Hasil untuk "Explosives and pyrotechnics"

Liefeng SHOU, Wenjun ZHU, Qinchao LI et al.

A compressible multiphase flow numerical scheme, induced from the multi- component diffuse interface model with arbitrary number of materials, is established to simulate the interaction between distinct materials under extreme conditions. A robust, low dissipation and high efficiency reconstruction method, the MTBVD (muscl thinc boundary variation diminishing), is proposed with the aid of artificial intelligence technology, which can adaptively select the most suitable reconstruction method in the essential regions such as shock wave, contact discontinuity and material interface, and can achieve the minimum global numerical dissipation. Furthermore, it has a higher computational efficiency than the traditional BVD (boundary variation diminishing) scheme. The automatic geometric modeling and grid meshing based on global geographic information system, adaptive mesh refinement and large-scale parallel computing method are established to realize the whole numerical simulation of shock wave propagation in complex terrain and real urban environments. Our schemes allows for the effective simulation of intense blast wave scenarios on a large scale within intricate urban settings, employing billions of meshes, a pressure spectrum ranging from 103 Pa to 1015 Pa, and a minimum spacing size of 10 km. We have conducted multiple numerical simulations that demonstrate the propagation of blast waves through complex landscapes and urban areas, which corroborate our methodologies.

Ding CHEN, Zeyang YU, Xuehao YAO et al.

The evaluation method of ship’s explosion shock resistance is challenged by some key mechanical problems, such as strong nonlinear fluid-structure coupling, large-deformation and failure evolution of solid structure. By coupling the respective advantages of peridynamics (PD) and smoothed particle hydrodynamics (SPH), an efficient PD-SPH numerical method suitable for underwater explosion shock simulations was developed. The SPH method was employed to simulate underwater shock wave propagation and fluid-structure interaction, while the PD method accurately characterized the complete mechanical behavior of solid structures from elastic deformation to progressive damage failure. A PD-SPH numerical model was established for non-explosive underwater shock loading devices. In the non-ordinary state-based peridynamics (NOSB-PD) framework, the Johnson-Cook damage model was introduced. To suppress the occurrence of numerical instability, the artificial stiffness form was introduced by increasing the internal constraints between particles. To improve the computational efficiency in large-scale simulations, a multi-GPU (graphics processing unit) parallel computing framework based on domain decomposition and data-communication mechanisms was established. The domain decomposition was carried out through the Eulerian format. When particles move from one domain to another, the physical quantities of the particles were exchanged for information. Model validation and parallel efficiency tests demonstrate that the proposed method can accurately predict shock wave wall pressure and target dynamic deformation, successfully reproduce typical crack propagation patterns in thin-plate structures and simulate the entire damage process of complex grid sandwich structure. In complex fluid-structure coupling scenarios with more than 5 million particles, the 8*RTX4090 achieved an acceleration ratio of 4.13 compared to a single RTX4090, with a parallel efficiency of 51.6%. The actual computation time can be reduced to nearly 1 hour. Meanwhile, compared with traditional CPU (central processing unit) parallelism, the multi-GPU parallelism can achieve an acceleration ratio of more than 9 times. The research outcomes provide a high-precision and efficient numerical analysis tool for the design of explosion-resistant naval structures, offering significant reference value for engineering applications of fluid-structure interaction in underwater explosion problems.

Linfu Yi, Xiao Liu, Jun Hou et al.

The mechanical properties of new propellants are an important basis for studying the internal stress propagation and damage mechanism of barreled weapons during use. Taking the porous special-shaped boundary propellant as the research object, Quasi-static compression experiments are conducted at different temperatures and different compression rates. Combined with stress-strain data, the effects of temperature and compression rate on the mechanical properties of the selected propellant are explored. At the same time, based on discrete element theory and EDEM simulation software, a simulation model with a porous special-shaped boundary structure can be established, then the Quasi-static compression experiment is simulated. The simulation result shows that the established simulation model can describe the stress propagation and deformation process of the propellant well under Quasi-static compression at 20 °C. It provides an effective theoretical model basis for studying the damage mechanism of propellant in the barrel of barrel weapons.

Rongxin LI, Jialin CHEN, Ruiqi WANG et al.

