Interactions of Impact Shock Waves in a Thin-Walled Explosive Container. I. Impact by a Flat-Ended Projectile

Interaction of impact shock waves that could detonate an explosive (Composition B) confined in a thin-walled container impacted by a cylindrical projectile is numerically studied, based on the Forest Fire explosive reaction rate model. After the impact, rarefaction waves from projectile periphery and front cover–explosive interface catch up the forward-moving shock fronts in the explosive as well as in the projectile. At a high impact velocity, the transmitted shock front induces detonation at the front cover–explosive interface. At an intermediate velocity, the rate of energy release from the shock-compressed volume in the explosive is such that the associated effects prevail over the effects caused by rarefaction waves, leading to detonation after the shock wave travels a certain distance in the explosive. There is a range of minimum impact velocities at which the effect of rarefaction waves prevails over the energy release; hence, the detonation is excited not behind the shock-wave front moving over the explosive but only after shock-wave reflection from the high-impedance back plate. It is suggested that, in interpreting the detonation behavior of an explosive confined by a high-impedance container, one should take into account the effects of shock-wave interaction with container walls.     

新型高能钝感炸药JBO-9X在较高冲击压力下冲击起爆过程的实验研究

采用高速扫描相机和楔形炸药构型,对新型高能钝感炸药JBO-9X的冲击起爆过程进行了实验研究;采用LS-DYNA软件对实验结果进行了数值模拟验证。结果表明,在6.9GPa的入射冲击压力下,JBO-9X炸药的冲击转爆轰时间为1.5μs,冲击到爆轰的距离为7.9mm;当冲击波刚进入炸药时,炸药发生化学反应的比例(λ)为0.2,随着冲击波进入炸药的距离增加,受试炸药中发生化学反应的比例逐步增加。在实验条件下,入射冲击波压力为6.85GPa时,JBO-9X炸药的冲击到爆轰距离为8.0mm。化学反应比例随冲击波进入炸药距离的增长曲线与实验基本相同。     

FOX-7和RDX基含铝炸药的冲击起爆特性

为研究FOX-7和RDX基含铝炸药的冲击起爆特性,对其进行了冲击波感度试验和冲击起爆试验,结合冲击波在铝隔板中的衰减特性,确定了FOX-7和RDX基含铝炸药的临界隔板值和临界起爆压力,并通过锰铜压阻传感器记录了起爆至稳定爆轰过程压力历程的变化。结果表明,以Φ40mm×50mm的JH-14为主发装药时,FOX-7和RDX基含铝炸药临界隔板值分别为37.51和34.51mm,对应的临界起爆压力为10.91和11.94GPa;起爆压力为11.58GPa时,FOX-7炸药的到爆轰距离为25.49~30.46mm,稳定爆轰后的爆轰压力为27.68GPa,爆轰速度为8 063m/s;起爆压力为14.18GPa时,RDX基含铝炸药的到爆轰距离为17.27~23.53mm,稳定爆轰后的爆轰压力为17.16GPa,爆轰速度为6 261m/s。     

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。     

A Numerical Study of Explosive Heating due to Projectile Impact

A finite difference Eulerian computer code with some very useful Lagrangian features is employed to study the impact of a projectile on a heavily confined, inert, solid explosive. Temperature rise due to shock compression and plastic deformation in both the explosive and the metal confinement is estimated. It is concluded that in situations where the shock is weak and the explosive does not initiate shortly after the projectile impact, the possibility of it so doing, due to plastic deformation, at a later time cannot be discounted.     

用电磁粒子速度计实验研究一种TATB基钝感炸药的冲击响应

针对一种新的TATB基钝感炸药(Tx),应用组合式电磁粒子速度计(EMV)测试技术,测量了炸药直接加载、增加有机玻璃隔板以及炸药驱动飞片3种加载状态下炸药内部的粒子速度历程和冲击波轨迹。根据测试结果,分析了不同加载压力下炸药的冲击响应过程。结果表明,炸药直接加载时,加载压力最高,Tx钝感炸药很快达到爆轰状态,到爆轰距离约为1.5mm;在增加有机玻璃隔板、加载压力为14.2GPa时,与直接加载时炸药粒子速度一致,Tx钝感炸药的到爆轰距离明显增加,约为5mm;在炸药驱动飞片、加载压力为9.5GPa时,Tx钝感炸药的粒子速度逐渐降低,存在一定钝化现象,到爆轰距离达到20mm以上。     

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.     

