Abstract:

Abstract:To investigate the influence of cylindrical charge geometry on blast load distribution under internal explosion conditions， 16 numerical models were developed using LS-DYNA following experimental validation. A comprehensive parametric study was conducted to systematically evaluate the effects of three key factors： charge length-to-diameter ratio （L/D=1-5）， ignition location （head， center， tail）， and charge orientation. The analysis compared overpressure contours， reflected overpressure-time histories， impulse-time histories， and peak values across different scenarios. The results indicate that the L/D ratio exhibits the most significant impact on blast load distribution. As L/D increases from 1 to 5， the reflected overpressure ratio decreases dramatically from 37.5%-1287.9% to 25.5%-356.7%， and the reflected impulse ratio reduces from 88.7%-235.3% to 76.5%-132.8%. The effect of ignition position is region-specific， with the maximum differences in reflected overpressure and impulse ratios reaching 2173.3% and 328.0%. Charge orientation influence diminishes with increasing L/D ratio and incidence angle. Specifically， when L/D ratio increase from 1 to 5， the maximum reflected overpressure ratio decreases from 1287.9% to 356.8%， and impulse ratio decreases from 235.3% to 132.7%. The distribution of internal blast loads is primarily governed by the L/D ratio， followed by charge orientation and ignition location.

Abstract:To investigate the deformation behavior of explosive powder during bidirectional compression， as well as the pressure and density distribution laws of the explosive column， a random packing model considering the molding powder size distribution of the powder was established using ANSYS APDL parametric design language. Based on the finite element method of continuum mechanics， the dynamic bidirectional compression process of the powder was simulated and calculated. The results show that the model exhibits a good simulation effect on the bidirectional compression process of the powder， with the maximum error between the experimental and simulation results under various specific pressures being only 2.044%. The relative density of bidirectional compression is higher than that of unidirectional compression， and the improvement in the low-pressure region is more significant. The axial pressure and density distribution of the explosive column are characterized by being larger at both ends and smaller in the middle， while the radial distribution shows smaller values on both sides and larger in the middle. Since the radial pressure difference is ≤6 MPa， while 66% of the axial pressure differences exceed 6 MPa （with a maximum of 26.8 MPa）， the radial density distribution can generally be neglected. During compression， the powder mainly undergoes deformation along the axial direction， with molding powder rotating and transforming from regular to irregular shapes. The parts in contact with the punches and mold are flat， and there are basically no gaps between molding powder.

Abstract:Based on the high calorific value of the Ti/B binary system， this study designed and fabricated the Ti/B/PTFE reactive materials with high energy release efficiency. The materials exhibited practical application prospects in the industrial field. To investigate the energy release characteristics of the Ti/B/PTFE reactive materials， the study conducted combustion tests， dynamic mechanical property experiments and ballistic gun experiments. By employing the oxygen bomb calorimeter and the Split Hopkinson Pressure Bar （SHPB） apparatus， the combustion and dynamic mechanical properties of the Ti/B/PTFE reactive materials were obtained. The influences of PTFE content and ambient atmosphere on the energy release characteristics of Ti/B/PTFE reactive materials were analyzed through the confined vessel impact energy release experiments. The study further calculated the energy release efficiency of the Ti/B/PTFE reactive materials under different operating conditions based on the closed tank pressure curves. Results indicate the energy density of 63.3%Ti/26.7%B/10%PTFE reactive materials（26.15 kJ·g^-1） and 60.6%Ti/24.4%B/15%PTFE reactive materials（26.47 kJ·g^-1） is high than traditional reactive material Al/PTFE（13.89 kJ·g^-1）. Ti/B/PTFE reactive materials exhibit strain rate effect. With the increase of strain rate， the yield strength of the 10% PTFE specimen increases from 28.3 MPa to 34.2 MPa and that of the 15% PTFE specimen increases from 47.1 MPa to 51.1 MPa. The impact energy release process of Ti/B/PTFE reactive materials in confined vessel can be divided into four stages： material destruction， hot spot formation， combustion energy release and pressure relief. The reaction efficiency of Ti/B/PTFE reactive materials depends on the impact velocity. As the impact velocity increases， the reaction efficiency improves significantly. Compared with the inert atmosphere， the energy release of Ti/B/PTFE reactive materials is more intense in air. This is attributed to the oxidation reaction between reactive elements and oxygen in the air.

