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Since the nowadays used lead-based primary explosives, lead azide, picrate and styphnate suffer from various environmental and toxic issues, there is a great need for new green materials. Therefore, two highly promising lead-free primary explosives potassium 1-(N-nitramino)-5H-tetrazolate (1, 1-KNAT) and potassium 2-(N-nitramino)-5H-tetrazolate (2, 2-KNAT) have been synthesized and characterized. Both isomers show superior energetic performance, initiation capability and were comprehensively analyzed by low-temperature X-ray diffraction, IR, multinuclear NMR spectroscopy, elemental analysis, and DTA. Sensitivity determinations toward impact, friction, and electrostatic discharge revealed its highly powerful, but also sensitive character. In addition, their potential as lead-free primaries were evaluated in initiation tests of PETN or RDX filled detonators confirming their great suitability as lead-free primary explosives.

Synthesizing energetic metal-organic frameworks at ambient temperature and pressure has been always a challenge in the research area of energetic materials. In this work, through in situ controllable synthesis, energetic metal-organic framework gem-dinitromethyl-substituted dipotassium 4,5-bis(dinitromethyl)-1,2,3-triazole with a "cage-like" crystal packing was obtained and characterized. Most importantly, for the first time, we found that it could be successfully afforded with a catalytic effect of trifluoroacetic acid. This new compound exhibited its high density (2.04 g cm-3 ) at ambient temperature, superior detonation velocity (8715 m s-1 ) to that of lead azide (5877 m s-1 ) and comparable to that of RDX (8748 m s-1 ). Its detonation products are mainly N2 (48.1 %), suggesting it is also a green energetic material. The above-mentioned performance indicates its potential applications in detonator devices as lead-free primary explosive.

Experiments were conducted to study the underwater explosion performance of emulsion explosives (EE) after hot water bath. Spherical charges of EE with different sensitizers and hot water bath were prepared and tested. As for as-prepared charges, the detonation velocity experiments and underwater explosion experiments were carried out and the crystallization ratio was measured and calculated by the dissolution and neutralization method. The results showed an inverse relationship between explosion parameters (pressure peak, specific impulse, detonation velocity and specific total energy) and heating time. It also revealed that the effective explosive weight of EE was reduced with long time of hot water bath. Moreover, the crystallization ratio and the decreasing rate of explosion parameters of EE sensitized by NaNO2 were apparently higher than EE containing physical sensitizers (glass microballoon and perlite), which was attributed to the different destruction mechanism of EE. After 6-hour hot water bath, the EE containing physical sensitizers still retained detonator sensitivity and more than 80 % of specific total energy. Meanwhile, the crystallization ratio was less than 20 %. Whereas, the EE sensitized by NaNO2 lost the detonator sensitivity and the crystallization ratio of EE was also above 40 %.

The burning rates of a slow reacting Mn+Sb2O3 and a fast reacting Si+Pb3O4 time delay composition, filled into lead tubes, were measured with an infrared camera, with two thermocouples and in the form of a fully assembled detonator. The infrared camera method returned values that were on average about 12 % lower than those recorded for the detonators. The temperature profiles measured for the slow burning elements were fully developed, whereas those obtained for the fast burning Si+Pb3O4 elements were not. A numerical model was developed to simulate the Mn+Sb2O3 system. Kinetic parameters were determined by least square fits to the recorded surface temperature profiles. The model made it possible to determine the effect of various property variations on the burning rate. The thermal conductivity of the delay composition was found to have the smallest impact and the heat of reaction the largest effect.

