In order to study the ignition and explosion properties of micro-nano self-assembled and physically mixed aluminum powder materials, the ignition sensitivity, flame propagation characteristics and explosion parameters of the materials were studied through a 1.2L Hartmann tube and a 20L ball explosion test system. The results show that compared with Al-T4 micron aluminum powder, nano-aluminum powder can significantly reduce the ignition energy of aluminum powder materials.And the ignition sensitivity of the self-assembly process is further increased compared with that of aluminum powder materials with physical mixed process. In terms of the flame propagation speed, the high reaction rate of a small amount of nano-aluminum powder can accelerate the reaction of micron aluminum powder, and the self-assembled aluminum powder is easy to ignite and the heat transfer is more efficient due to the overall synergistic effect of micro-nano aluminum powder. In the 20L ball explosion test system, the maximum explosion pressure and explosion index of self-assembled and physical mixed aluminum powder with 5% mass fraction of nano content are 0.72MPa, 0.75MPa, 43.21MPa·m/s and 31.49MPa·m/s at 500g/m³. The maximum explosion pressure and explosion index of self-assembled and physical mixed aluminum powder with 10% mass fraction are 0.84 and 0.68MPa at 1000g/m³. The explosion pressure and explosion index of 5% mass fraction of nano aluminum powder increase first and then decrease with increasing the concentration, and the explosion pressure and explosion index of aluminum powder with 10% mass fraction increase with the increase of concentration. The explosion power of the composite system isnot only related to the activity, but also has a certain relationship with the calorific value of the powder.

To investigate the enhancement effects of free hydrogen produced by metal hydrides on the damage performance of fuel air explosive(FAE), A 20L spherical liquid explosion test system and the colorimetric temperature measurement technology were used to study the effects of different matrix liquid fuels and metal additives on the shock wave and thermal damage performance of FAE. The results show that epoxypropane(PO)has the best explosion performances of the three liquid matrix fuels commonly used in FAE. When titanium hydride(TiH₂)powders are added to PO, the explosion overpressure, maximum pressure rise rate and maximum average temperature of the mixed fuels increase first and then decrease with the increase of TiH₂ powders content, reaching the maximum values when the mass fraction of TiH₂ powders was 35%, namely, 1.21MPa, 68.73MPa/s and 2398K, respectively. Compare to Ti-PO mixed fuels, the TiH₂-PO mixed fuels has more continuous combustion flame and more excellent explosion performances at the same mass concentration. The research results indicate that as a potential high-energy additives, TiH₂ could be effectively applied to FAE to improve its explosion characteristics and enhance the shock wave as well as the thermal damage performances.

The concave honeycomb structure has broad application prospects in the automotive industry,aerospace,biomedical and other fields due to their unique deformation mode,excellent impact resistance and energy absorption properties,and lightweight characteristics.Based on the traditional Concave hexagonal honeycomb structure,a deformation-controllable concave honeycomb structure based on rounded corners enhancement is proposed by introducing a rounded corner design and changing the arrangement of the rounded corners,and a deformation-controllable honeycomb structure with deformation modes of Z and Y shapes is designed and prepared using metal 3D printing technology.In order to explore its impact resistance,its deformation mode and energy absorption properties are analyzed through the quasi-static compression and drop weight impact experiments and the finite element numerical simulation.The research results show that the proposed honeycomb structure achieves controllable deformation mode and has higher crushing stability,and the energy absorption performance of the structure is significantly improved through customized Z and Y deformation modes.For the same structure,the energy absorption performance gradually improves as the fillet radius increases.As the speed increases,the structural deformation mode gradually evolves into an I type collapse,the platform force generally shows an increasing trend,and the energy absorption efficiency gradually decreases.Due to the asymmetric arrangement of the rounded corners,the Z shape structure has better impact resistance than the Y shape structure in most cases.The research results can provide reference for the crashworthiness design of new structures under dynamic impact.

In order to quantitatively analyze the effect of explosion impact on the ignition energy of electronic detonator,seven sets of impact experiments with different strengths are made for liquid aluminum electrolytic capacitors by underwater explosion method.The dielectric breakdown behavior and leakage current change rule of capacitor under impact load are studied,and the energy loss path of electronic detonator capacitor is analyzed.An impact-ignition model of electronic detonator is established.The functional relationship between shock wave overpressure and ignition energy is obtained.The results show that the dielectric breakdown of capacitor sample occurs under the shock wave overpressure of 8.5-40.6MPa,and the voltage drop increases exponentially with the increase in shock wave overpressure.When the shock wave overpressure is greater than a critical value,the capacitor cannot heal completely after dielectric breakdown,and the leakage current increases to the mA level with an average value of 1.62mA.The ignition energy of electronic detonator decreases gradually with the increase in shock wave intensity,and when the leakage current increases,the ignition energy drops sharply.

