JOB-9003炸药"激热"冲击损伤破坏及超声特征

进行了未经热处理的JOB-9003塑料粘结炸药(PBX)标准压缩试样的"激热"冲击损伤破坏试验,对试样热冲击试验前后的超声波特性参量进行了检测,试验显示出JOB-9003炸药存在一个明显的"激热"冲击损伤破坏临界温度差,并获得了试样热冲击损伤破坏的超声波参量特征.     

Shock Initiation of the CL‐20‐Based Explosive C‐1 Measured with Embedded Electromagnetic Particle Velocity Gauges

Hexanitrohexaazaisowurtzitane (CL‐20) is a high‐energy material with high shock sensitivity. The evolution of shock into the detonation of CL‐20 deserves academic attention and research. An embedded electromagnetic particle velocity gauge was used to study the shock initiation of detonation in a pressed solid explosive formulation, C‐1, containing 94 wt‐% epsilon phase CL‐20 and 6 wt‐% fluororubber (FPM). In conventional experiments, the magnetic field was generated using a pair of electromagnets with a complex structure and operation. A new device was designed to solve complex problems. This device comprised NdFeB magnets, pole shoes and magnetic yokes; using this technique, a uniform magnetic field could be created. A series of shock initiation experiments on high‐explosive C‐1 was performed, and the explosive samples were initiated at different intensity input shocks by an explosive driven flyer plate. In situ magnetic particle velocity gauges were utilized to detail the growth from an input shock to detonation, and the attenuation of particle velocity in unreacted C‐1 was also obtained in low‐intensity shock initiation experiments. Hugoniot data for C‐1 in the form of shock velocity D vs. particle velocity Up were obtained. A simulation model for shock initiation of C‐1 was established, and the particle velocity data from several experiments were used to determine the parameters required for the unreacted equation of state and ignition and growth reactive flow model for C‐1. These coefficients were then applied in the calculation of the initial shock pressure−distance to detonation relationship (Pop‐plot) for the explosive. Based on the results of experiments and simulations, the shock sensitivity characteristic of C‐1 was described.     

A Simple Theoretical Method for Determining the Sensitivity of Bare Explosives to Detonation by Projectile Impact

The Walker‐Wasley Critical Initiation Energy, E _c, cited by several authors as a means of comparing the sensitivity of explosives to projectile impact, is imprecise. Moreover, energy is not a necessary and sufficient condition upon which to compare sensitivities, since it might be delivered over picoseconds or years with vastly different results. Shock to detonation initiation conditions are conventionally represented by log −log relationships in Pop Plots. Historical experimental flat‐fronted projectile attack data for two explosives, PBX 9404 and Tetryl were transformed using Hugoniot data into log −log form like Pop Plots. Consistent with recent research at LASL and LLNL in the US, near coincidence between such plots and Pop Plots was demonstrated. This procedure led to a method of comparing the sensitivities of these and four other explosives, two types of Composition B, TNT and Nitroguanidine/Estane (95/5), to shock initiation by projectile impact. A slight modification of this procedure can be used to generate critical projectile velocity vs. diameter curves from Hugoniot and Pop Plot data which confirm the experimental data for PBX 9404 and Tetryl. An alternative comparative sensitivity criterion to that of Walker and Wasley that is derived from Pop Plot data is proposed based on the critical power per unit mass of explosive transmitted from the initiating shock.     

Calculation of Depth and Crater Diameter for the Supersonic Penetration of Shaped Charge Jet into Concrete

Considering that the sound velocity of concrete is lower than that of metal, this study discusses the effect of stationary shocks and compression during the process of shaped charge jet penetration into concrete when the penetration velocity is greater than sound velocity. The linear relationship between shock velocity and particle velocity is used to describe concrete materials. The state parameters of concrete under shock loading are calculated using Rankine‐Hugoniot jump conditions. Moreover, a combination of these relations with the Bernoulli equation yields a supersonic penetration equation across the shock. A cavity growth equation based on the Szendrei‐Held equation is presented when supersonic penetration occurs. Predictions from the supersonic penetration model are in good agreement with the depth and cavity diameter of experimental results for shaped charge jet penetration into concrete for charge diameters of 60, 142, 200, and 400 mm.     