A miniature rocket device integrating nanothermite and RDX is presented for shock initiation of high explosive application. This O 2.5 mm device consists in several assembled and screwed parts: a pyroMEMS chip with a Al/CuO multilayers on it to ignite within less than 100 μs a few milligrams of nanothermite, which reacts violently and ignites within 150 μs a RDX charge compacted in the closed combustion chamber. The gases generated by the RDX combustion rapidly expand, cut and propel a O 2.5 mm by 1 mm thick stainless steel flyer in the barrel. After the presentation of the rocket design, fabrication and assembly, by measuring the pressure-time evolution in the chamber we demonstrate the advantage to ignite the RDX with Al/Bi2O3 nanothermite to optimize the pressure impulse. We show that the stainless steel flyer of 40 mg is properly cut and propelled at velocities calculated from 665 to 1083 m s−1 as a function of the RDX extent of compaction and ignition charge. As expected, the average flyer velocity increases with the mass of loaded RDX and flyer's shear thickness. We finally prove that the impact of the flyer can initiate directly in detonation a RDX explosive, which is very promising to remove primary explosives in detonator.

The entry into force of the REACH regulation implies a modification of the low-cost detonators manufacturing by finding new substances to replace common primary explosives that contain restricted chemicals. Herein, an alternative solution with a two-stage electric detonator that contains only secondary high explosive is proposed. It is based on a two steps process, first a combustion, then a shock to detonation transition. This initiator shows high safety level and is compliant with the STANAGs and the REACH regulation. Contrarily to the EBW detonators, it can be initiated using low voltage and low current. Power supply system can be therefore very compact that is of great advantage for designing pyrotechnical train that have to be integrated into small pyrotechnical mechanisms.

A comprehensive investigation to determine the initiation power of detonators containing as a base charge the novel explosives: dihydroxylammonium 5,5-bis(tetrazolate-1N-oxide) - TKX-50, dihydroxylammonium 5,5-bis(3-nitro-1,2,4-triazolate-1N-oxide) - MAD-X1, pentaerythritol tetranitrocarbamate - PETNC and 3,3-diamino-4,4-azoxyfurazan - DAAF in comparison with RDX, HMX and PETN was undertaken. In order to estimate the initiation power of the detonators, the underwater initiating capability test was used. The total energy as a sum of the primary shock wave energy and the bubble gas energy was determined for each of these explosives, by measuring the overpressure of the shock waves generated in water. Moreover, the complete synthesis for novel explosives is presented. The thermal behavior of the explosives was investigated using DSC (differential scanning calorimetry). The gas phase absolute molar enthalpies at 298K and 10(5)Pa were calculated theoretically using the modified complete basis set method (CBS-4M;M referring to the use of minimal population localization) with the Gaussian 09 software. Gas phase standard molar enthalpies of formation (H-f degrees((g))) at 298K were computed using the atomization energy method. Standard molar enthalpies of formation (H-(s)degrees) were calculated using H-f degrees((g)) and the standard molar enthalpies of sublimation by applying Trouton's rule. The Chapman-Jouguet (CJ) characteristics based on calculated H-(s)degrees values were computed using the EXPLO5 V6.01 thermochemical computer code. For the calculations the theoretical maximum densities and densities obtained during the experiments presented in this work were used.

Dynamic wave interaction and crack propagation in glass have been observed with the edge-on impact (EOI) style test method using an exploding bridged wire (EBW) detonator. The existence of an interlayer or internal surface displayed meaningful wave distortions, delays, reflections, and decreasing amplitude. The interlayer materials used were rubber, stainless steel, and cut surface. The results indicate that the shocks passing the interlayer decrease following the impedance condition and that much of the crack is stopped at the interlayer. The damage pattern was analyzed with the energy and stress dissipation rate.

To ensure good performance of high explosive devices over long periods of time, initiating powders need to maintain their specific surface area within allowed margins during the entire duration of deployment. A common diagnostic used in this context is the Fisher sub-sieve surface area (FSSA). Furthermore, commercial permeametry instruments measuring the FSSA requires the utilization of a sample mass equal to the crystal density of the sample material, an amount that is often one or two orders of magnitude larger than the typical masses found in standard detonator applications. Here we develop a customization of the standard device that can utilize just tens of milligram samples, and with simple calibration yield FSSA values at ac curacy levels comparable to the standard apparatus. This necessitated a newly designed sample holder, made from a material of low coefficient of thermal expansion, which is conveniently transferred between an aging chamber and a re-designed permeametry tube. This improves the fidelity of accelerated aging studies by allowing measurement on the same physical sample at various time - instants during the aging process, and by obviating the need for a potentially FSSA-altering powder re-compaction step. We used the customized apparatus to monitor the FSSA evolution ofmore » a number of undoped and homolog-doped PETN powder samples that were subjected to artificial aging for several months at elevated temperatures. These results, in conjunction with an Arrhenius-based aging model were used to assess powder-coarsening - rates under long-term storage.« less