Metal halide perovskites have become a current research hotspot owing to their exceptional optoelectronic properties and significant potential application value. The elemental composition and crystal structure of perovskite material have crucial influence on its performance.To realize the preparation of novel perovskites,this paper focuses on the research of synthesizing cesium lead chloride perovskite (CsPbCl₃) under shock loading.In this study,CsPbCl₃ perovskite powder is synthesized by the shock loading of detonation-driven flyer plates under the conditions of 0.6-0.8 relative densities of powder and 14.2-27.9GPa shock pressures.The characterization results of X-ray diffraction (XRD),scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicate that the recovered products are CsPbCl₃ perovskite powders.Experimental results also demonstrate that the shock pressure and the relative density of precursor are two key factors to the synthesis of CsPbCl₃ perovskite powder.Based on the experimental conditions and analytical characterization results,a formation mechanism of CsPbCl₃ synthesis is discussed.It is confirmed that the proper shock pressure for high-purity CsPbCl₃ powder synthesis is from 14GPa to 17GPa.It is also suggested that the shock synthesis method is a feasible approach for preparing difficult-to-synthesize perovskite.

In order to obtain the slow cook-off response characteristics of HMX-based pressed aluminized explosives under different restraint modes and strengths, a scaled cook-off bomb with charge length-diameter ratio of 5:1 was designed based on a typical supersonic ground penetration warhead. The slow cook-off experiments of HMX-based aluminized explosives under unrestrained and different restrained strengths were carried out. The reaction violence of HMX-based pressed aluminized explosives under unconstrained conditions, and the variation of charge reaction violence with different shell thickness(4, 10, 16 and 20mm)and end cover thread length(10, 12 and 14mm)were obtained. The results show that under the condition of slow cook-off, the HMX-based aluminized explosive reaction includes three stages: gas generation, combustion at the end cap and flame extinguishment. The restraint strength of the slow cook-off bomb affects the ignition time and temperature of the charge, and then affects the increase of the internal reaction pressure of the bomb, and finally leads to different reaction violence. When the thread length(L)is 14mm, with the shell thickness(δ)from 4mm to 20mm, the reaction violence develops from deflagration to explosion and then weakens to combustion; when the shell wall thickness(δ)is 10mm, with the thread connection length(L)increases from 10mm to 14mm, the reaction violence changes from combustion to explosion. When the shell wall thickness(δ)is equal to the equivalent shell wall thickness(δ_e), the restraint strength of the slow cook-off bomb is more uniform, which is beneficial to the continuous growth of the reaction pressure, and finally leads to a more violentexplosion reaction of the slow cook-off bomb.

To deeply understand the impact initiation,impact ignition,detonation process,and detonation product states of energetic materials under extreme conditions, the decomposition reaction processes of α-, β-, γ-and ε-CL-20 crystals under shock loading were studied using self-consistent charge density functional-based tight-binding(SCC-DFTB)in combination with multiscale shock technique. The influence of water molecules on the decomposition of α-CL-20 was also studied because α-CL-20 generally exists in the form of hydrate. The results show that γ-CL-20 has the largest compression ratio among these four CL-20 crystals at the same shock velocity. When the shock velocity is 8 km/s, γ-CL-20 completely decomposes, while the other three crystals do not completely decompose until the shock velocity reaches 9km/s. Moreover, the addition of water molecules can significantly increase the activity of CL-20 molecules, and accelerate the decomposition of solid phase α-CL-20. In addition, the initial decomposition path of CL-20 under shock loading is not significantly affected by the crystal forms, but is mainly affected by the shock velocity. When the shock velocity is lower than 8km/s, the decomposition reaction is triggered by the dissociation of N—NO₂ bond. However, when the shock velocity is higher than 9 km/s, the N—NO₂ bond is inhibited by high pressure. The H in the C—H bond may preferentially form a five-membered ring with the adjacent NO₂, and further produces NO and OH.

To study the explosiveness of biomass fuels, TG-DTG thermogravimetric analysis was used to analyze the combustion performance and kinetic parameters of several common biomass fuels(straw, sawdust, peanut shells)and their mixtures. The microstructures of these fuels were analyzed using scanning electron microscopy(SEM). Additionally, an elemental analysis of the wood powder and peanut shell powder mixture was carried out using an elemental analyzer. Based on the elemental composition, the amount of oxygen required for its oxidation reaction was calculated, and an explosion test was subsequently conducted. The results showed that the mixed fuel(wood powder and peanut shell powder in a 1:1 mass ratio)exhibited high stable combustion characteristics, flammability index, and overall combustion performance. The activation energy was moderate, and the surface appeared porous and rough, with more free surfaces and a larger specific surface area, which facilitated combustion. In an experiment,40g of this mixed fuel was loaded into a steel pipe with a diameter of 40mm, a length of 200mm, and a wall thickness of 1.5mm, and filled with 5MPa oxygen. The mixture was successfully detonated by a No.8 electronic detonator without producing toxic gases. The steel pipe was blasted into fragments of different sizes, with most fragments measuring less than 50mm. The research results indicate that biomass fuel can exhibit explosiveness under certain conditions.

In order to research the explosion characteristics of HMX-based aluminized explosives with different charge structures in confined space, experiments on the confined explosion of samples with composite charge structures and uniform charge structures were carried out. A closed explosion experimental device with temperature and pressure measurement was established. The explosion pressure and temperature of the sample with composite charge structure were compared with the same sample having the uniform charge structure. The result shows that the peak pressure and quasi-static pressure of the explosion shock wave of the sample with composite charge structure are 12.7% and 8.0% higher than those with the uniform charge structure, respectively. The explosion energy release in confined space can be improved through the composite charge structure, which consists of the outer layer with high detonation velocity explosive and the inner layer with high aluminum/oxygen ratio explosive. The peak explosion temperature of composite charge structure is 621℃, which decreses by 124℃ compared with the uniform charge structure of 745℃, but the samples with composite charge structure can maintain a high temperature around 600℃ in confined space for a long period.

