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.     

Shock Profiles Along a Specimen

The observation of shock waves in a block of plexiglass caused by a detonating high explosive charge shows the influence of air-gaps and cover-plates which are attached head on. The shock wave for high explosive charges without any cover plate gives a high maximum pressure which decays quickly. The detonating high explosive charge which is covered with a two millimeter thick disc of copper shows a shock wave which is constant over a certain time. An air-gap between the high explosive charge and the measuring plexiglass block always gives a weak shockwave at the beginning. In the case of an uncovered high explosive charge the expansion of the high explosive products gives a relatively smooth increasing blast or shock wave, and in the case of a covered high explosive charge a strong shock resulting from the following impact of the flying plate.     

Explosive Mixtures Detonating at Low Velocity

Same explosive mixtures detonating at a low velocity and not containing high explosives were experimentally investigated. As a system providing detonation capability, a mixture of ammonium nitrate and powdered aluminium was employed. Glass or urea‐formaldehyde resin beads or lead oxides were used to reduce detonation parameters. Detonation velocity and critical diameter were measured for mixtures differentiated in composition and density. As a result of the investigation, a number of explosives were worked out which are characterized by the capability of stable detonation at a very low velocity (below 1000 m/s) and simultaneously, some of them have a relatively high density (even over 2 g/cm³). An attempt of physical and chemical interpretation of the results obtained is also included.     

Blast Impulse at Very Near Distance

Steel cubes and steel spheres were propelled in radial directions by a detonating cylindrical high explosive charge at scaled distances of 0.05–0.25 m kg^−1/3. The analysed velocities can be simply transferred to momenta, to energies and analysed impulse densities. A little surprising result is that the cubes with the larger area mass achieved remarkably higher velocities compared to the spheres. This is definitely a result caused by different air drag coefficients.     

低能导爆索的试制

介绍了低能导爆索的设计原则、试制过程、结构及性能，认为低能导爆索是一种安全可靠的传爆、起爆器材。     

聚酰胺胺(PAMAM)树形分子用作乳化炸药的稳定剂

用PAMAM树形分子作稳定剂制成了一种新型的乳化炸药,并用高低温循环及室温贮存的电导率测试、扫描电镜等技术对其稳定性作了表征.结果表明,用PAMAM稳定后的乳化炸药具有很好的稳定性,对该乳化炸药的爆速测试结果表明,添加PAMAM后的乳化炸药的爆速反而增加.同时,对此乳化炸药的稳定机理作了初步探讨.     

Hot Surfaces in Heterogeneous Explosives Initiated by a Shock Wave

A model for the macrokinetics of chemical reactions in detonating heterogeneous explosives is proposed based on the assumption that not only point but also surface microcenters (hot surfaces) are formed under the action of an initiating shock wave. The occurrence of surface hotspots can be cause by a local rise in temperature near microcracks and on grain boundaries. The model is tested by measuring pressure profiles during detonation initiation in a TATB based explosive composition.     

石灰石露天矿大块产生原因与爆破技术

对石灰石露天矿山台阶深孔凿岩爆破中大块产生原因进行了分析,并从穿孔参数、炸药单耗、装药结构、微差间隔、起爆方式等方面,提出降低大块率的技术措施,在实践中取得较好的爆破效果.     

The experimental and theoretical study on the spatial-temporal distribution of electromagnetic radiation from JO-8 explosions.

The detonating fuse in the multistage warhead will be subjected to strong electromagnetic interference, derived from electromagnetic radiation generated by explosion of the shaped charge warhead, which may cause premature detonation or misfire. In order to explore the possible electromagnetic environment surrounded the detonating fuse, the spatial-temporal distribution of electromagnetic radiation after the explosion of JO-8 explosive was investigated in this paper. The electromagnetic radiation signal was collected and its frequency coverage was analyzed in the far-field area by the field blast test. Moreover, based on electromagnetic theory, a theoretical model of electromagnetic radiation generated by the explosion of JO-8 explosive was established, and the spatial-temporal distribution of the electric field intensity was illustrated in detail for several typical positions after the explosion. The better agreement between experimental and theoretical results indicates that the proposed theoretical model and computational method are reasonable. On this basis, the distributions of electric field intensity for different positions and various explosive weights were predicted respectively by using distance and explosive weight as variables. This study is expected to provide a reference for the research on the electromagnetic radiation for explosive explosion and anti-explosive electromagnetic interference.     