High-entropy alloys (HEAs), as a novel class of high-performance metallic materials, have demonstrated considerable potential in the fields of damage and penetration mechanics. This study investigates the application of CoCrFeNiCux HEAs as liner materials for explosively formed projectiles (EFPs), with the objective of enhancing EFP formation quality and damage efficacy through structural optimization of the liner. Quasi-static and dynamic tensile tests were conducted to characterize the mechanical properties of the HEAs with different copper contents (x=0 and x=1). The experimental data were used to fit parameters for the Johnson-Cook (J-C) constitutive model. The results indicate that both HEA compositions exhibit outstanding plasticity, ductility, and positive strain-rate sensitivity, with dynamic yield strength increasing significantly under high strain-rate loading. Numerical simulations were performed using the nonlinear finite element software AUTODYN to compare the EFP formation processes between conventional copper liners and the proposed HEA liners. The simulations revealed that the superior strength of the HEAs impeded the complete closure of the projectile tail when using a conventional uniform wall thickness liner geometry. To address this issue, a uniform variable wall thickness design was implemented for the HEA liners. This optimization successfully improved the formed EFPs, resulting in length-to-diameter ratios of 2.0 for x=0 and 2.5 for x=1, with velocities reaching 2260 m/s and 2357 m/s, respectively. The penetration performance of the optimized HEA EFPs was validated against two target types. The projectiles achieved penetration depths of 37.8 mm (x=0) and 41.5 mm (x=1) into 100-mm-thick 4340 steel targets, and 287.6 mm and 303.7 mm into 1000-mm-thick C35 concrete targets. The crater diameters exceeded 260% of the charge caliber, confirming excellent penetration and damage capabilities. This work demonstrates that structural optimization of CoCrFeNiCux HEA liners significantly enhances EFP formation quality and penetration performance, providing a theoretical foundation and a novel strategy for the design of high-efficiency damage warheads.

Lin Zhong, Hao Li, Qi-fa Yao et al.

While 3D printing technologies based on various curing methods like thermal curing, photopolymerization, solvent evaporation molding, and melt cooling have been extensively studied in the field of composite energetic materials (CEMs), recent advancements in multi-material, multi-nozzle, and acoustic resonance techniques are now enabling the fabrication of CEMs with highly complex architectures and novel formulations, including polymer-bonded explosives (PBX), propellants, and pyrotechnics. 3D printing provides a more convenient and reliable approach for the structural design and study of the structure-performance relationship in CEMs, which is challenging to achieve through traditional subtractive or equivalent material manufacturing. UV-curing 3D printing, as a rapid-curing 3D printing method, offers advantages such as superior safety, efficiency, and environmental friendliness over other methods, garnering significant attention in the 3D printing of CEMs. This paper focuses on UV-curing technology and provides a detailed overview of the research progress on various UV-curing 3D printing techniques in the field of CEMs. It also discusses the advantages of 3D printing in the design of structured CEMs charges. Finally, based on the current research status of 3D printing for CEMs, we summarize some existing issues and present our perspectives on future development trends.

Yun Zhang, Runqing Liu, Weiguo Cao et al.

To investigate the thermal stability of RDX-CMDB propellant and HMX-CMDB propellant, the behavior of thermal decomposition was assessed using differential scanning calorimetry. The thermal safety characteristic parameters were calculated by the Ozawa method, and flame sensitivity and mechanical sensitivity tests were conducted to obtain the 50% ignition height, critical impact energy, and critical friction load. Molecular dynamics simulations were employed to analyze the trigger bond length and cohesive energy density (CED) of NC/NG, NC/NG/RDX, and NC/NG/HMX systems. The experimental results showed that as the contents of RDX and HMX increased, the first exothermic peak temperature of propellants was shifted to a higher temperature, and the second decomposition peak temperature of HMX-CMDB propellant was increased by 18.90 °C, thermal safety was increased. The flame sensitivity decreased by 0.74 cm and 1.32 cm, respectively, the friction sensitivity increased from 73 N to 96 N and 108 N, respectively, and the impact sensitivity remained almost unchanged. The simulation results showed that with the increase of the content of HMX and RDX, the trigger bond length of the system gradually decreased. The CED gradually increased, and the thermal stability of the system was enhanced.

