Research on Equation of State For Detonation Products of Aluminized Explosive

The secondary reaction of the aluminum powder contained in an aluminized explosive is investigated, from which the energy loss resulted from the quantity reduce of the gaseous products is demonstrated. Moreover, taking the energy loss into account, the existing improved Jones-Wilkins-Lee (JWL) equation of state for detonation products of aluminized explosive is modified. Furthermore, the new modified JWL equation of state is implemented into the dynamic analysis software (DYNA)-2D hydro-code to simulate numerically the metal plate acceleration tests of the Hexogen (RDX)-based aluminized explosives. It is found that the numerical results are in good agreement with previous experimental data. In addition, it is also demonstrated that the reaction rate of explosive before the Chapman-Jouget (CJ) state has little influence on the motion of the metal plate, based on which a simple approach is proposed to simulate numerically the products expansion process after the CJ state.     

Detonation Products EOS by Specifying Gamma (V) for the Principal Isentrope

The standard way of defining an equation of state (EOS) for detonation products is (1) choose a function P_s(V) for the pressure along the principal isentrope, with enough adjustable parameters; (2) integrate it to obtain the internal energy E_s(V); (3) determine the parameters from available data (Chapman Jouget (CJ) state and cylinder expansion test); (4) refer a Gruneisen EOS to this principal isentrope. Using this approach, (1) most of the adjustable parameters have no physical meaning; (2) they are determined simultaneously; and (3) changing one of them requires changing the others.

Instead, we define the principal isentrope by choosing a function for the adiabatic gamma γ_s(V). We show that this has the following advantages over the standard approach: (1) the parameters have physical meaning; (2) they can be determined by a recursive process; (3) the influence of changes in the parameters to cylinder expansion results is obvious.     

炸药震源在济阳坳陷粘土介质中的激发理论初探

针对济阳坳陷的粘土介质,对影响激发效果的因素进行了系统分析和理论探讨。应用爆炸动力学和介质力学等理论,对济阳坳陷粘土介质爆破变形、破坏特征进行了研究;分析了爆炸应力随距离的变化规律;给出了空腔区、破碎区和塑性区的半径计算公式;论证了炸药爆炸能量在粘土介质中的能量分配理论,讨论了炸药爆速、密度等参数以及激发介质的速度、密度、弹性模量对地震波能量的影响。在理论研究的基础上,在济阳坳陷WHZ探区的不同激发介质中进行了13种不同爆速的炸药震源试验,试验结果与理论分析比较吻合,地震资料质量有了改进。     

柴油机气缸套等离子多元共渗研究

用高能等离子束在常压下快速扫描涂敷合金渗剂的柴油机气缸套内表面,可实现多元共渗+自激冷淬火复合硬化,获得的总硬化层深度大于150μm,硬化层显微硬度可达927HV005。对硼铸铁气缸套和等离子多元共渗气缸套进行了磨损对比试验,结果证明,等离子多元共渗气缸套的耐磨性比硼铸铁气缸套高26%,配副活塞环耐磨性提高大约23%,且生产过程稳定,成本低,效率高。     

Microstructure effects on the detonation velocity of a heterogeneous high-explosive

ABSTRACT

Although numerous methods exist for the theoretical calculation of detonation parameters of explosives, few thermodynamic-hydrodynamic-based theoretical codes take into account particle size. The basis for their computational analysis is primarily focused on the equation of state of the detonation products, heat of formation, and density of the explosive composition. This study utilized regression analysis to model the relationship between the microstructure characteristics and detonation velocity of a heterogeneous high-explosive composition containing cyclotrimethylene-trinitrmaine (RDX). The principal characteristics examined were the average particle size of RDX, amount of HMX impurity within the RDX particles, method of RDX manufacture, and compositional density. Statistical analysis demonstrated the relevancy of the microstructure influence on the detonation velocity of the developed experimental compositions of 73 wt. % solids and 27 wt. % polyurethane binder. An equation is developed that accurately predicts detonation velocity based on average particle size, density, and manufacturing process for RDX. The model underscores the significance of the relationship between the average particle size and detonation velocity. Compositions containing smaller average particle sizes of RDX generate higher detonation velocities. A 100 micron increase in the average particle size was shown to decrease detonation velocity by 161 m/s for the monomodal polyurethane compositions used in this study. The relevance of using statistical models for selecting characteristics that result in optimum explosive performance is addressed.     