A new primary explosive, the silver salt of 4,6-diazido-N-nitro-1,3,5-triazine-2-amine (AgDANT), was synthesized and characterized. AgDANT was prepared with a 97 % yield and characterized by IR spectroscopy, single-crystal X-ray diffraction, and DTA. The crystal density of AgDANT is 2.530 g cm−3 and the molecule consists of a centro-symmetric dimer with a high degree of planarity. The intramolecular AgAg distance is relatively low (331 pm) and can be considered as a strong argentophilic interaction. AgDANT is non-hygroscopic and its solubility in water (1.27 mg in 100 mL at 23 °C) is on a similar level of solubility to that of silver azide. The sensitivity of AgDANT to impact is slightly higher than that for MF, sensitivity to friction is the same as for LA, and sensitivity to electric discharge is between that for LS and MF. Initiation efficiency of AgDANT was tested in electric detonators and compared to dextrinated lead azide (initiation efficiency of AgDANT is 40 mg for PETN secondary charge). The thermal resistance of detonators with AgDANT is satisfactory; all detonators were fully functional after exposure at 65 °C (30 d) and 85 °C (2 d).

The purpose of this study is to design a high-shock acceleration apparatus that can be used in a laboratory, alleviating the need for expensive and complex experiments. The key components of this device include a detonator, dynamite, a shock transmission bar, the housing for the test object, and an accelerometer. The device uses the detonation of the dynamite to generate instantaneous accelerations of up to 105 m s−2, which last for hundreds of microseconds. The acceleration forces over the most significant frequency range of the system were analyzed using the shock response spectrum (SRS) method. The device output provides a test sample of 1 kg with the high-acceleration shock condition required by the Mil-Std-810F shock test specification.

A complete study of an exploding bridgewire detonator (EBW), an LX-07 hemispherical booster and a PBX 9502 outer shell are described. Breakout times from all three are listed in terms of first impact on the booster, i.e., code times. Lucite windows are also used to obtain particle velocities at the edges of each explosive, and these are converted into explosive pressures. The key to modeling is the use of the profile of the aluminum detonator can as it impacts the booster, i.e., we need to know the curvature of the end of the booster can. Modeling even with coarse zoning shows that (i) using reactive flow in the booster is better than programmed burn, (ii) creating the flyer curvature helps, and (iii) creating the time differences of flyer impact helps even more.

As well as improving the survivability of weapons and platforms, insensitive munitions (IM) reduce both casualty rates and mission losses. Their use also leads to improved safety during storage and transportation. For a munition to fulfil IM criteria, each of its energetic sub-sections must be IM compliant. The initiator and explosive train are the most critical of these subsystems as their safety and reliability are of paramount importance if the weapon is to be suitable for service use, yet they are generally the most difficult part of a weapon to protect from inadvertent initiation. As part of an ongoing study into initiation methods suitable for use in IM systems, an investigation into the behaviour of energetic materials when impacted by laser-driven flyers was performed. Laser-based detonators exhibit increased safety characteristics over conventional initiation methods as they can be based on insensitive secondary explosives rather than sensitive primary explosives. Also, they are less susceptible to accidental initiation due to an external hazard threat. Single pulses from a high-powered Q-switched Nd:YAG laser were used to launch flyers from substrate-backed aluminium films to velocities up to 6 km s 1 across a short stand-off to impact explosive targets. Several novel energetic materials have been selected for investigation as potential candidates for inclusion within flyer-based initiation systems and explosive train applications. The materials are of interest due to their increased thermal stability and power output over conventional explosives currently in service. Attempts were made to increase the flyer responsiveness of the materials by tuning their particle size using ultrasound. The effect of particle size on the initiation threshold energy was investigated for three materials.