The effects of altitudes and the decoupled conditions of low pressure and temperature on the blast wave parameters of moving charge were investigated by employing the AUTODYN software. Additionally, a theoretical calculation model was developed to predict peak overpressure of the moving charge under low pressure and temperature. The model was validated subsequently through experimental data and numerical simulations. The results indicate that the model can assess the blast wave peak overpressure of moving charge at low temperature, pressure and coupled high-altitude environment effectively. The peak overpressure of the blast wave generated by the moving charge decreased by an average of 35.6%, the action range increased by 62.0% for altitude increased from 0 to 10000m. With the ambient temperature decreased, the peak overpressure of the blast wave increased by an average of 0.43%, the action range decreases by 11.9%; and with the ambient pressure decreased, the peak overpressure of the blast wave decreased by an average of 36.4%, the action range increased by 83.5%. The increase coefficient of blast wave overpressure resulting from the moving charge at various altitudes closely resembles that of low pressure. In high-altitude settings, the action range and overpressure of the blast wave from the moving charges explosion are predominantly influenced by pressure, whereas the effect of temperature is comparatively marginal.

To investigate the bubble pulsation and water jet characteristics under the gas-liquid-solid multiphase coupling effect of underwater explosions near the seabed, the Euler method was employed to establish a numerical model of underwater explosions near the seabed under different substrate/water depth conditions. The full physical process of underwater explosions near the seabed under muddy substrate conditions was simulated and compared with experimental results, which showed good agreement, verifying the effectiveness of the algorithm in solving the problem of underwater explosion bubbles near the seabed. Based on this, the influence of seabed substrate and water depth on the bubble morphology, radius, period, and water jet of underwater explosions near the seabed was discussed. The results show that under the premise that the bubbles can be split, the harder the substrate, the faster the bubbles split, and the deeper the water depth, the slower the bubbles split. The harder the substrate and the deeper the water depth, the smaller the maximum radius and period of the bubble, the larger the proportion of the bubble in the total bubble volume at the moment of splitting, and the smaller the peak velocity of the two water jets generated by splitting. During the evolution of the downward water jet, a reverse water jet will form. The harder the substrate, the greater the peak velocity of the reverse water jet. In all calculated cases, the depth parameter(H_ref)is in the range of 250—750, and the peak value of the reverse water jet velocity is positively correlated with the H_ref, and the H_ref is in the range of 750—1000, which is negatively correlated.

In order to investigate the energy release characteristics of the composite charge formed from Al/PTFE reactive materials and highly energetic explosive, three kinds of composite charge samples comprising Al/PTFE reactive materials with various components and mass ratios were prepared, and utilized to explosion tests. Free-field incident shock wave overpressure of several gauging points were measured. The process images of reactive materials scattering, reaction, and the fireball expansion were photographed. The reaction characteristics of reactive materials and the gain mechanism on the shock wave overpressure parameters were analyzed by comparing with the static explosion test of the bare charge. The results show that during the scattering process, reactive materials undergo self-reaction, anaerobic reaction with detonation products and aerobic reaction with ambient oxygen. Compared with bare charge, the secondary reaction enlarges the fireball and highly lengthens the duration of the flame, significantly enhances the shock wave simultaneously. At the gauging point of 2.5 meters, the maximum overpressure value and specific impulse are 1.8 times and 1.5 times of that the bare charge respectively, and the gain effect increases with the increase of aluminum contents in middle and far field range. However, the discrepancy narrows as the propagation distance increases due to the dilution of aluminum powders. By selecting the appropriate composition ratio and quality of Al/PTFE reactive materials, it is beneficial to compensate for the shock wave energy loss caused by the breaking and scattering of materials in the near field. Simultaneously, the after-burning reaction provides energy supplement for the middle and far fields, which is expected to achieve the overall gain of explosion energy release.

In order to improve the impact resistance and energy absorption of thin-walled circular tube,a carbon fiber reinforced composites (CFRP) thin-walled tube with porous array is designed to investigate its impact resistance and energy absorption performance under axial and transverse impact loads,respectively.A finite element model of CFRP thin-walled tube with porous arrays under impact loading is established based on the finite element method (FEM).The effects of different lay-up angles on the impact resistance and energy-absorbing properties of the structure are analyzed.Numerical results show that CFRP thin-walled circular tube with porous arrays has higher specific energy absorption and peak load,which are too high for the protected structure.But the peak impact load and specific energy absorption values can be changed by varying the lay-up angle of CFRP in order to enhance impact damage resistance.The maximum compression load within the effective compression displacement is reduced by about 10.1% and the specific energy absorption value is increased by about 15.1% when the lay-up angle of thin-walled circular tube with porous arrays is changed from [90°/45°/90°/0°]_2S to [90°/0°/90°/0°]_2S under axial impact loading.The preliminary results will be a guide for the engineering application of lightweighting and impact resistance enhancement of CFRP thin-walled tube.