反应装甲冲击引爆试验研究

研究了HMX基钝感炸药的机械感度.根据测试结果初步确定了反应装甲的装药配方,最终装药配方由改变模拟反应装甲上、下板的材料和厚度以及穿甲弹与反应装甲法线的夹角,用反应起始装药的引爆效果确定.结果表明,钝感炸药的撞击感度、摩擦感度均随HMX粒度的减小而降低,随钝感剂含量的增加而降低;反应装甲的装药配方为HMX97%、钝感剂3%.从理论上分析了炸药粒度变化对机械感度影响的机理,以及在穿甲弹参数和速度一定的条件下,反应装甲装药结构对冲击引爆的影响.     

Radiographic study of interaction of shock and detonation waves in a high explosive

Collisions of shock and detonation waves in an HMX-based high explosive are experimentally studied with the use of flash radiography. Based on X-ray patterns, specific features of the wave-interaction process are identified, and qualitative differences are found in detonation formation and evolution in an explosive precompressed by a weak shock wave and in an undisturbed explosive. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 3, pp. 132–138, May–June, 2007.     

加氢裂化循环气支链爆炸形态的区划与应用

对加氢裂化循环气与相关可燃性气体支链爆炸的特性及其应用进行了系统的研究.探索了浓度爆炸极限、爆炸形态与波形及其影响因素;根据爆炸形态与波形的不同,提出了对加氢裂化循环气爆炸形态科学区划的新理念;在爆炸极限内,可以进一步区划4种爆炸形态(冷焰、爆燃、爆轰、爆燃向爆轰转化),与7个爆炸区域（上、下冷焰区,上、下爆燃区,上、下爆燃向爆轰转化区,爆轰区）,并探讨了不同爆炸形态压力波的发展机制.对进一步研究相关的多元支链爆炸体系,促进多元支链爆炸理论的发展,具有一定的理论价值.实验测得了爆炸危险度、火焰蔓延极限、最小点火能等特性参数;引进了“关键组分”的概念,指出加氢裂化循环气的多元体系,引发爆炸的物质是关键组分H₂和氧化剂O₂;探讨了制订防爆安全指标的依据与方法.对于预防混合气体支链爆炸事故的发生、指导防爆电气设备与阻火器的设计、指导支链燃烧与支链爆炸的实践,具有参考价值.     

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.     

Initiation of explosive processes in hydrogen-containing gas mixtures by a multijet flow of detonation products

Explosive regimes initiated by interaction of a detonation wave with a permeable screen are studied experimentally. Possible explosive regimes that may form behind the screen are found to be detonation, deflagration-to-detonation transition, quasisteady system consisting of the shock wave and the flame front, and decaying shock wave with the flame lagging behind it. The effect of the mixture sensitivity and screen parameters on the possibility of realization of a particular explosive regime is determined; the dynamics of the explosive regimes near the screen is considered. It is demonstrated that the interaction of the system consisting of the shock wave and the flame front with the screen can lead to initiation of detonation behind the screen.     

复合油相材料对低温快速化学敏化乳化炸药的影响

采用正交试验法研究复合油相材料性能指标对低温快速化学敏化乳化炸药爆轰性能及储存期的影响,并探寻适合低温快速化学敏化乳化炸药生产且满足其储存期要求的复合油相材料指标。     

Effect of Al/O Ratio on the Detonation Performance and Underwater Explosion of HMX‐based Aluminized Explosives

The performance of detonation and underwater explosion (UNDEX) of a six‐formula HMX‐based aluminized explosive was examined by detonation and UNDEX experiments. The detonation pressures, detonation velocities, and detonation heat of HMX‐based aluminized explosive were measured. The reliability between the experimental results and those calculated by an empirical formula and the KHT code was verfied. UNDEX experiments were carried out on the propagation of a shock wave and a bubble pulse of a 1 kg cylindrical HMX‐based aluminized explosive underwater at a depth of 4.7 m. Based on the experimental results of the shock wave, the coefficients of similarity law equation for the peak pressure and attenuation time constant of shock wave were in acceptable agreement. The bubble motion during UNDEX was simulated using MSC.DYTRAN software, and the radius time curves of bubbles were determined. The effect of the aluminum/oxygen ratio on the performance of the detonation and UNDEX for an HMX‐based aluminized explosive was discussed.     