Sebastian Górecki, Agnieszka Kudelko

Nitrogen-rich heterocycles constitute a family of high energy density materials (HEDMs) that have been developing intensively in recent years. A representative of this class is 1,2,4,5-tetrazine, a six-membered aromatic compound containing four nitrogen atoms in the ring. Many energetic compounds with this scaffold exhibit thermal stability, high density, and insensitivity to various stimuli, including friction, impact, and electrostatic discharge. This review presents methods for constructing 1,2,4,5-tetrazine precursors from acyclic reagents and describes their chemical modifications, leading to new energetic compounds with potential applications in the industry as explosives, propellants, or pyrotechnics. Synthetic procedures and reaction conditions are discussed, along with the detonation parameters of new nitrogen-rich tetrazine-based products, which allow estimation of their application potential.

Hongwei Gao, Hongsheng Yu, Yue Tang et al.

Low regression rate due to difficult pyrolysis is a major challenge in the practical application of terminated hydroxyl‑terminated polybutadiene (HTPB)-based fuels in hybrid rocket propulsion. Accelerating the decomposition of the polymer matrix is an effective method to improve the regression rate of HTPB fuels. To determine the difference in combustion performance between different transition metal oxides loaded HTPB-based fuels, nickel oxide (NiO), ferric oxide (Fe2O3), copper oxide (CuO) and manganese dioxide (MnO2) were introduced into the HTPB matrix at 5% mass fraction. The experimental results showed that the metal oxides could significantly catalyze the pyrolysis of HTPB-based fuels and enhance the fuel regression rate, and the catalytic effect was mainly concentrated in the middle and late stages of the thermal decomposition process of polybutadiene components. Among the four transition metal oxides, CuO and MnO2 showed better catalytic effects on the combustion performance of HTPB-based fuels in the high oxygen mass flux region, while NiO showed better catalytic effects in the low oxygen mass flux region. The present study compares the regression rate of fuel grains modified with different transition metal oxides, which provides a basis for the selection of future catalysts, verifies the catalytic effect of the transition metal oxides on the combustion of HTPB-based fuels and further analyzes the combustion reaction mechanism of the fuels.

Zhenguo Pang, Kaitian Zhu, Lingzhi Zhang et al.

Electrically controlled solid propellants (ECSP) have attracted extensive attention due to the tunable burning rate. The burning rate of ECSP determines the applying background of propellants and rocket engine structural design. Herein, an ECSP named ECSP was prepared using HAN as the oxidizer, PVA as the binder and self-developed electric controlled PCH as the fuel. It was investigated that the influence of pressure, initial temperature and voltage on the burning rate of the propellant. The results indicate that the pressure index n of ECSP is 0.36, the temperature sensitivity coefficient σP is 0.005 K-1. Under certain conditions, the burning rate of ECSP varies linearly with voltage, and the maximum regulation range is higher than 39%. Fitted the burning rate equation of ECSP with the voltage parameter based on Vielle’s burning rate equation, the consistency between the actual chamber pressure of the ECSP in the prototype and the predicted pressure by the burning rate equation was verified.

Yuchun ZHANG, Wen YANG, Kun ZHANG et al.

