Impulse Method for the Blast Contour of Cylindrical High Explosive Charges

A simple method for measuring the momentum distribution around a cylindrical high explosive charge is described which has demonstrated high reproducibility. At near distances, around 5 calibers or at scaled distance Z≈0.4 (m/kg^1/3), the radial momentum increases drastically compared to diagonal directions. Surprisingly strong is the difference of the momentum along the axis in the detonation direction, which is 8 to 10 times higher, compared to the rearward direction.     

Detonation Wave Propagation in Double‐layer Cylindrical High Explosive Charges

The flow fields associated with regular and irregular reflections of detonation waves in double‐layer cylindrical (DLC) high explosives (HE) are analyzed, and an analytical model for predicting the detonation wave configurations is proposed. Regular reflection and three‐shock Mach reflection during detonation wave propagation are discussed. Calculated results of pressure, flow velocity, and specific volume are presented and the Mach stem height is also determined based on mass conservation. The corresponding numerical simulation based on the Lee–Tarver model is developed to generate data comparable with an ordinary cylindrical charge. It is shown that steady convergent detonation wave propagation occurs in the DLC charge. The maximum pressure up to 4.0 times of Chapman–Jouguet (CJ) pressure is reached at the collision point related to the Mach reflection, and the predictions based on the proposed model correlate well with corresponding numerical results.     

Predicting the Impulse from the Curved Surface of Detonating Cylindrical Charges

TNT (Trinitrotoluene) equivalency depends on knowing the relative strength of different explosives compared to TNT. However, the current values for TNT equivalency mostly depend on work on spherical charges, whereas most military ammunition is cylindrical in shape. Cylindrical charges are known to give an enhanced blast close in when compared to that of spherical charges. A previous paper looked at predicting the peak pressure perpendicular to the curved side of a cylinder. This paper examines impulse data for the curved surface of cylindrical charges from the literature for Composition B and Pentolite and then describes experimental work carried out on cylindrical PE4 charges. Analysis of the free air experimental and literature data shows that it is possible to predict the impulse using a linear relationship, though it is not possible to decide on the best fit based on the current data. The fits for both I=K_IM^0.5/R and I= M^2/3/R give very similar correlation coefficients, where M is the charge mass and R the distance from the charge and K_I and are constants characteristic of the explosive. Values of K_I and have been fitted to literature and current experimental data for Composition B, Pentolite and PE4. Whichever of these two relationships is used, it should be possible to develop a method of determining TNT equivalency for the curved surface of cylindrical charges by using TNT equivalency=K_{I explosive}/K_{I TNT}, provided that data for TNT cylinders is obtained.     

Predicting the Peak Pressure from the Curved Surface of Detonating Cylindrical Charges

Trinitrotoluene (TNT) equivalency depends on knowing the relative strength of different explosives compared to TNT. However, most past work has been carried out only using spherical charges, whereas most military ammunition is cylindrical in shape. It is known that in certain directions, cylindrical charges give an enhanced blast close in when compared to that of spherical charges. This paper examines data for cylindrical explosive charges from the literature for Composition B and pentolite and then describes experimental work carried out on cylindrical PE4 charges. Analysis of the free air experimental and literature data shows that close into the curved side of a cylindrical charge it is possible to predict the peak pressure using an equation of the form Peak pressure=K×mass/distance³, where K is an explosive dependent constant; 2695 Pa m³ kg⁻¹ for Composition B, 2498 Pa m³ kg⁻¹ for pentolite and 2565 Pa m³ kg⁻¹ for PE4, for length to diameter ratios of between 2 : 1 and 10 : 1. For a scaled distance (distance/mass^1/3) of less than 3.5 m kg^−1/3, the results are very accurate. This means that, provided data for cylindrical charges of TNT is obtained, a simple method of determining the TNT equivalency of a cylindrical charge, perpendicular to the curved surface is given by TNT equivalence=K_explosive/K_TNT. For a more accurate prediction at a scaled distance of greater than 3.5 m kg^−1/3 a cubic equation of the form Peak pressure=K₁Z⁻³+K₂Z⁻²+K₃Z⁻¹ has been found to apply where Z=distance/mass^1/3 and the coefficients K₁, K₂ and K₃ depend on the explosive type.     

Radial Blast Prediction for High Explosive Cylinders initiated at Both Ends

This paper presents experimental results for the double ended initiation of cylindrical, explosive charges. Bare cylindrical charges of PE4 (RDX/binder 88/12 %) were used with length to diameter ratios of 1/3.7 to 5.75/1 and masses of 0.25 to 0.45 kg. Pressure measurements were taken at distances of 1 to 3.5 m in the radial direction. It was found that it was possible to predict the peak overpressure in the radial direction using P=K′ M(L/D)^1/3R⁻³. M is the mass of explosive, L the length of the explosive charge, D the diameter of the explosive charge, and R the distance from the charge. For PE4, K′=2251 kPa m³ kg⁻¹ for all length to diameter ratios. The double ended initiation gives a peak overpressure 1.6 times that for single ended initiation. The impulse for double ended initiation was found to be the same as for single ended initiated charges.     