Reaction Behavior of Polytetrafluoroethylene/Al Granular Composites Subjected to Planar Shock Wave

The shock‐compression responses of PTFE (polytetrafluoroethylene)/Al granular composites subjected to planar shock waves of various pressures are investigated. A 57‐mm diameter single‐stage gas‐gun and 50‐mm diameter plane‐wave lenses are employed to perform planar shock wave experiments. High frequency manganin piezoresistance stress gauges are used to monitor the stress (regarded as pressure in consideration of the high pressure state) at four Lagrangian positions of the PTFE/Al granular composites specimens. Planar shock wave experiments show characteristics of densification at measured input pressure of 0.5 GPa to 1.27 GPa using single‐stage gas‐gun and shock‐induced reaction (SIR) indicated by growth of shock pressure and specific volume expansion at measured input pressure of 7.29 GPa to 12.25 GPa using plane‐wave lenses. The pressure and relative volume states behind the shock wave front are calculated from the experimental recorded pressure profiles using Lagrangian analysis method, which are used to determine the reaction ratios under different shock pressures by comparing with partial reacted Hugoniot calculations. It was shown that the reaction ratios obtained in this research have good agreement with the thermochemical modeling calculations. The corresponding results indicate that the shock‐induced reactions of PTFE/Al granular composites occur in the shock wave rising period and the reaction ratios are intimately related to the shock wave pressure.     

Non-Reactive HMX Shock Hugoniot Data

Modified wedge tests and in situ pressure gauges have been used to measure the shock Hugoniot of HMX/water⁽¹⁾ mixtures. Making the assumption that the mixture is macroscopically homogeneous and isotropic, these data, and literature values for the equation of state of water, are used to deduce the Hugoniot of pure HMX. Shock strengths below 6.0 GPa produced no significant reaction near the shock front. Radiometric observation of the shocked mixture supports this conclusion. The new HMX shock velocity versus particle velocity curve is significantly below that published for solvent pressed HMX. Reactive flow hydrodynamic calculations indicate that as much as 3% – 7% HMX may have reacted in the experiments with solvent pressed material.     

The shock and release behavior of an aerospace‐grade cured aromatic amine epoxy resin

Knowing the dynamic behavior of polymer materials that are used in the construction of fiber‐reinforced composite materials is particularly important for such materials that are subjected to impact. In this work, we have conducted a number of plate‐impact experiments on a commercially important aromatic amine epoxy resin that is used in the construction of carbon fiber composite materials. The measured Hugoniot in shock velocity–particle velocity space was U_s = 2.65 + 1.55 u_p (ρ₀ = 1.141 g/cc), and is similar to the measured Hugoniots of other resins presented by different researchers. We have also measured the longitudinal stress in the shocked material and shown, in common with other polymers, that above a threshold stress, an increase in shear strength with impact stress is observed. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

JOB-9003炸药燃烧转爆轰现象研究

HMX颗粒炸药和JOB－9003炸药进行了燃烧转爆轰（DDT）实验，研究了炸药组分，装药密度以及约束条件对DDT过程的影响，分析了炸药DDT的机理，实验结果表明炸药DDT过程和炸药组分以及装药状态有很大关系。HMX颗粒炸药容量发生DDT现象，而以HMX为主要成分的JOHB－9003压装装药不容易发生DDT现象。     

Energetic Material Detonation Characterization: A Laboratory‐Scale Approach

A novel energetic‐material detonation and air‐blast characterization technique is proposed through the use of a laboratory‐scale‐based modified “aquarium test.” A streak camera is used to record the radial shock wave expansion rate at the energetic material air interface of spherical laboratory‐scale (i.e., gram‐range) charges detonated in air. A linear regression fit is applied to the measured streak record data. Using this in conjunction with the conservation laws, material Hugoniots, and two empirically established relationships, a procedure is developed to determine fundamental detonation properties (pressure, velocity, particle velocity, and density) and air shock wave properties (pressure, velocity, particle velocity, and density) at the energetic material air interface. The experimentally determined properties are in good agreement with published values. The theory’s applicability is extended using historical experimental test data due to the limited number of experiments able to be performed. Predicted detonation wave and air shock wave properties are in good agreement for a multitude of energetics across various atmospheric conditions.     