Blast Effects of High Explosive Charges Detonating in Cylindrical Steel Tubes

Described are tests of cylindrical high explosive charges with an L/D ratio of 2, centrally detonating in steel tubes of different radii and wall thicknesses to measure the bulge respectively the damaging effects of these steel tubes. The results can be described with analytical equations. For a protecting container with minimum weight the radius should be as large as possible, because the necessary tube wall thickness is quadratically decreasing and therefore the weight of the tube is linearly decreasing with increasing tube radius.     

Blast Waves and Fragment Velocities of Erythritol Tetranitrate

Erythritol tetranitrate (ETN) is a highly sensitive nitrate ester that has a similar molecular structure to nitroglycerine and penta‐erythritol tetranitrate (PETN). In this study, experiments detonating 175 g of ETN were repeated three times to measure blast waves 0.6 m above the ground. TNT and PETN were also tested under the same conditions for comparison. The average peak overpressure of ETN was about 30 kPa at 3 m from the explosion center (5.4 m kg^−1/3 scaled distance), which was much higher than that of TNT (about 22 kPa) and similar to PETN. The effects of the reflected wave from the ground appeared at greater distances of 5 and 7 m (8.9 and 12.5 m kg^−1/3, respectively), as verified by the waveforms and high‐speed camera images. Previous TNT data for peak overpressure vs. scaled distance were used to calculate the TNT equivalents for the experimental data, which revealed that ETN had a similar value to PETN. The fragments velocities of steel cylinders were measured, and that of ETN (1040 m s⁻¹) was higher than that of TNT (957 m s⁻¹) and lower than that of PETN (1260 m s⁻¹). The Gurney constant for each explosive was obtained by using the initial fragment velocities.     

SiC Crystals Derived from β-SiC Powder Using a Conically Converging Shock-Wave Technique

α-SiC and β-SiC crystals are prepared from vapor by sublimation of β-SiC powder subjected to a conically converging shock-wave generated by detonating an explosive charge. α-SiC crystals are mainly 6H modifications and their features are plates, pyramids, needles, and filaments grown in the [0001] direction; 4H-SiC filaments are also obtained. α-SiC rods having a triangular cross section develop parallel to the [111] direction.     

通用线形引爆器设计试验

为了弥补药包引爆航空炸弹的不足之处,设计了聚能装药通用线形引爆器,用于引爆现有的各种常规航空炸弹。本文介绍了该引爆器的设计、试验及其结论。     

Initiation Pressure Thresholds from Three Sources

Pressure thresholds are minimum pressures needed to start explosive initiation that ends in detonation. We obtain pressure thresholds from three sources. Run‐to‐detonation times are the poorest source but the fitting of a function gives rough results. Flyer‐induced initiation gives the best results because the initial conditions are the best known. However, very thick flyers are needed to give the lowest, asymptotic pressure thresholds used in modern models and this kind of data is rarely available. Gap test data are in much larger supply but the various test sizes and materials are confusing. We find that explosive pressures are almost the same if the distance in the gap test spacers are in units of donor explosive radius. Calculated half‐width time pulses in the spacers may be used to create a pressure‐time curve similar to that of the flyers. The very‐large Eglin gap tests give asymptotic thresholds comparable to extrapolated flyer results. The three sources are assembled into a much‐expanded set of near‐asymptotic pressure thresholds. These thresholds vary greatly with density: for TATB/LX‐17/PBX 9502, we find values of 4.9 and 8.7 GPa at 1.80 and 1.90 g/cm³, respectively.     