Modeling Shock Desensitization of Composition B Explosive

The NOBEL multimaterial adaptive grid Eulerian hydrodynamic code was used to model a shaped charge jet formation, its interaction with a steel plate, and shock formation of a bow shock in front of the jet that shocks and desensitizes a cylinder of composition B explosive so that when the jet arrives it fails to initiate detonation. The jet passes through the composition B explosive cylinder, an air gap, and then initiates propagating detonation in a second composition B explosive cylinder that has not been desensitized by a preshock. The experimental arrangement was studied using X-ray radiography at the Material Research Laboratories in Melbourne, Australia.     

Non-Solid Explosives for Shaped Charges. Part II. Target Penetration with Metal Liner Devices Using Sensitized Nitromethane Liquid Explosive

In an attempt to overcome the inconsistencies of plastic explosive–filled shape charges in EOD operations we have explored the use of sensitized gelled nitromethane liquid as a filling for a number of shaped charge devices. The ability to penetrate munition casings and induce deflagration is not only dependent on the velocity of detonation of the mixture, investigated in previous papers, but also on the geometry of the devices used and in some cases the confinement present in the device. In this article a range of nitromethane-based explosive fillings, with a range of velocities of detonation, was used to investigate the performance, in terms of target penetration, of both conical and dished metal liners and flat-bottomed cup liners mounted in cylindrical tubes. A number of unexpected results were obtained when copper dish devices were mounted in metal tubes and demonstrated a penetration dependence on standoff to the target. These observations were confirmed by flash X-ray investigation of the functioning devices. Some discussion of the critical parameters controlling the liner behavior has been undertaken.     

A rapid method for the assessment of the axial output performance of booster charges

Abstract

An experimental method involving the determination of the shock induced in PMMA by a test explosive is described which allows an assessment of the relative output performance of a booster composition in a geometry and size which could be reasonably expected to appear in a weapon design. By applying the same analytical treatment of the experimental results to data generated by the 2-D Eulerian Hydrodynamic Code, HULL, estimates of the detonation pressure and the adiabatic exponent, γ, are obtained. The results indicate that the ordering of performance determined experimentally by this method agrees well with that deduced from velocity of detonation data using a simple γ-law equation of state and with a subsequent experimental verification where the run distance to detonation in a main charge explosive is observed when the booster is separated from the acceptor by a standard attenuator. Further, it is deduced that in the geometry considered using the initiation system described, the booster charges have probably reached steady-state detonation in 25mm lengths.     

Evaluation of the Detonation Performance of Insensitive Explosive Formulations Based on 3,3ʹ Diamino-4,4ʹ-Azoxyfurazan (DAAF) and 3-Nitro-1,2,4-Triazol-5-One (NTO)

Two energetic materials identified for relatively high energy, but little to no response to impact, spark or friction stimuli are 3-nitro-1,2,4-triazole-5-one (NTO), and 3,3? diamino-4,4?-azoxyfurazan (DAAF). More of an outlier in performance versus sensitivity, DAAF illustrates insensitivity by small-scale sensitivity tests, yet has a failure diameter estimated to be 1.25 mm and a short run length to detonation. Because of this unusual behavior, DAAF is an ideal material to formulate with NTO to obtain tailored shock sensitivity and critical diameter, with detonation velocities and pressures higher than PBX 9502. Here, we present detonation properties of Kel-F^® bonded formulations with ratios of 20–70 wt.-% DAAF added to NTO. All formulations were evaluated for detonation velocity, aluminum flyer acceleration at jump-off, and via the cylinder expansion test.     

Thermal Behaviors and Their Correlations of Mg(BH4)2-Contained Explosives

In order to explore the effect of metal hydride on energetic materials’ thermal behaviors and their correlations, we studied the heats of combustion and detonation of RDX, TNT, and Mg(BH₄)₂-containing explosives both theoretically and experimentally. The results showed that Mg(BH₄)₂ can significantly improve the energy of explosive. As the mass fraction of Mg(BH₄)₂ increases, the combustion heat of composite explosives increases gradually, while the combustion efficiency decreases. When its mass fraction is about 30%, the theoretical heats of detonation of RDX/Mg(BH₄)₂ and TNT/Mg(BH₄)₂ reach maximum, which are 7418.47 and 7032.46 kJ/kg, respectively. When we compared the errors between calculation and experimental values, we found that L-C method is more accurate in calculating oxygen-enriched and oxygen-balanced explosives, and that minimum free energy method is more suitable for seriously negative oxygen-balanced explosive. For single explosive, there are three kinds of relationships between heat of combustion and detonation according to the oxygen balance. For Mg(BH₄)₂-containing explosives, the relationship is in accordance with Boltzmann function.     