Projectile Impact Ignition and Reaction Violent Mechanism for HMX‐Based Polymer Bonded Explosives at High Temperature

Determining the mechanism of transition from projectile‐impact ignition to detonation is a complex and difficult task with strong practical applications. Ignition due to low‐velocity projectile impact cannot be properly explained by the available theories. We attempted to determine the mechanisms of initiation of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX)‐based polymer‐bonded explosives (PBXs) in a range of high temperatures, which have rarely been investigated. Comparing the shock initiation results, we found that the low‐velocity projectile impact response mechanisms for a heated explosive are much more complex. Our results show that the impact ignition threshold velocity of the heated explosive does not always decrease with increasing temperature as commonly expected. A temperature dependent plastic power during impact controls the ignition in the range of 25 °C to 75 °C. At 190 °C and 200 °C, there was a sharp rise of reaction degree induced by β→δ phase transition for high HMX‐content PBX. Conversely, such phase transition effect becomes insignificant for low (<50 %) HMX‐content PBX. Our results show that three competing mechanisms affect the impact safety for a high HMX‐content PBX at high temperature, including plastic power, temperature sensitizing, and phase transition.     

Shock Compression of Boron Carbide: A Quantum Mechanical Analysis

The shock Hugoniot of boron carbide, from 0 to 80 GPa, has been obtained using first principles quantum mechanics (density functional theory) and molecular dynamics simulation. The Hugoniot for six different structures which vary by structure or stoichiometry were computed and compared to experimental data. The effect of stoichiometry, and structural variation within a given stoichiometry, are shown to have marked effects on the shock properties with some compositions displaying bilinear behavior in the computed shock velocity‐particle velocity profiles while others show a continuous Hugoniot curve with no evidence of a phase transition over the pressure range considered in this work. Two structures, B₁₂(CBC) and B₁₁C_p(CCB), have predicted phase transition pressures lying within the 40–50 GPa range suggested experimentally. It is shown that the phase transition is driven by deformation of the 3‐atom chain within the boron carbide crystal structure which induces a discontinuous volume change at the critical shock pressure. The effect of defects, in the form of chain vacancies, on the shock response is presented and the ability of shear to significantly lower the phase transition pressure, in accord with experimental observation, is demonstrated.     

Divergent Detonation Wave Processes in PBX Based on RDX

In order to characterize the initial phase of the divergent detonation wave in PBX, a hemispheric explosive sample was initiated by a long cylindrical charge of the same explosive. The tested PBX is composed of 85 wt% of RDX and 15 wt% of binder based on HTPB. This PBX‐RDX presents an effective density of 1.57 g/cm³, and a detonation velocity of 7.90 mm/μs.     

Preparation and Properties of Submicrometer‐Sized LLM‐105 via Spray‐Crystallization Method

Submicrometer‐sized 2,6‐diamino‐3,5‐dinitropyrazine‐1‐oxide (LLM‐105) crystals were prepared by spray‐crystallization method with dimethyl sulfoxide (DMSO) and ultra‐pure water with surfactant as the solvent and anti solvent, respectively. Submicrometer‐sized LLM‐105 particles were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), and particle size analysis. The thermal stability and sensitivity properties of submicrometer‐sized LLM‐105 were also investigated. The results revealed that the submicrometer‐sized LLM‐105 particles are spherelike in morphology with a narrow particle size distribution at the range of 100–600 nm. The submicrometer‐sized LLM‐105 has a lower exothermic peak at about 343.7 °C compared with the synthesized material. Sensitivity tests showed that submicrometer‐sized LLM‐105 is more insensitive under impact stimulus with a drop height (H₅₀) of 102 cm. The submicrometer‐sized LLM‐105‐based PBX is more sensitive for short impulse shock wave that can be initiated at lower initiation current.     

炸药热冲击损伤破坏及超声波特性参量检测

进行了 JOB- 90 0 3炸药试样的热冲击试验和热冲击前后的超声波特性参量检测试验 ,观察并检测到试样在热冲击试验的不同阶段出现损伤破坏及超声波特性参量的具有一定典型性的变化。试验初步表明 ,初始损伤或裂纹对炸药的力学性能有十分明显的影响 ,超声波特征参量对炸药的损伤及破坏进一步表现出一些可识别的特征     

Equation of state of polytetrafluoroethylene for calculating shock compression parameters at megabar pressures

Semi-empirical equations of state (thermal and caloric) are obtained to calculate not only the kinematic parameters (shock wave velocity, particle velocity, and reverberation of waves) but also the thermodynamic parameters (temperature, pressure, and compression) of monolithic and porous polytetrafluoroethylene at high shock pressures. The equations of state are used to model wave interaction in shock-wave experiments using the developed hydrocode. The equations are verified by comparison simulation results with published results of experiments and the data of our shock compression tests of solid and porous samples of PTFE in the range of 10–170 GPa.     