Coal-to-hydrogen is an effective solution for the low-carbon transformation of coal energy. However, transporting hydrogen via the natural gas pipeline network poses significant explosion safety challenges. To address these concerns, the effect of non-premixed CO2 injection on the explosion characteristics of hydrogen-doped natural gas was investigated. An experimental explosion platform was independently designed and constructed to actively release CO2 into the hydrogen-doped methane explosion via a high-pressure gas injection device. The CO2 injection was initiated prior to ignition, creating a non-premixed turbulent atmosphere. The volume of CO2 injection was controlled by injection pressure (0, 0.5, 0.75, and 1.00 MPa) and injection time (0, 60, 120, and 180 ms). The dynamics of explosion flame propagation and pressure behavior under non-premixed CO2 injection were analyzed. Results showed that injection pressure and injection time significantly influence the premixed explosion process. The injection of non-premixed CO2 into the premixed explosion induces turbulence, causing flame wrinkling. Structural changes in wrinkled flames increase the flame surface area, leading to accelerate flame propagation and enhance explosion intensity. For a given injected time (e.g., 0 or 120 ms), increasing the injection pressure introduces more CO2, which enhances localized turbulence and disturbance in the flame, leading to further flame acceleration and more severe explosion consequences. As the injection time increases, the maximum explosion pressure of different injection pressures increases and then decreases. CO2 injection in the explosion plays a competitive relationship between turbulence promotion and dilution effect, with a critical injection time. Excessive CO2 injection can enhance its dilution effect, weakening the CO2 injection on the explosion of turbulence perturbation ability, which reduces the explosion intensity. Moreover, a higher injection pressures correspond to shorter injection time. Meanwhile, the maximum explosion pressure at larger injection pressures is more sensitive to changes in injection time. Injection pressure and injection time are the key parameters governing the impact of CO2 injection on the explosion hazard of hydrogen-doped natural gas. The findings provide fundamental guidelines for the safety prevention and control strategy of hydrogen transportation in the natural gas pipeline network.

Kehui WANG, Long MENG, Ming LI et al.

Two kinds of structural projectiles made of two different materials were designed in this paper. An experimental study of 11 kg projectiles penetrating the reinforced concrete target at 1400 m/s was carried out using a 203 mm Davis gun. Based on the experimental results, the structural response, penetration capability and related engineering issues of the projectile are discussed. The results show that when the reinforced concrete target is penetrated at a velocity of 1400 m/s, the heads of projectiles made of two different materials experienced erosion and were mushroomed. This was caused by high temperatures resulting from friction between the projectile and the concrete during penetration, which significantly softened the surface of the projectile. Furthermore, the contact pressure between the projectile and the target exceeded the yield strength of the projectile material near the surface, causing the material to enter a state of plastic flow and ultimately leading to the erosion and mushrooming of the projectile head. Additionally, the surface material of the projectile was stripped due to the cutting action of the hard aggregates in the concrete, resulting in severe abrasion of the projectile body. When comparing the structural responses of projectiles made of different materials, it was evident that material properties influenced their behavior. Compared to 30CrMnSiNi2MoVE, DT1900, known for its higher strength, hardness and better resistance to impact compression, showed less erosion at the projectile head. However, the inferior shear resistance and wear resistance of DT1900 led to severe abrasion on the projectile body. The mass loss pattern of a conical projectile is different from that of a solid long-rod projectile, with the latter concentrated mainly in the projectile body. The conical flared tail design, while suppressing ballistic deflection, increased the contact area between the projectile body and the target, enhancing the abrasive and cutting actions of aggregates and steel. Moreover, under high-speed penetration conditions, the erosion and mushrooming of the projectile head could reduce the penetration depth; the less erosion at the head, the greater the penetration depth. In experiments, the maximum penetration depth of DT1900 projectiles could reach up to nine times the length of the projectile.

Ning DU, Shichao REN, Huameng FU et al.

To investigate the explosive energy release of Zr-based reactive material (Zr-RM) casings and the ignition effect of fragments driven by the explosion on fuel, casings composed primarily of zirconium (Zr), copper (Cu), nickel (Ni), aluminum (Al), and ytterbium (Y) were fabricated using alloy melting and casting techniques. The casings mentioned above had an outer diameter of 40 mm, a height of 80 mm, and a wall thickness of 5 mm. For comparison of subsequent damage effects, steel casings made of 45 steel with the same dimensions and mass were also prepared. Both types of casings were filled with JH-2 explosive charges. The charged structures were placed on a polyvinyl chloride pipe stand 1.5 m above the ground, and a fuel box containing 2.5 L of gasoline was positioned 2.0 m away from the explosion center. During the explosion-driven tests, a high-speed camera was utilized to capture the formation and propagation of the explosion fireball, the shockwave, and the impact process of casing fragments on the fuel tank. The fireball duration, shockwave velocity, and fragment impact effects were measured and analyzed. Additionally, the ignition and destruction effects of the fragments on the fuel were observed and recorded. The experimental results demonstrate that, when compared to steel casings of equal mass, Zr-RM casings under explosion-driven conditions exhibit a longer duration of firelight and faster shockwave velocities. Specifically, the fireball duration of Zr-RM casings is approximately 25.84 times that of steel casings, and the shockwave velocity is roughly 1.17 times faster. Zr-RM casings exhibit an enhancement effect on air shockwaves under explosion-driven conditions. Fragments of different materials cause structural damage to fuel tanks, including perforation and plastic deformation. After piercing the fuel tank, the reactive material ignites the fuel inside, demonstrating the ability to ignite gasoline. On the contrary, steel casings of equal mass do not ignite the fuel within the tank. This research provides a reference for the application of Zr-RM casing warheads.