Perovskite is regarded as one potential material for next-generation photovoltaic devices owing to its outstanding photoelectric characteristics which can be easily adjusted by phase transitions.However,the technology for intercepting and preparing the metastable perovskites is still in its infancy.The impact loading method has a significant advantage of high quenching rate,and enables the capture of metastable phases and facilitating their subsequent recovery and preparation.To achieve the impact phase transition treatment of CsPbBr₃,the cylindrical converging shockwaves are generated by the pulsed discharge of cylindrical wire array in water medium for studying the shock-induced phase transition of CsPbBr₃.The delicate control of shock pressure is applied to act on CsPbBr₃ powder by adjusting the charging voltage.After experiments,the samples are recovered and characterized.The characterized results reveale that the shock waves generated by pulsed discharge can induce phase transition in CsPbBr₃ powder under appropriate shock pressures (above 2 GPa).Additionally,the typical phenomena such as grain refinement,lattice distortion and nano-defects are observed in the recovered samples after shock-wave treatment.This study demonstrates that pulsed discharge of cylindrical wire array in water medium is a feasible converging shock wave loading technique,providing a novel approach to shock-induced phase transition loading.

The damage effects of ultra-high performance fiber reinforced concrete (UHPFRC) beams with different strengths subjected to blast loading are studied,with a focus on protecting typical architectural components from explosion.The influences of fiber content and longitudinal reinforcement type on the failure mode and dynamic response of UHPFRC beams are studied througth experiment.The results show that the increase in the fiber content and the use of high-strength steel (HSS) longitudinal reinforcement can improve the bending resistance of UHPFRC beams.A finite element model for UHPFRC beams under blast loading is developed to expand the research on damage effect.The parameters of the K&C constitutive model are calibrated using the single element test method,considering the factors like strength planes,equations of state,shear dilation,damage evolution,and strain rate effects.The quasi-static experiments demonstrate that the modified constitutive model parameters provide a more precise description of the mechanical characteristics of UHPFRC.Furthermore,the accuracy of the finite element model is also validated based on explosive experimental data.Finally,the influences of concrete strength,steel reinforcement type,and charge masses on the damage effects of UHPFRC beams at close range are further analyzed through parameter analysis.

In order to study the damage effect of the near-field strong shock wave on the covered charge,the dimensional analysis method on the sympathetic detonation with covered plate was established theoretically. The shock initiation process of covered-pressed TNT was numerically simulated by nonlinear finite element program ANSYS/LS-DYNA. The influence of covered plate thickness,donor charge mass,length-diameter ratio of donor charge on the detonation distance during non-contact explosion was analyzed. The functional relationship between covered-plate thickness and sympathetic detonation distance was obtained by a non-linear least square method,as well as the functional relationship between donor charge mass and sympathetic detonation distance. The results show that the dimensional analysis results are in good agreement with the fitting formula,which fully demonstrates the validity and accuracy of the fitting formula. The calculated detonation distance of the non-contact explosion decreases with the increase of the covered-plate thickness. While the covered-plate thickness is less than 3 mm,the increase of the covered-plate thickness has a greater impact on the sympathetic detonation distance. While the thickness is greater than 3 mm,further increasing the covered-plate thickness has significantly smaller effect on increasing the shock initiation resistance of explosive. When the length-diameter ratio of the donor charge remaining constant,the detonation distance of the non-contact explosion is linear with the donor-charge radius,and cubic with the donor-charge mass. Under the donor-charge mass remains constant,the detonation distance of the non-contact explosion is the largest when the diameters of the donor-charge and the acceptor charge are equal.

To investigate the bubble pulsation and water jet characteristics under the gas-liquid-solid multiphase coupling effect of underwater explosions near the seabed, the Euler method was employed to establish a numerical model of underwater explosions near the seabed under different substrate/water depth conditions. The full physical process of underwater explosions near the seabed under muddy substrate conditions was simulated and compared with experimental results, which showed good agreement, verifying the effectiveness of the algorithm in solving the problem of underwater explosion bubbles near the seabed. Based on this, the influence of seabed substrate and water depth on the bubble morphology, radius, period, and water jet of underwater explosions near the seabed was discussed. The results show that under the premise that the bubbles can be split, the harder the substrate, the faster the bubbles split, and the deeper the water depth, the slower the bubbles split. The harder the substrate and the deeper the water depth, the smaller the maximum radius and period of the bubble, the larger the proportion of the bubble in the total bubble volume at the moment of splitting, and the smaller the peak velocity of the two water jets generated by splitting. During the evolution of the downward water jet, a reverse water jet will form. The harder the substrate, the greater the peak velocity of the reverse water jet. In all calculated cases, the depth parameter(H_ref)is in the range of 250—750, and the peak value of the reverse water jet velocity is positively correlated with the H_ref, and the H_ref is in the range of 750—1000, which is negatively correlated.