Determining the Velocity and Specific Weight of a Particle Flow Discharged from Surfaces of Metals under a Shock-Wave Load

A heterodyne interferometer is used photon Doppler velocimetry (PDV) method to study a particle discharge from the free surface of lead samples of different roughness under a shock-wave load. In experiments, the velocity of the free surface of samples and the dust flow velocity are determined, and indicator foils and thin glasses are used to calculate the specific weight of the dust. Dependences of the specific weight of particles on their relative velocity are constructed. Effects of roughness and phase state of the substance after a shock-wave load on the possibilities to determine the velocity of the free surface and the specific weight of discharged particles using indicator foils are analyzed. It is shown that, with given surface roughness, the specific weight of dust, discharged from the surface during lead melting under the action of a shock wave or load wave, is much larger than in a sample being in a solid state.     

Effect of TiB2 on dynamic response of TiB2-B4C composites under shock wave loading

A series of plate impact tests were conducted to evaluate the effect of TiB₂ on the mechanical performance of the TiB₂-B₄C composites under ultra-high strain rates. The free surface velocity of sample was monitored by the dual-laser Doppler pin system. The dynamic response and Hugoniot equation of state of the TiB₂-B₄C composites were obtained in shock and impact environments. Experimental results showed that the Hugoniot elastic limit (HEL) of the composites was increased from 14.98 to 16.91 GPa with increasing of loading strain rates. The strain-rate sensitivity of the TiB₂-B₄C composites, as well as the pure TiB₂, was positive. The HEL of the composites was close to that of the matrix material (B₄C), and was little effected by the additional agent (TiB₂ phase) at the strain rates higher than 10⁴ s⁻¹. Compared with previous data, a strong relation was showed between the HEL and the wave impedance of the composites under shock wave loading.     

Study of Jet Interaction with Interlayer Material of Bulging Armor

The paper presents an analytical approach for determining the effects of different properties of inert material of bulging armor sandwich on its efficiency against a shaped charge jet. The crater and shock wave parameters have been investigated. A theoretical relation for calculating the energy of the shock wave, produced by the jet impact, in the inert material has been derived on the basis of continuity of pressure and particle velocity at the interface of jet and inert material. This relation reveals that the higher the velocity of the jet the greater is the amount of energy in the shock wave. The energy of the shock wave also increases with increase of density and decrease of strength of the inert material. The shock energy has been found to further depend on the constants of equation of state of the inert material, (u_s=a+b u).     

Computational simulation of cold spray process assisted by electrostatic force

The integrated model of compressible thermofluid, splat formation and coating formation for the cold spray process has been established. In-flight behavior of nano-micro particles and the interaction between the shock wave and the particles in a supersonic jet flow impinging onto the substrate and further effect of electrostatic force on the particle acceleration are clarified in detail by carrying out a real-time computational simulation. The optimal particle diameters for an impinging particle velocity exceeding critical velocity exist. Particles with the diameter of submicron interact with shock wave and particles are decelerated prior to the impact. However, the particles can be accelerated considerably by utilizing electrostatic forces even in the presence of unavoidable shock waves. Finally, based on the integrated model, the coating thickness in an electrostatic assisted cold spray process is evaluated.     

RDX基铝薄膜炸药与铝粉炸药水下爆炸性能比较

为了减少铝粉炸药在生产过程中因铝粉对环境污染,降低铝粉炸药的撞击感度,提高含铝炸药的成型性及力学性能,将RDX用铝薄膜分层包裹得到新型的铝薄膜混合炸药。将铝薄膜混合炸药与铝粉炸药进行水下爆炸实验与爆速实验,得到两种炸药的爆速与压力时程曲线,经过分析计算得到两种炸药的压力峰值、冲量、冲击波能、气泡脉动周期与气泡能。结果表明：铝薄膜炸药药柱的轴向为RDX与铝薄膜独立贯通的结构,有利于降低混合炸药中添加物对基体炸药爆轰波传播的影响,从而使铝薄膜混合炸药的爆速高于铝粉炸药,导致铝薄膜炸药的冲击波损失系数高于铝粉炸药,使铝薄膜混合炸药的总能量、比气泡能与铝粉炸药相当情况下,其比冲击波能却降低了10.16%～10.33%,计算过程说明铝薄膜混合炸药的C-J压力计算公式具有合理性。