TM型车制乳化炸药的制造及应用

简要叙述了ＴＭ型车制乳化炸药的技术特点,炸药配方,制备工艺,特别是与ＢＣＲＨ－１５型炸药车相匹配的使用效果;此外还介绍了ＴＭ型乳化炸药爆炸技术性能以及在金城钼业公司露天矿爆破实践中取得的良好的爆破效果。     

Impulse Plug Measurements of Blast Reflected Impulse at Close Range

A series of blast tests is described in which blast impulse is measured by an impulse plug technique for spherical explosive charges. In this approach the reflected blast impulse delivered to a hardened bullet‐shaped steel plug is determined from a measurement of the plug terminal momentum. Plug velocity is measured by a high‐speed, high‐resolution video camera operating at 20,000 frames per second. Spherical C4 charges are studied for varying charge weight and charge‐to‐plug standoff distance. Tested standoffs include the demanding near‐field blast zone within which pressure measurement by transducer is extremely difficult or impossible. Results are compared with previous studies made using transducer and impulse plug methods for both C4 and Pentolite charges. The present data for half‐pound C4 charges are in good agreement with much earlier impulse plug data for spherical Pentolite in the near‐field region, however, differences of up to 26 % are noted with more recent transducer measurements for C4 just beyond the near‐field zone. Test results are also compared with hydro‐code simulations of the plug response.     

Effect of the method used to detonate the borehole charges on the breakdown characteristics

Conclusions The change in the method of detonation is an effective means of controlling the energy of the explosion.By choosing an appropriate method of detonating it is possible not only to concentrate the explosive energy in a specified direction but also to increase the total effect of the explosion in various media.Using the bilateral cord detonation it is possible to achieve a 10–40% increase in the work-effectiveness of the charge depending on the type of rock by comparison with detonation from the end; effectiveness can also be increased 17–80% by comparison with detonation along the charge. This will enable the parameters of drilling and explosive work to be changed and make it possible to have a 30% reduction in costs as has been shown in preliminary analysis.Translated from Ogneupory, No. 6, pp. 28–32, June, 1984.     

On the inconsistency of the asymmetric-sandwich gurney formula when used to model thin plate propulsion

The asymmetric sandwich Gurney formula is used extensively worldwide during explosive reactive armor and shaped-charge war-head design, in either its original form^(1,2) or its extended form used to model implosion configurations^(3–5). It is therefore very important to realize that calculations may contradict physical observations when the formula is used to calculate the velocity of thin plates having mass which is smaller than half the explosive mass per unit area. This inconsistency between calculation and experimental results is explained as resulting from the failure of the assumption made in deriving all the Gurney formulas that the velocity distribution of the explosive products is a linear function of the expansion coordinate.     

Slurry explosive detonation synthesis and characterization of 10 nm TiO2

TiO₂ was prepared by detonating a slurry explosive made of Ti precursor, ammonium nitrate, cyclotrimethylenetrinitramine (RDX), and polystyrene (EPS). X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, and UV–vis diffuse reflection spectroscopy revealed that the sample was composed of mixed crystals of rutile and anatase TiO₂ with irregular spherical shapes and 10 nm particle size. The minimum energy gap of the sample was 2.9 eV. An ideal TiO₂ explosive was prepared from a precursor/ammonium nitrate/RDX ratio of 1:1:0.6 and 2 g of EPS as a density modifier.     

Improved Momentum Method

The momentum distribution is modified by using momentum gages of rectangular cross section and of a smaller width to achieve higher angle resolution. The measurement of the impulse density distribution in the elevation direction of a cylindrical high explosive charge with a length to diameter ratio of 1.35 is up to now not presented with higher angular resolution. The impulse densities are changing more than 10 times from the bridge wave to the radial and to the forward axial direction.