Analysis of Post Detonation Products of Different Explosive Charges

High explosive charges containing TNT, Comp. B, PBXN-106, TNT/TATB and the aluminium containing charges TNT/AN/Al, Comp. B/Al and a PBX high explosive with polyurethane binder, RDX, AP and Al have been initiated in a containment of 1.5 m³ in argon atmosphere. The gaseous and solid products were analyzed by mass spectrometry and other techniques. From the reaction products, the completeness of the Al reaction under different conditions was evaluated. The heat of detonation was calculated from the heat of formation of the products and the components of the explosive charges. The method described is suitable for studying the reaction behavior of components in composite explosives, especially of less sensitive high explosives.     

Experiments of Initiation of Covered,but Unconfined High Explosive Charges by means of shaped charge jets

Experiments on the initiation of high explosive charges in contact with a barrier or separated from it by a 15 mm air gap or a 2 mm acrylic glass layer have been performed utilising a simultaneous framing and streak camera. With increasing barrier thickness the shaped charge jet is increasingly consumed.     

Critical Criterion for the Shock Initiation/Ignition of Cylindrical Charges with Thin Aluminum Shell Impacted by Steel Fragment

The shock initiation/ignition of Cylindrical Charges Covered with thin Aluminium Shell (CCCAS) by steel fragment impact was experimentally and theoretically investigated. The critical specific kinetic energy criterion and threshold for the shock reaction of CCCAS were obtained. During the experiments, the response characteristics of CCCAS by steel fragment impact were studied. Then the surface microstructures of explosives were examined by scanning electron microscope (SEM). According to the experimental phenomena and existing theories, a calculation model for critical criterion for the shock reaction of CCCAS was developed by dimensional analysis . Based on the calculation model and numerous tests of cylindrical charges covered with 3 mm aluminium shell under the impact of steel fragments with the mass from 1.0 g to 2.0 g, the critical specific kinetic energy threshold for the shock initiation of CCCAS was obtained.     

Study of The Blast Waves from the Explosion of Nonspherical Charges

The blast wave patterns from the explosion of cylindrical charges are very complex and the pressure-time histories exhibit multiple shocks. The accurate assessment of the blast wave parameters (positive peak overpressure, duration, and the positive impulse) thus is not a simple task. In this paper a simple system is described for studying the blast waves from the explosion of small cylindrical charges together with comprehensive methods to analyse the experimental results. The assessment of the near-field/far-field behaviour also has been studied.     

大直径风送管道衬里的技术改造

分析了某公司饲料单元风送管道内部衬里脱落的原因,并提出了将衬里结构改造为耐火砖上涂抹耐火浇注料的改造措施。     

几种不同爆炸冲击波作用的能量谱分析

为得到冲击波能量与目标自振频率之间的关系,利用小波包分析原理对几种不同爆炸冲击波作用进行了能量谱分析,并准确得到各频段的能量值。结果表明,能量谱在某频段的幅值越高,对自振频率在该频段的目标破坏作用就越大。结合各种结构部件的自振频率,分析各种冲击波作用的能量谱,可以选出最适合的药量和爆心距,达到高效毁伤的目的。     

Investigation of Blast Performance and Solid Residues for Layered Thermobaric Charges

The confined explosion of an annular layered charge composed of a phlegmatized RDX (RDXph) core and an external layer consisting of aluminum powder (Al) or a mixture of ammonium perchlorate (AP) and Al was studied. Experiments were carried out in fully and partially closed structures, i.e., in the explosion chamber of 150 dm³ in volume and in the 40 m³ volume bunker with four small holes and a doorway. Two types of aluminum powder were used in the mixtures. Signals of overpressure from two piezoelectric gauges located at the chamber wall were recorded and the influence of aluminum contents and particle size on a quasi‐static pressure (QSP) was studied. Moreover, the solid residues from the chamber were analyzed by using SEM, TG/DTA and XRD techniques to determine their structure and composition. Pressure and light histories recorded in the bunker enable us to determine the blast wave characteristics and time‐duration of light output. The effect of the charge mass and aluminum particle size on blast wave parameters were investigated. For comparison, the test for RDXph and TNT charges were also carried out.     

Agriculture Grade Ammonium Nitrate as the Basic Ingredient of Massive Explosive Charges

Prilled ammonium nitrate (AN) is manufactured globally in millions of tons and is mainly used as fertilizer or as the main ingredient of modern mining blasting explosives. The availability of AN poses a serious threat to public security as it enables preparation of massive explosive charges using a simple technology in order to carry out terrorist attacks. This paper examines the option of using agriculture AN manufactured in several Polish plants as the basic ingredient of explosive mixtures with liquid fuels or powdered aluminum. Fuel oil (FO), 2‐EHN and nitromethane were used as liquid fuels. Additionally, the effect of an inorganic additive (dolomite) in AN on the detonation velocity of mixtures of granulated and milled AN with various fuels was examined.     