Effect of RDX powders on detonation characteristics of emulsion explosives

ABSTRACT

To obtain an explosive suitable for the explosive welding of foils and produce a new way to reuse demilitarized explosives, RDX powders and high amounts of hollow glass microballoons (GMs) were introduced into an emulsion matrix to reduce detonation velocity and critical thickness. The effect of different percentages of RDX on the detonation performance of the mixtures was systematically investigated. The results showed that the critical thickness decreased significantly with increasing RDX contents, and the detonation velocity at the critical thickness was almost unchanged for the different RDX contents. Thus, the as-created mixtures were suitable for the explosive welding of foils due to their low detonation velocities and low critical thicknesses. The brisance test results indicated that the brisance of the composite explosives increased with increasing RDX contents, and this trend was more remarkable at low RDX contents. All the energy output parameters of the underwater explosions also increased with increasing RDX contents.     

基于HMX/HNS组合的双层装药射孔弹实验研究

为研究石油射孔弹装药对药型罩爆轰驱动的聚能射流形态和参数,提出一种高性能双层装药射孔弹,通过少量的高爆速辅助炸药改变原主炸药的从起爆端依次传爆的顺序,部分主炸药被几乎同时激发,增大主炸药对药型罩作用的压跨角,提高了原低爆速主炸药的能量利用率。设计3种类型的双层装药射孔弹,由2种炸药组成:一种为爆速高的HMX辅助炸药,一种为爆速较低的HNS主炸药。初步实验验证,装填HMX/HNS炸药的双层装药射孔弹钢靶平均穿深最大提高23.5%,混凝土靶平均穿深最大提高19.6%。基于HMX/HNS组合的双层装药射孔弹模拟计算和实验结果,研究了HMX/RDX组合的双层装药射孔弹在3种类型上的表现,其射流的速度和动能相对于原RDX炸药射孔弹提高较小,实验钢靶、混凝土靶平均穿深最大提高分别只有9.1%、11%。对比HMX/HNS组合与HMX/RDX组合可知,双层装药的射孔弹性能同辅助炸药与主炸药爆速差有重要的关系。     

Remaking and re-using of double based large caliber powders to be used as industrial explosives

Abstract

A possibility of remaking of double based large caliber gun powders of various shapes was verified, using laboratory-scale granulation in double phased liquid system. Loose composition was prepared from obtained granulation product by mixing with ammonium nitrate. This mixture actually corresponds to the simplest industrial explosive. Its efficiency, energetic and detonation parameters were tested and obtained results were comparable with usual range of industrial explosives parameters. Energetic parameters of one mixture are also introduced.     

Formation and structure of axisymmetric steady-state detonation mach stems in condensed explosives

High explosive detonation mach stem phenomena is a relatively new research area which has been studied only since the early 1960's. Although non-steady mach stems in gases have been studied extensively, steady state mach stems have been largely ignored, particularly in high explosives. None the less, steady state detonation mach stems are of great interest due to the observability of continuous highly overdriven detonations. In order to gain a better understanding of axisymmetric steady mach stem formation and structure in high explosives, two dimensional dynamic Lagrangian numerical simulation was done. The results are presented, along with experimental evidence that confirms the validity of the calculations.     

爆轰自增强残余应力的实验测试

以内外径为42mmx95mm的43CrNi2MoVA钢厚壁圆筒为研究对象，实验测试了爆轰自增强处理后所形成的残余应力。首先用Hopkinson拉（压）杆装置测得该材料在高应变速率下的动态力学性能；利用锰铜压力计测得沿移爆轰时界面压力随时间的变化曲线；随后用DYNA3D非线性动力分析程序计算了爆轰载荷作用下圆筒的弹塑性界面半径；最后用Sachs的内层逐次剥层法测量了自增强处理后在器壁上所形成的残余应力。测试结果表明，当超应变度约为70％时内壁面的周向残余压应力可达500MPa，与静液压法自增强在同样超应变度情况下的残余应力（有限元计算值）相差约6％，两种自增强方法在器壁内部的残余应力分布规律有所不同。     

Non-Solid Explosives for Shaped Charges. Part III. Metal Liner Devices Used in Explosive Ordnance Disposal Operations

Disposal of time-expired and unexploded ordnance has proved problematical in the past because of the procedures adopted; i.e., attach an explosive charge and cause the munition to function or long-range projectile attack. Improvements used explosively driven metallic liners to impact on the munition but detonation occurred with the standard plastic explosive fillings. If the munition can be persuaded to burn or at worst deflagrate, then the region of collateral damage could be reduced, even though the extended detonation safety zone would still be required. This article describes some work performed on the initiation of munitions ranging from simulated mortar shells, filled with plastic explosive PE4, via NATO standard 81-mm mortar shells to 1000-lb (450-kg) bombs by either copper cone or dish liners devices filled with various sensitized nitromethane formulations. Most of these formulations initiated deflagrations in the attacked munitions. Detonations resulted in some cases when plastic explosive, PE 4, or chemically (DETA) sensitized NM was used as the device filling. The results were analyzed in terms of the critical rate of energy delivery. Both heat dose and blast overpressure produced by the deflagrations were measured and indicated that the region of collateral damage would be extensively reduced even though the safety exclusion zone, based on full detonation, would have to be maintained. Use of these fillings would reduce the hazard to the operator during EOD work.     