模拟破片撞击下PBX-2炸药的响应规律

为了研究炸药在不同速度破片撞击环境下的安全性能,设计了小弹丸撞击方式模拟破片作用,对PBX-2炸药进行了撞击试验。采用锰铜压力计测试样品中的压力变化,通过高速录像照片分析了点火反应过程,用冲击波超压传感器测量了炸药的反应超压,获得不同速度模拟破片撞击下炸药的响应规律。结果表明,模拟破片试验中PBX-2炸药反应程度明显高于枪击试验;建立的模拟破片撞击试验方法为评估炸药在异常环境下的安全性能提供了一种新的技术途径。     

Mach Wave Control in Explosively Formed Projectile Warhead

A Mach wave emerges at the top of the liner when a wave shaper is embedded in charge, and thus seriously breaks the explosively formed projectile (EFP) nose. Thus, to avoid breakage at the EFP nose, the pressure behind the Mach wave should be controlled. An analytical model for calculating Mach wave parameters is presented based on three‐shock theory. The parameters of Mach waves, such as their growth angles and radii, their velocity along the plane of symmetry, and the pressure behind them, can be determined. Calculation results show that when the diameter of the wave shaper is reduced or the distance between the wave shaper and liner increases, the incident angle of the detonation wave at the top of the liner increases and thereby lowers the pressure behind the Mach wave. Avoiding the occurrence of Mach waves by reducing the incident angle fails to avoid breakage at the nose of the EFP, but lowering the pressure behind the Mach wave by increasing the incident angle avoids breakage at the nose of the EFP. Calculation and simulation results are validated through X‐ray imaging experimentation.     

The formation of smooth spalls in steel during the interaction of glancing detonation waves

A study is made of the formation of smooth spalls in steel specimens when their surfaces are blasted by explosive charges via a glancing detonation wave. When a steel specimen is blasted with an explosive, behind the front of glancing shock waves of compression two glancing shock waves of rarefaction, propagating toward each other, form, the interaction of which produces in the steel a smooth spall in the form of a dihedral angle. It is shown that a variation of the composition of the explosive (TNT, plastic explosive, TG 50/50 alloy) of a given thickness changes the distance from the vertex of the dihedral angle to the surface at which the charge was placed.VNIIÉF, Arzamas-16 607200. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 4, pp. 138–140, July–August, 1994.     

加热前后PBX-2炸药的撞击响应

为了研究炸药在加热前后撞击安全性能的变化,设计了热与撞击复合加载试验系统,并对Φ50 mm×50 mmPBX-2药柱进行了试验.试验中采用热电偶测量药柱不同位置温度的变化过程,通过高速摄像照片记录了点火反应过程,用冲击波超压传感器测量了炸药的反应超压,初步获得了加热前后PBX-2炸药的撞击响应特性.结果表明,加热后的P...     

Initiation of detonation in explosives on an U-70 proton accelerator

Detonation initiation in a composite explosive based on HMX and TATB loaded by a divergent shock wave was studied on a U-70 proton accelerator using proton radiography. Density distributions behind the initiating shock front at various times were obtained. Detonation failure due to collision of shock and detonation waves was studied for a plastic-bonded TATB sample using radiography. Characteristic features of the explosive transformation under shock-wave loading were determined from the images obtained.     

Detonation propagation in thin explosive layers with inert partitions

This paper describes the experimental results in the study of detonation transfer in thin layers of a PVV-12M plastic-bonded explosive (90% of RDX and 10% of bond) through solid and perforated partitions. The critical thicknesses of steel or Plexiglas partitions, exceeding which makes detonation transfer impossible, are determined for the explosive layers with a thickness of 2–12 mm. It is shown that shock waves in the plates, which bound the explosive charge, can stay ahead of the initiating shock wave in the passive part of the explosive charge and load the explosive charge from the lateral surface. Thus, the peripheral desensitized layers of the explosives are formed, which reduce the layer thickness of the detonable explosive and complicate the detonation transfer. Detonation transfer through the partitions whose thickness is greater than the critical thickness can be carried out with the use of holes in the partition, closed by thin plates. The plate thicknesses at which detonation propagates through the hole either in forward and reverse directions or in the forward direction only, are determined.