To investigate the bubble pulsation and water jet characteristics under the gas-liquid-solid multiphase coupling effect of underwater explosions near the seabed, the Euler method was employed to establish a numerical model of underwater explosions near the seabed under different substrate/water depth conditions. The full physical process of underwater explosions near the seabed under muddy substrate conditions was simulated and compared with experimental results, which showed good agreement, verifying the effectiveness of the algorithm in solving the problem of underwater explosion bubbles near the seabed. Based on this, the influence of seabed substrate and water depth on the bubble morphology, radius, period, and water jet of underwater explosions near the seabed was discussed. The results show that under the premise that the bubbles can be split, the harder the substrate, the faster the bubbles split, and the deeper the water depth, the slower the bubbles split. The harder the substrate and the deeper the water depth, the smaller the maximum radius and period of the bubble, the larger the proportion of the bubble in the total bubble volume at the moment of splitting, and the smaller the peak velocity of the two water jets generated by splitting. During the evolution of the downward water jet, a reverse water jet will form. The harder the substrate, the greater the peak velocity of the reverse water jet. In all calculated cases, the depth parameter(H_ref)is in the range of 250—750, and the peak value of the reverse water jet velocity is positively correlated with the H_ref, and the H_ref is in the range of 750—1000, which is negatively correlated.

In the information warfare, the damage assessment of explosive fragments is of great significance to achieve accurate strike. However, the manual acquisition of distribution and geometric information of damage areas are inefficient in the damage experiment. To this end, a lightweight image segmentation model based on siamese networks and regional attention mechanisms is proposed, which achieves the efficient and accurate recognition of small-targeted spherical explosive fragmentation damage area under small samples. The model’s ability to perceive the explosion holes is improved by introducing the siamese structure, regional attention module and multi-scale convolution module. A loss function with multiple constraints is added and the best optimizer is screened so that the model optimization is more focused on the effective information for accelerating the model convergence. A quantitative detection method for the damaged area based on the connected-domain fusion watershed algorithm is proposed to achieve the accurate identification of the overlapping case of explosion broken holes. Experimental results show that the proposed method achieves higher efficiency and accuracy compared with the current mainstream models, and the average errors in predicting the area and diameter of damage region are 4.78% and 3.79%, respectively. The research work provides a reference for realizing the intelligent damage assessment of explosives containing fragments.

In order to study the thermal-mechanical coupling behaviors and mesoscale damage mechanism of HTPB solid propellants under high frequency cavitation impact, a three-dimensional full gradaed HTPB solid propellant mesoscale modeling was proposed considering the actual interface between particle and matrix. Different from the traditional meso-mechanical model in which virtual cohesive force interface element is embedded between particle/matrix interface, the thermo-mechanical coupling meso-mechanical model of solid propellant under the impact of cavitation microjet is further established. The breaking mechanism, damage mechanism, local stress strain and temperature distribution of solid propellant were analyzed. The results show that the AP particles break directly when the cavitating microjet acts on the AP particles. With the increase of impact degree, the interface layer between AP particles and HTPB matrix is fractured by impact. The maximum stress and strain values of solid propellant after cavitation microjet impact are 34.27MPa and 1.314, respectively. The stress wave transmission path change due to the obstruction of AP particles, Al particles, and interface phases. The maximum temperature value of the cavitation impact solid propellant process shows a gradually increasing trend due to the gradual accumulation of fracture energy, internal energy and friction energy. The maximum temperature value is 24.59℃. The solid propellant at a position far away from the cavitation microjet has no obvious temperature rise due to the low heat transfer coefficient.

To investigate the bubble pulsation and water jet characteristics under the gas-liquid-solid multiphase coupling effect of underwater explosions near the seabed, the Euler method was employed to establish a numerical model of underwater explosions near the seabed under different substrate/water depth conditions. The full physical process of underwater explosions near the seabed under muddy substrate conditions was simulated and compared with experimental results, which showed good agreement, verifying the effectiveness of the algorithm in solving the problem of underwater explosion bubbles near the seabed. Based on this, the influence of seabed substrate and water depth on the bubble morphology, radius, period, and water jet of underwater explosions near the seabed was discussed. The results show that under the premise that the bubbles can be split, the harder the substrate, the faster the bubbles split, and the deeper the water depth, the slower the bubbles split. The harder the substrate and the deeper the water depth, the smaller the maximum radius and period of the bubble, the larger the proportion of the bubble in the total bubble volume at the moment of splitting, and the smaller the peak velocity of the two water jets generated by splitting. During the evolution of the downward water jet, a reverse water jet will form. The harder the substrate, the greater the peak velocity of the reverse water jet. In all calculated cases, the depth parameter(H_ref)is in the range of 250—750, and the peak value of the reverse water jet velocity is positively correlated with the H_ref, and the H_ref is in the range of 750—1000, which is negatively correlated.

To study the deflagration to detonation transition(DDT)of 3,4-dinitrofurazanfuroxan(DNTF), DDT experiments under four ignition conditions were carried out by comparing DNTF and Composition B explosive. The propagation process of reaction wave front in DDT tube was measured, and the influence of ignition charge on detonation transition distance and detonation transition time of DNTF was analyzed. The results show that DNTF can be ignited when the ignition charge amount are 2.0, 1.0, 0.5 and 0.25g, and finally transformed into stable detonation. With decreasing the amount of ignition charge, there is no significant change in the detonation transition distance of DNTF, which is in the range of 120—150mm, but the detonation transition time is greatly prolonged. Composition B explosive can only be ignited when the ignition charge amount is 2.0g, and the combustion to detonation process is not completed, showing that for DNTF explosive, different ignition conditions have significant effect on the low-speed heat conduction combustion stage in the DDT process.