Abstract:When multi-point explosions occur within a cylindrical shell containment， the generated multiple shock waves experience superposition and coupling， interact with the vessel walls to produce reflected waves， and ultimately resulting in a highly complex internal flow field. To investigate the flow field characteristics and the key influencing factors for multi-point explosions within a cylindrical shell， a two-dimensional plane-strain ring model was employed and studied. The results demonstrate that the evolution of the flow field exhibits periodic behavior. Specifically， when there are 2 explosion points， the reflected wave pressure at the observation points near the inner wall of the circular ring is significantly increased compared with that of the central single-point explosion. Especially when the distance from the explosion points to the center of the ring is 0.6 times the radius of the circular ring， this pressure value can reach up to 4.58 times that of the central single-point explosion. Shock wave coupling in configurations with two or three explosion points enhances structural deformation of the circular shell. However， as the number of explosion points increases further， the radial displacement of the shell gradually diminishes. Under conditions where the total explosive mass remains constant and the radial distance of the explosion points from the center is constrained between 0.2 and 0.8 times the shell radius， the two-point configuration induces the most significant structural deformation.

Abstract:To establish accurate and efficient quality control standards for the purity of 1，3，5-trichloro-2，4，6-trinitrobenzene （TCTNB）， the comprehensive performance of the classical acid-base titration method and a newly developed green liquid chromatography method was systematically compared. The acid-base titration method quantifies TCTNB by hydrolyzing it with sodium hydroxide followed by back-titration of the excess base. The liquid chromatography method innovatively employed low-toxicity methanol instead of traditional toxic solvents and achieved baseline separation of the target compound from impurities on a C18 column. Experimental results indicated that the titration method was cumbersome （requiring 5.9 hours per analysis） and exhibited significant inaccuracy， showing a mean measured value of 93.89% with a substantial systematic negative bias of -6.05% compared to the sample''s nominal value. In contrast， the liquid chromatography method demonstrated higher efficiency （requiring 3.2 hours per analysis）， good precision （with a relative standard deviation <0.30%， n=6）， and excellent accuracy， showing a mean value of 99.82% that closely matched the nominal value of 99.94%. The substantial systematic error in the titration method was primarily attributed to the deep color of the hydrolyzed solution， which introduced subjectivity in endpoint determination， and potentially incomplete hydrolysis or interfering side reactions. The liquid chromatography method effectively overcame these limitations due to its superior separation selectivity and detection stability. The newly established liquid chromatography method significantly outperforms the traditional titration method in terms of accuracy， precision， efficiency， and green safety.

Abstract:In this study， to gain deeper insight into the combustion characteristics of single-base propellant， a multi-parameter measurement system based on laser diffuse reflection spectroscopy was developed. This system was employed to measure the combustion parameters of both single-base and double-base propellants. As a result， the combustion spectra and burning rates of both propellant types were successfully obtained. The experimental results revealed that within the 250-500 nm wavelengh range， emission peaks of OH*（313.9 nm）， CO₂*（462.3 nm）， and CHO*（421.7 nm） were observed， attributed to the active intermediates generated during single-base propellant combustion. Meanwhile， in the 500-780 nm range， distinct emission peaks of Na*（588.7 nm）， K*（766.8 nm）， and Ca*（554.6 nm） were detected， analyzed to originate from residual lignin in nitrocellulose. Compared with the burning velocity measurement results from the image and target line methods， the laser diffuse reflection spectroscopy method showed consistent results， with maximum relative errors of 4.17% and 9.97%. Furthermore， the results from double-base propellant combustion parameter measurements indicated that this method is also applicable for the simultaneous measurement of combustion velocity and spectra of double-base propellants. The developed method possesses feasibility and versatility， enabling non-contact and non-destructive measurement of propellant burning velocity.