Jet Formation and Penetration Study of Double-Layer Shaped Charge

A theoretical analysis on detonation wave propagation in a double-layer shaped charge (DLSC) is performed. Numerical simulations using the AUTODYN software are carried out to compare the distinctions between jet formations in DLSC and ordinary shaped charge (OSC), in particular, the OSC made using a higher detonation velocity explosive, which is treated as the outer layer charge in the DLSC. The results show that the improved detonation velocity ratio and radial charge percentage of outer-to-inner layer charge are conducive to the formation of a convergent detonation wave, which contributes to enhancement of jet tip velocity in DLSC. The thickness and mass percentages of liner flowing into jet in DLSC closely follow the exponential distribution along the radial direction, but the percentages in DLSC and the mass of effective jet, which have significant influence on the penetration depth, are lower than those in OSC with the outer layer charge. This implies that the total charge energy is the major factor controlling the effective jet formation, which is confirmed by the verification tests using flash X-ray system and following penetration tests. The numerical simulation and test results compare well, while penetration test results indicate that the performance of DLSC is not better than that of OSC with the outer layer charge, due to the differences in jet formation.     

新型耐磨钻井泵缸套试验研究

钻井泵缸套的早期失效主要是耐磨性不足造成的。采用新型耐磨材料与基体材料热膨胀粘合工艺,研制出高抗磨缸套,内层硬度〉70HRC。实验室试验与钻井现场应用结果表明,该缸套的磨损率是国内外高铬高碳双金属缸套的1／25;使用寿命比双金属缸套高50倍。该新型耐磨缸套适用于石油钻井等恶劣工况,能节约钻井成本、提高钻效率。     

Ignition and Growth Modeling of Shock Initiation of Different Particle Size Formulations of PBXC03 Explosive

The change in shock sensitivity of explosives having various explosive grain sizes is discussed. Along with other parameters, explosive grain size is one of the key parameters controlling the macroscopic behavior of shocked pressed explosives. Ignition and growth reactive flow modeling is performed for the shock initiation experiments carried out by using the in situ manganin piezoresistive pressure gauge technique to investigate the influences of the octahydro-1,3,5,7–tetranitro-1,3,5,7-tetrazocine (HMX) particle size on the shock initiation and the subsequent detonation growth process for the three explosive formulations of pressed PBXC03 (87% HMX, 7% 1,3,5-trichloro-2,4,6-trinitrobenzene (TATB), 6% Viton by weight). All of the formulation studied had the same density but different explosive grain sizes. A set of ignition and growth parameters was obtained for all three formulations. Only the coefficient G₁ of the first growth term in the reaction rate equation was varied with the grain size; all other parameters were kept the same for all formulations. It was found that G₁ decreases almost linearly with HMX particle size for PBXC03. However, the equation of state (EOS) for solid explosive had to be adjusted to fit the experimental data. Both experimental and numerical simulation results show that the shock sensitivity of PBXC03 decreases with increasing HMX particle size for the sustained pressure pulses (around 4 GPa) as obtained in the experiment. This result is in accordance with the results reported elsewhere in literature. For future work, a better approach may be to find standard solid Grüneisen EOS and product Jones-Wilkins-Lee (JWL) EOS for each formulation for the best fit to the experimental data.     

自卸货车液压油缸爆裂原因分析

为了探究自卸货车液压油缸在卸货作业过程中突然爆裂的原因,通过宏观观察、扫描电镜分析、光学显微分析和力学性能试验等方法,对液压油缸断裂处母材、焊缝及裂纹扩展区组织及性能进行了试验研究。分析结果表明,液压油缸爆裂起源于油缸表面焊缝,由于焊缝在扩散氢、拘束应力和淬硬组织的共同作用下产生延迟冷裂纹,并在应力作用下,延迟冷裂纹不断扩展,最终导致爆裂失效。建议在缸体焊接时可通过烘干焊接材料及母材、改善焊接工艺等措施来防止爆裂发生。