Liwenying Yang, Ming Li

By introducing a simple competition mechanism for bond insertion in random graphs, explosive percolation exhibits a sharp phase transition with rich critical phenomena. We investigate high-order connectivity in explosive percolation using an event-based ensemble, focusing on biconnected clusters, where any two sites are connected by at least two independent paths. Our numerical analysis confirms that explosive percolation with different intra-cluster bond competition rules shares the same percolation threshold and universality, with biconnected clusters percolating simultaneously with simply connected clusters. However, the volume fractal dimension $d_{f}'$ of biconnected clusters varies depending on the competition rules of intra-cluster bonds. The size distribution of biconnected clusters exhibits double-scaling behavior: large clusters follow the standard Fisher exponent derived from the hyperscaling relation $τ'=1+1/d_{f}'$, while small clusters display a modified Fisher exponent $τ_0<τ'$. These findings provide insights into the intricate nature of connectivity in explosive percolation.

Haolong Meng, Baoxing Li, Guiyang Xu et al.

To investigate the characteristics of rotating detonation waves fueled by liquid kerosene with increasing equivalence ratios, the experiments were performed through increasing the supply of liquid kerosene under three different mass flow rates of oxidizer. Various mode transitions were realized, including transition from unstable detonation to stable single-wave mode, transition from unstable detonation to stable double-wave mode and transition from double-wave mode to single-wave &amp; double-wave hybrid mode. The results demonstrate that the increase of equivalence ratios leads to the improvement of mixture reactivity under lean-fuel limit, which enhances the propagation stability and pressure peak of rotating detonation waves, and then results in the transition from unstable detonation to a stable propagation mode. In addition, when the mass flow rate of oxidizer is approximately 1100 g/s, the transition from double-wave mode to single-wave &amp; double-wave hybrid mode is observed by increasing the equivalence ratio from 0.6 to 0.93. It is concluded that the mutation of dynamic balance between the RDW and injection plenum caused by the increasing of equivalence ratio is one of the reasons inducing the mode transition. This work illustrates the feasibility of modulating the propagation mode in rotating detonation waves fueled by liquid kerosene, and promotes the application of rotating detonation engine.

Bambang Sardi, Irianto Uno, Felix Pasila et al.

Not only its abundant resources, but also low rank coal (LRC) can be transformed into different valuable chemical products via syngas. This review focuses on technology of microwave-assisted pyrolysis (MAP) applied on LRC as a promising technique of thermochemical conversion that can transform LRC into high quality syngas. A confined number of reviews has been selected and evaluated to observe current status and challenges of the technology, including essential production factors, pretreatment of LRC, and heating characteristics of MAP. Experimental research on catalytic and non-catalytic of the technology focusing on the product distribution resulting from conventional pyrolysis (CP) are also discussed. The best yields of char, tar, and syngas from CP at 900 °C were 2%, 41%, and 58%, respectively. Meanwhile, the best yields of char, oil and syngas from MAP at 620 °C were 32%, 15% and 53%, respectively. Finally, this review evaluates the advantages and challenges of the technology and the milestones to be achieved in near future.

Chunhai Yang, Xue Li, Ning Zhou et al.