In order to apply additive manufacturing technology to explosive forming and preparation, and solve the problem of diversification and abnormity of warhead charge which is difficult to be realized by conventional means, the 3D direct writing process and automatic dispensing machine were used to complete the printing and forming of HMX and HMX/Al samples. Rheometer was used to test the effect of different solid contents on the rheological properties of the printed slurry, and the printing parameters were optimized. The thermal decomposition properties, microstructure and detonation properties of the printed grain were tested. The results show that the slurry with solid content of 80.0%—87.5% has the effect of shear thinning and the characteristics of composite pseudoplastic fluid, which can meet the printing requirements. The decomposition peak temperatures of HMX is advanced from 288.2℃ to 244.4℃ and 235.5℃ respectively by using GAP/N100 as binder slurry and adding aluminum powder. When the solvent of HMX slurry is 5—6g, the printing pressure is 8—13psi, and the solvent of HMX/Al slurry is 2—3g, the printing pressure is 10—16psi, and the printing rate is 10mm/s, the forming effect is good. There are no obvious cracks and pores in the 3D printed grain. The average density of HMX grain is 1.67g/cm³, and the average detonationn velocity is 7662.9m/s. The average density of HMX/Al is 1.72g/cm³, and the average heat of explosion is 7359.41kJ/kg.

To improve the energy and insensitivity of general blasting explosives, the combination of insensitive explosive TKX-50 and high-energy explosive CL-20 was selected as the main explosive. The distribution ratio of each component in the mixed explosive was determined by analyzing the effect of the content of TKX-50, CL-20, and Al on detonation properties. On this basis, the pressed TKX-50-based general blasting explosive(TCL-5)with 33%TKX-50/30%CL-20/27%Al/4%AP/6% binder was prepared through recrystallization of the main explosive, grading of the particle size and design of the composite insensitive binder carrier. Mechanical sensitivity, energy and insensitivity performance were tested according to the GJB-772A standard. The results show that the mechanical sensitivities of TKX-50 and CL-20 are significantly reduced after recrystallization. TCL-5 has a charge density of 1.95g/cm³, detonation velocity of 7895m/s, and detonation heat of 8567kJ/kg, which can pass the four insensitive tests of fast cook-off, slow cook-off, bullet impact and fragment impact. Hence, TCL-5 is a kind of high-energy insensitive explosive with higher energy and lower sensitivity, which exhibits excellent comprehensive properties.

To investigate the bubble pulsation and water jet characteristics under the gas-liquid-solid multiphase coupling effect of underwater explosions near the seabed, the Euler method was employed to establish a numerical model of underwater explosions near the seabed under different substrate/water depth conditions. The full physical process of underwater explosions near the seabed under muddy substrate conditions was simulated and compared with experimental results, which showed good agreement, verifying the effectiveness of the algorithm in solving the problem of underwater explosion bubbles near the seabed. Based on this, the influence of seabed substrate and water depth on the bubble morphology, radius, period, and water jet of underwater explosions near the seabed was discussed. The results show that under the premise that the bubbles can be split, the harder the substrate, the faster the bubbles split, and the deeper the water depth, the slower the bubbles split. The harder the substrate and the deeper the water depth, the smaller the maximum radius and period of the bubble, the larger the proportion of the bubble in the total bubble volume at the moment of splitting, and the smaller the peak velocity of the two water jets generated by splitting. During the evolution of the downward water jet, a reverse water jet will form. The harder the substrate, the greater the peak velocity of the reverse water jet. In all calculated cases, the depth parameter(H_ref)is in the range of 250—750, and the peak value of the reverse water jet velocity is positively correlated with the H_ref, and the H_ref is in the range of 750—1000, which is negatively correlated.

In order to study the explosion shock wave propagation law of triacetone triperoxide(TATP)in the air, Raman spectrometer, Fourier transform infrared spectrometer(FTIR)and gas chromatography-mass spectrometry(GC-MS)were used to inspect the structure of homemade TATP. Then the parameters of the explosion shock wave of TATP in the air were tested by the shockwave test system. The variation of peak overpressure, positive pressure duration, specific impulse and shock wave velocity with proportional distance was analyzed. The empirical formulas of peak overpressure, positive pressure duration and impulse of TATP were fitted, and the TNT equivalent of TATP was calculated. The results show that the peak overpressure and specific impulse of TATP decrease with the proportional distance, and the attenuation amplitude also decreases with the proportional distance. The measured average values are 0.87 times and 0.73 times that of TNT, and the TNT equivalent of TATP is 75.39%; The positive pressure duration is affected by both the charge mass and the charge distance. The greater the charge mass and the distance, the longer the positive pressure duration. The average rising rates of the positive pressure duration of TATP and TNT with the proportional distance are 0.066 and 0.100, respectively. In the near field, the positive pressure duration of TATP is longer than that of TNT, and when the proportional distance is greater than 3.646m/kg^1/3, its positive pressure duration gradually decreases smaller than that of TNT. It shows that the explosion shock wave parameters of TATP in the air follow the explosion similarity law, and the empirical formulas obtained by fitting is suitable for the evaluation and theoretical calculation of TATP explosion power.