岩石膨化硝铵炸药的爆破威力研究

研究了岩石膨化硝铵的爆炸性能和爆破威力，在分析岩石爆破机理的基础上，通过与铵梯炸药，铵梯油炸药的爆破性能比较，并根据其自身的爆速高，重量威力大而体积威力稍小的特点，提出进一步提高该炸药爆破威力的技术途径。     

Generation of Hypervelocity Particle Flows by Explosive Compression of Ceramic Tubes

The compression of ceramic (corundum) tubes by the detonation products of explosives have been studied experimentally and numerically. The formation of the shaped-charge jet of ceramic particles and its effect on steel witnesses targets has been investigated. The tubes were produced by detonation spraying. Ceramic particles were deposited on copper tubes, which were then dissolved in a solution of ferric chloride. In the experiments, a considerable penetration of the flow of ceramic particles was observed. During the interaction of the flow with the target, the target material was partially evaporated, as shown by metallographic analysis. Numerical analysis of the formation of the discrete shaped-charge jet showed that the maximum velocity of the jet head was about 23 km/s, and the velocity of the main part of the jet was about 14 km/s.     

AUTO-DYN模拟炸药爆炸问题的分析

通过CAD/CAE软件建立了不同装药质量与网格尺寸的半无限爆炸场模型,利用AUTO-DYN有限元程序计算出爆炸波的超压值和正压作用时间.将模拟结果与实验数据进行了比较.结果表明,AUTO-DYN有限元程序在模拟爆炸场时,近、中场的计算结果与实验误差相对较大,而远场的计算结果与实验的误差相对较小.计算模型的网格尺寸、计算区域大小和计算机的计算能力对模拟结果有影响.直接使用AUTO-DYN模拟爆炸场对人体的创伤效应存在一定局限性.     

Predicting Blast Waves from the Axial Direction of a Cylindrical Charge

Bare, cylindrical, explosive charges produce secondary shock waves in the direction of least presented area. Whilst the source of these shock waves was explored in the 1940’s, no attempt was made to predict them. This paper describes the detonation of bare, cylindrical charges of PE4 (RDX binder 88/12 %), mass 0.2 to 0.46 kg and with a length to diameter ratio of 4 to 1. High speed camera footage showed (i) the formation of the separate, primary, shock waves from the sides and ends of the charge, (ii) Mach reflection of these separate shock waves, giving rise to reflected, secondary shock waves, and (iii) the secondary shock waves catching and merging with the primary shock wave. In the axial direction, the secondary shock wave’s peak overpressure and impulse exceeded that of the primary shock wave for scaled distances, Z=R/M^1/3 ≥3.9 m kg^−1/3, where M is the mass in kg and R the distance from the charge in m. It was found possible to predict the primary peak overpressure, P, at all distances in the axial direction, for a constant length to diameter ratio, using P=3075 Z⁻³−1732 Z⁻²+305 Z⁻¹. Close in the primary peak overpressure is proportional to M/R³ in the axial direction. It was not possible to predict the secondary peak overpressure with the data obtained. The total impulse from both shock waves, I, in the axial direction can be predicted using I=746(M^2/3/R)³−708(M^2/3/R)²+306(M^2/3/R).     

钢管用新型耐烧蚀涂层研究

介绍了一种钢管用新型耐烧蚀涂层的研究情况。在对涂层材料基本性能研究的基础上,采用带有涂层的 钢管和无涂层钢管的对比实验对所研制涂层材料的实用性进行了研究。实验结果表明:涂层材料的拉伸强度达到 7 MPa;伸长率为1．04％;附着力为2．25 kg/cm2;导热系数为0．334 W/(m·K);比热容为4．669×103J/(kg·K);密 度为0．83 g/cm3;氧-乙炔烧蚀的线烧蚀率为:0．204 mm/s,质量烧蚀率为:0．0873 g/s;热分解温度在330-600℃;涂 层使钢管的熔速大幅度下降。     

Acceleration and Viscoplastic Deformation of Spherical and Cylindrical Casings under Explosive Loading

A theoretical model to predict continuous deformation and acceleration of spherical or cylindrical metallic casings driven by detonation products inwards or outwards before fracture occurring is proposed in this paper. The casing materials are assumed to be rigid viscoplastic medium and the geometries are one dimension i.e., the explosive charge is initiated at the spherical center or on the cylindrical axis in the divergent case, or uniformly on the explosive shell's outer surface in the convergent case. The acceleration movements of spherical and cylindrical casings calculated with this model are in good agreement with experimental and numerical results performed with the finite element hydrocode DYNA2D. It is concluded that this model describes well one‐dimensional divergent and convergent movements of spherical or cylindrical casings under explosive loading, and provides a useful method to explore related problems, such as shell's fragmentation, its maximum velocity before fracture, blast wave in the near area adjacent to the casing and solid liner implosion.