The two directly substituted pentazoles, N5NH2 and N5COOH, were designed to theoretically study the relationships between substituents, aromaticity and kinetic stability thereof. Analysis shows their kinetic stability order described by the energy separations between the highest occupied molecule orbital (HOMO) and the lowest unoccupied molecule orbital (LUMO), viz. HOMO-LUMO gap, is line with the aromaticity orders obtained from nucleus-independent chemical shift (NICS), harmonic oscillator measure of aromaticity (HOMA), Bird aromaticity index (I) and isochemical shielding surface (ICSS), which is N5NH2 > N5COOH. But this order is contrary to the heat stability order according to Ref [1] The inconsistency between heat stability and kinetic stability reveals the fact that stability of compounds is a complex character and different according to the compound property of the study. The consistency of kinetic stability order with the aromaticity orders described by NICS, NICSSZZ, HOMA, I and ICSS indicates these widely accepted methods for aromaticity estimating are reliable for the two given compounds. As for the effect on aromaticity of pentazole ring from substituent, electron-donating substituent have stronger effect than electron-withdrawing substituent.

K.A. Monogarov, D.B. Meerov, I.V. Fomenkov et al.

Impact sensitivity of energetic material is considered to be not an intrinsic property of the compound, but to depend on multiple variables, including, in addition to chemical nature of the substance, both the powder and the instrument-depending factors. Therefore, the comparison of the sensitivity data obtained using different impact machines and measurement protocols, and even by the same ones but in the different laboratories is difficult. Based on the works carried out almost 90 years ago, we propose a relatively simple but versatile technique using the modified standard fallhammer to measure the drop weight speed in downward and upward directions. The combination of the tests without sample and with sample of energetic material (both for the “triggered” and “not-triggered” cases) allows obtaining the energy transferred to and absorbed by the sample at the weight-height load, corresponding to the reaction threshold. An energy balance during the impact event is calculated to show the importance and the maintenance-dependency of the energy losses stored in test machine, and to illustrate the difference between the full energy value and the actual energy absorbed by the sample. One of the outputs of the suggested procedure are the values of energy absorbed by the sample at reaction threshold. These values are obtained in the course of standard testing protocol, in addition to the nominal drop energy value, corresponding to 50% probability of the reaction initiation. The suggested “real” energy values represent more relevant measure of mechanical hazard than usually reported nominal drop energy values.

Manman Li, Rui Hu, Yuchen Gao et al.

In this work, energetic composite composed of UV curable polyurethane acrylate and RDX was used as deterrent coating for 19-perforated nitroamine propellants plasticized by nitroglycerin and 1, 5-diazido-3-nitrazpentane (DIANP). The nitroamine propellant was end-sealed with the photocurable energetic composite material by using spraying and UV curing method. Combustion behaviors including burning progressivity and temperature sensitivity were studied by performing closed bomb test on propellants with 0.74%, 1.01% and 1.15% deterrent. The inner structure detection revealed that the deterrent penetrated into the perforations during coating process. The end-sealed propellant with blocked perforations exhibited inhibition of initial gas generation rate, which was demonstrated by dynamic vivacity curves. It is inspiring that the propellants coated with 1.01% and 1.15% deterrent presented excellent consistency according to the dynamic vivacity curves between 20 °C and 50 °C. Moreover. it can be indicated that the plugs in perforations conduced to temperature independence property of propellant under ambient temperature. This benefit contributes to improvement of the firing safety at high temperatures.

Tetyana Laptyeva, Sarika Jalan, Mikhail Ivanchenko

Explosive synchronization refers to an abrupt (first order) transition to non-zero phase order parameter in oscillatory networks, underpinned by the bistability of synchronous and asynchronous states. Growing evidence suggests that this phenomenon might be no less general then the celebrated Kuramoto scenario that belongs to the second order universality class. Importantly, the recent examples demonstrate that explosive synchronization can occur for certain network topologies and coupling types, like the global higher-order coupling, without specific requirements on the individial oscillator dynamics or dynamics-network correlations. Here we demonstrate a rich picture of explosive synchronization and desynchronization transitions in multiplex networks, where it is sufficient to have a single random sparsly connected layer with higher-order coupling terms (and not necessarily in the synchronization regime on its own), the other layer being a regular lattice without own phase transitions at all. Moreover, explosive synchronization emerges even when the random layer has only low-order pairwise coupling, althoug the hysteresis interval becomes narrow and explosive desynchronization is no longer observed. The relevance to the normal and pathological dynamics of neural-glial networks is pointed out.