To study the damage effect and mechanism of the coated reactive material fragment impacting on the double-layer aluminum plates, a 14.5mm ballistic gun was applied for the penetration experiment of steel fragments and steel-coated reactive material fragments with the same mass and size on 3mm+3mm double-layer aluminum plates under different impact velocities. The ignition and damage mechanism of the reactive material fragment impacting double-layer aluminum plates was analyzed. The results indicate that at the impact velocity of 491—1391m/s, it has the same mechanism for the two kinds of fragments. Moreover, the perforation pattern presents circle and punch, and the hole diameter and its change with the impact velocity are also similar. With the impact velocity greater than 947m/s, the perforation diameter of the rear plate is significantly greater than that of the front plate. It is mainly because intense chemical reaction is released between the plates, the higher the impact velocity, the stronger the chemical reaction, and the significant the damage enhancement effect of the rear target. When the impact velocity is 947—1391m/s, the average perforation area of the rear target is 4.1 times the cross-sectional area of fragment, and the maximum section area is 7.2 times. The velocity of the reactive fragments impact ignition threshold in this case is 947m/s.

Personnel are a critical factor in warfare.The damage effects of three types of damage elements,namely,shock wave,thermal effect and fragments,against personnel,are assessed based on the anti-personnel criterion through numerical simulation,experiment and theoretical computation tools.A damage zone of shockwave overpressure against personnel is delineated,and the relationship between scaled blast distance and personnel damage level is established,resulting in the minimum scaled blast distance of damage to personnel being 8.155m/kg^1/3.The spatial distribution of explosion thermal effect is calculated,and the free-field non-fuel air explosive or thermobaric bombs are not suitable for separate assessment of thermal effect on the personnel killing effect is put forward.The generation process of fragments is numerically simulated to obtain the quality,quantity and velocity of fragments.The simulated results are compared with the theoretically calculated results to assess the damage effect of the specific kinetic energy of fragments to personnel.The conclusions can provide reference for the design of warhead and the protection of battlefield personnel.

The damage effect of prestressed T-shaped beam under blast load is studied.A 1:3 complex steel-concrete structure finite element model of prestressed T-shaped beam is established by using nonlinear finite element software.The mesh size matching and coordination between reinforced beam elements and solid concrete elements are designed,along with the coupling among the prestressed steel strand,beam rib reinforcement,edge plate reinforcement and cross-beam reinforcement.Then cooling prestressed contraction method are used to flexibly control the accurate loading of value transfer between prestressed and T-shaped beam elements.The finite element simulation results are compered with the experimental results.The comparison result indicates that the numericial simulation and experimental damage situations are basically consistent,and at the same position,the relative error between the simulated value of shock wave overpressure and the test value is less than 20%,which verifies the effectiveness of the numerical simulation model.It can provide the simulation methods and data support for the vulnerability analysis and explosion resistance design of subsequent steel-concrete frame structures.

The problem of impact damage widely exists in various types of weapons and equipment,and seriously affects their use and lifespan.Currently,there is no universally applicable basic model for virtual experimental research on impact damage.This article focuses on the construction of basic model for impact damage virtual testing,and discusses the basic principles of smooth fluid dynamics and the application of its numerical simulation method in impact damage virtual testing.An improved smoothed particle hydrodynamics(SPH)numerical calculation model is constructed,and the particle processing and material boundary treatment of physical models are discussed in detail.Simulation calculations are conducted on the impact of typical rigid particles on the impact copper target plates,verifying the reliability and accuracy of the simulation.The damage situations of target plates impacted by the rigid particles with different edges and angles are compared and analyzed,fully demonstrating the applicability of the SPH method in virtual impact damage testing.

As the main platforms in maritime warfare,the warfare ships face various threats,among which underwater explosion is the most destructive one.In order to study the structural damage and dynamic response characteristics of ship under underwater explosion,a simplified model of Arleigh Bruke-class destroyer is established,and the underwater explosion is numerically simulated using nonlinear finite element software.The process of ship damage at different explosion distances and the overload acceleration at key locations are analyzed.The results show that the large local damage fracture of ship is the main damage form of near-field underwater explosion,and the whole whiplash movement of ship is the main damage form of far-field underwater explosion.

The air shock waves, fragments, thermal radiation, explosion effects and propagation patterns of explosive system, as well as the allowable levels that personnel, equipment and other burning explosives in the explosive system can withstand are analyzed, and the typical engineering protective measures for explosive manufacturing are discussed. These measures include sealed anti-explosion structures, personnel shelters, protective barriers, and safety distances. Based on engineering practice experience, with the aim of saving land resources and further balancing the effectiveness and economic rationality of engineering protection, it is proposed that the following issues need to be continuously studied and improved: the quantitative evaluation method for combustion and explosion effects in different scenarios, the quantitative evaluation method for the degree of destruction caused by accidents, and the risk-acceptable criteria and quantitative evaluation and optimization method for the effectiveness of engineering protection measures.

For the prediction of damage effect of reinforced concrete (RC)bridge piers subjected to explosion,the effects of explosive equivalent,explosion distance,explosion height,pier diameter,longitudinal reinforcement rate,hoop reinforcement rate,axial compression ratio and other parameters on the damage pattern and residual bearing capacity of RC bridge piers are discussed in detail through numerical simulation,and the damage law and residual bearing performance of a typical land-based RC bridge pier under the action of explosion load are obtained.As the explosion height increases,the ground reflection effect is weakened so that the residual bearing capacity increases,and an appropriate increase in the axial compression ratio can enhance the residual bearing capacity of bridge pier.By using the sub-coefficient method and taking the residual bearing capacity of RC bridge piers after explosion as an indicator,a formula considering a wide range of explosion parameters,the bridge pier component parameters and the initial stress state is proposed for calculating the damage effect of round RC bridge piers,which can quickly predict the damage of typical bridge piers subjected to explosion.