Abstract:Carotenoids， valued for their exceptional free radical scavenging properties and low biological toxicity， were systematically investigated as potential stabilizers for propellants. A comprehensive evaluation strategy， incorporating differential thermal analysis （DTA）， methyl violet test strips， isothermal thermogravimetry， vacuum stability testing， and accelerating rate calorimetry （ARC）， was employed to assess their stabilizing effects. Four representative carotenoids-lycopene， β-carotene， xanthophyll， and astaxanthin， were examined for their stabilization performance in nitrocellulose （NC） and absorptive composition systems. All tested carotenoids demonstrated superior thermal stability compared to conventional stabilizers. Notably， astaxanthin exhibited the most significant enhancement： it prolonged the methyl violet discoloration time of NC by 40 min， reducing mass loss by 17.90%， decreased the maximum adiabatic decomposition temperature rise rate by 0.134 ℃·min^-1， and lowered gas pressure release per unit mass by 12.0 kPa. In absorptive compositions， it extended the methyl violet discoloration time by 34 min while reducing mass loss by 14.18%. Free radical scavenging tests and intermediate structural analyses revealed the underlying stabilization mechanism： carotenoids effectively suppress autocatalytic decomposition via nitrogen-oxygen free radical capture， achieving nearly 90% scavenging efficiency at 8 mmol·L^-1. Additionally， secondary derivatives formed during carotenoid degradation were free of nitrosamine groups， significantly reducing toxicological concerns.

Abstract:To enable comprehensive prediction of typical fuze cook-off processes and address the challenge of quantifying output pressure， an advanced strain-gage pressure bar sensor was utilized for dynamic pressure acquisition during experimental investigations. A comprehensive coupled numerical framework was developed， integrating heat transfer models， Arrhenius reaction kinetics， and ignition response mechanisms， to systematically analyze the cook-off behavior and generate detailed pressure profiles of booster explosives. The kinetic parameters， such as activation energy and pre-exponential factors， were inversely determined through the application of a Back Propagation （BP） neural network. Meanwhile， the state parameters that govern the ignition reaction equation were optimized using a multi-island genetic algorithm. Coupled simulations utilizing ANSYS Fluent and LS-DYNA within the Workbench platform were performed to numerically investigate the cook-off response under different heating rates. This approach enables comprehensive full-process characterization from thermal reaction to ignition. The results indicate that slower heating rates shift the ignition zone toward the central region of the charge， thereby intensifying the severity of the reaction.

Abstract:This paper reviews the research and application progress of four types of on-site rapid detection methods for explosives （chromatography-mass spectrometry coupling， spectroscopic analysis， ion mobility spectrometry， and chemical sensing）， analyzes and summarizes their suitable targets， advantages， and limitations， and provides an outlook on their development directions. Among chromatography-mass spectrometry coupling technologies， gas chromatography-mass spectrometry （GC-MS） offers high sensitivity and are suitable for volatile and thermally stable explosives. Liquid chromatography-mass spectrometry （LC-MS） requires stringent operating conditions but are suitable for most inorganic and organic explosives. Among spectroscopic techniques， Raman spectroscopy requires only a small sample amount and are simple to operate， but it poses explosion risks for highly sensitive explosives. Terahertz spectroscopy （THz） is safer and has strong penetration， but it is easily influenced by environmental factors and is suitable for explosives with characteristic absorption peaks. Ion mobility spectrometry （IMS） provides low detection limit and rapid response， but they are difficult to balance resolution and sensitivity， making it more appropriate for volatile explosives. Among chemical sensing technologies， fluorescence probe methods show high sensitivity， good selectivity， and visualization capabilities， but they are susceptible to interference and relatively complex to operate. Chemical colorimetric methods are simple， inexpensive， and fast-responding but are easily interfered with and mostly limited to the visible light. Both methods are only suitable for specific explosives. By analyzing and comparing existing technologies， it is proposed that future research should focus on the integration of multiple technologies， device miniaturization， enhancement of anti-interference capability， and optimization of multi-target detection capabilities， in order to improve the anti-interference performance， on-site rapid detection of multiple targets， and intelligence level of detection methods， providing a reference for perfecting on-site explosive detection technology and ensuring the effective implementation of safety and security measures.