much better than that of ADN （5 J， 76% and 198 ℃）. Under the conditions of 25 ℃ and relative humidity （RH） of 66% and 75%， after 9 days， the hygroscopic rates of the ADN are as high as 24.1% and 39.5%， respectively， while those of DBDN are only 0.26% and 0.48%， showing non-hygroscopic properties of DBDN.

Abstract:Branched glycidyl azide polymer （BGAP） has higher relative molecular mass， wider adjustment range of hydroxyl functionality （f）， higher heat of formation and lower viscosity than linear glycidyl azide polymer （GAP）. It can increase the energy level， and improve the processing and mechanical properties of the composite solid propellant. Therefore it has become a hot research topic in the field of the azido polyether binder. However， the essentially important key to obtain high quality BGAP energetic binder is how to control and regulate some structural parameters such as hydroxyl functionality， molecular weight and molecular weight distribution. This paper illustrates two synthetic methods and processes of BGAP， proposes the possible reaction mechanism， and summarizes the progress in performance research. Some problems and deficiencies are pointed out. Finally， the development prospects of BGAP in the field of synthesis and performance research are forecasted. It is concluded that optimizing the extraction procedure after reaction， improving the throughput per run， and strengthening the studies in fundamental performance and application will be the focuses in future researches.

Abstract:Gunshot residue （GSR） is an important concomitant product of gun firing， and the analysis of GSR is of great significance in the investigation and litigation of gun-related cases. The traditional GSR test mainly focuses on the inorganic substances produced by primer， but neglects the organic gunshot residue （OGSR） from the propellant. Due to the widespread presence of metal particles in the environment and the production and application of non-heavy metal ammunition， conventional detection methods are prone to false positive or false negative problems. The trace detection technology of OGSR is becoming a research hotspot. The research progress of trace OGSR detection in recent years was reviewed. The advantages and limitations of Raman spectroscopy， mass spectrometry， liquid chromatography-mass spectrometry and electrochemical method in OGSR detection were discussed. The application of chemometrics in trace OGSR detection was introduced. Among them， liquid chromatography-mass spectrometry （LC-MS） is a simple pre-treatment method for OGSR detection with low detection limit and high sensitivity. In the future， the focus of research is to combine the large amount of data obtained based on liquid chromatography-mass spectrometry with the data processing technology of chemometrics to build a detection technology with rapid analysis and identification of OGSR samples.