Using the method combining experiments and numerical simulations, the dynamic behavior of explosion bubbles for the cylindrical charges with different length-diameter ratios(L/D)under fixed square plates was studied. Explosion tests of TNT explosives with the mass of 2.5g and L/D of 1:1 and 2:1 under a fixed square plate was carried out, and the evolution of explosive bubbles was recorded by the high-speed camera. ABAQUS software was used to numerically simulate the underwater explosion bubble evolution process of cylindrical charges with L/D of 5:1, 10:1, and 20:1 under vertical and horizontal settings. The results show that there is no obvious difference between the explosion of 2.5g TNT explosives with a L/D of 1:1 and 2:1 under the board. When the explosives are placed vertically, the difference in the initial shape of the explosion bubble caused by different L/D of the explosives will be quickly eliminated during the evolution of the bubble. Moreover, the L/D and the starting position have effects on the water jet. When the explosives are placed horizontally, the symmetry of the bubble and the shape of the water jet will be affected by the location of the initiation point. To be specific, for the detonation from the end face, there is a slight asymmetry in the process of the bubble expansion, and the jet is offset in the direction of the starting point. Moreover, the larger the L/D of the explosives, the wider the water jet in the explosion bubble, and the smaller the load of the water jet. For the detonation from the center, the explosive bubble forms a vertical water jet without offset.

The response characteristics of cylindrical shell charge under the collaborative impact of multiple explosively formed projectiles (MEFPs) are studied. The response characteristics of cylindrical shell charges with different densities are analyzed by using a combination of theoretical calculation and numerical simulation based on impact detonation tests. The results indicate that the density of MEFPs, λ, and the thickness of cylindrical shell wall both affect the response characteristics. When λ is the same, the initiation time t increases synchronously with the increase in the thickness of cylindrical shell wall. The initiation time for the three wall thicknesses is increased by 2.00, 2.50, and 1.88 times, respectively. Especially when λ is 8 and 5.33, the initiation time shows a linear growth pattern; when h is the same, the initiation time t increases synchronously with the decrease in λ. The initiation time for the four spacings is increased by 2.66, 3.60, 3.25, and 2.50 times, respectively. Moreover, when h is 13 mm, the initiation time also shows a linear pattern.The synergistic enhancement effect of MEFPs on cylindrical shell charges is differentiated when h is 13 mm. When λ is 18 and 8, the impact initiation time of MEFP on a target is earlier than that of any single explosively formed projectile (EFP) , with a maximum advance of about 41.22% and 8.61%, respectively, indicating a significant synergistic enhancement effect. When λ is adjusted to 4, the initiation ability of MEFPs on the cylindrical shell charges gradually converges with that of a single EFP, and the synergistic enhancement effect weakens.

In order to meet the urgent need of factories to carry out the safety and risk classification and grading management for burning explosives production equipment, a risk probability and risk consequence evaluation system for the production equipment is established based on the existing risk evaluation theory according to the characteristics of military industry. The correction and quantification methods are studied for the comprehensive influencing factors, such as energetic materials, production process, equipment, safety and compensation measures,and accident consequences, and the analysis process and calculation method are established for the mechanical hazard coefficient of production equipment, the hazard coefficient of control system and the evaluation indexes of risk and consequence under the condition of the combustion and explosion shockwave. The correction coefficients of the danger of production process, the casualties and the real danger are introduced to form a new hazard evaluation methodby us for burning explosives production equipment. On this basis, 52 production equipment in typical production lines are selected for the analysis and verification of risk evaluation. The results of equipment measurement and grading coincide with the existing equipment risk management level of a production unit by 100%, which proves the effectiveness of the proposed method for evaluating the risk of the production equipment.The hazard evaluation method for burning explosives production equipment can effectively support the military enterprises to carry out the lean and professional management of the safety and risk of the production equipment.

The size of micro-charge (copper azide) and the thickness of metal flyer are the key factors affecting the reliability of fuze micro-explosive train. A detonation transfer/explosion-proof energy transfer/suppression model of metal flyer micro-explosive train driven by micro-charge is constructed, and a design method for micro-explosive train with size boundaries, such as micro-charge size and metal flyer thickness, is proposed. The research results indicate that the speed of metal flyer(2 200 m/s) increases slowly when the diameter of micro-charge is greater than 0.8 mm. When the height of micro-charge is greater than 0.5 mm, the metal flyer moves at a stable speed, which can reliably detonate the next charge. When the size of micro-charge is constant, the speed of metal flyer decreases with the increase of its thickness. The thickness of the flyer increases from 25 μm to 50 μm, which can realize the reliable detonation of micro-explosive train. Through the simulation analysis of explosion-proof slider thickness of MEMS fuze security mechanism, it is verified that the 0.2 mm-thick nickel-based slider can stably realize the explosion interruption, and the detonation transfer/explosion interruption design boundaries of flyer-type fuze micro-explosive train are finally formed.