Lead and its compounds in detonator time delays are being phased out owing to environmental and health concerns. It was found that changing from the conventional rolled lead elements to rigid aluminium tubes caused a significant decrease in the burn rate. It also impaired ignitability, especially of slow burning compositions such as SiBaSO4. Consequently, potential alternatives for the latter and also the fast burning SiPb3O4 system were sought. Bi2O3, prepared by thermal decomposition of bismuth subcarbonate, gave fast burning compositions with silicon as fuel (155 mm s−1 with 20% Si). This system was ignitable by the spit of a shock tube. The SiSb6O13 system required an initiating composition and yielded slow burning compositions. The lowest sustainable and reproducible burn rate in lead tubes, in the absence of additives, was 4.8 mm s−1. In lead tubes, it was possible to reduce the burn rate further by adding fumed silica: A composition obtained by adding 10% fumed silica (add-on basis) to a 10% Si–90% Sb6O13 composition still burned reliably at a burn rate of 2.3 mm s−1.

Direct still photography and flash silhouettes have been used to obtain information on the factors governing the incidence of methane/air ignitions caused by instantaneous and short-delay electric detonators. The probability of an instantaneous detonator causing ignitions appears to be a function of the nature and size of the explosive charge and the density to which it is pressed. The incendivity of the short-delay series, on the other hand, appears to be governed by the type of delay element used, and whether that element has a slag ejection confined within certain limits of ejection velocity and projected distance. A non-incendive short-delay detonator has also been investigated.

A comparative study of the properties of gunshot residue (GSR) collected from shooter's hands and from inside the case of the same cartridge used in a shooting experiment was performed. Three types of popular Luger 9 mm ammunition were chosen with primer mixtures based on different types of detonators: mercury fulminate, lead styphnate or lead azide and an organic one, e.g. diazodinitrophenol. Two modifications of lead-free ammunition, with copper and tin plated projectiles were used. Samples of GSR were examined by means of scanning electron microscopy and energy dispersive X-ray spectrometry. Both, similarities and differences in the chemical composition and morphology of GSR secured from the hands of the shooting person and from the appropriate cartridge case were observed. The chemical composition of the characteristic gunshot particles originating from the primer may be influenced by the chemical composition of other parts of the cartridge case, especially the core and the jacket of the projectile. Thus, the distribution of the chemical elements in GSR strongly depends on the direction of the reaction path starting in the primer cup placed at the bottom of the cartridge case, moving along the cartridge case and finishing when the projectile leaves the gun muzzle. A reliable comparison of the airborne residue to these taken from cartridge case for forensic purposes requires some experience based on laboratory experiments performed under controlled conditions. Copyright © 2007 John Wiley & Sons, Ltd.

A screening test was developed at Los Alamos National Laboratory [1] that can be used to decide if a newly synthesized/formulated explosive might warrant further development. The test consists of firing a rate-stick composed of 12.7 mm diameter by 12.7 mm high pellets of different densities ordered from lowest to highest, initiated by a detonator at the low-density end of the stick. This poly-rho test yields detonation velocities over a range of densities using only the small amount of the explosive typically generated by the synthetic organic chemist at an early stage of the scale-up process. The amount of material required is far less than that required for the typical rate-stick series. This paper presents results on poly-rho tests that were conducted on three explosives commonly used at Los Alamos National Laboratory, namely PBX 9501, PBX 9502 and PETN. The results are compared with empirical detonation-theory predictions and existing explosive experimental data, with good agreement in all cases.

Streak camera breakout and Fabry-Perot interferometer data have been taken on the outer surface of 1.80 g/cm3 TATB hemispherical boosters initiated by slapper detonators at three temperatures. The slapper causes breakout to occur at 54° at ambient temperatures and 42° at −54 °C, where the axis of rotation is 0°. The Fabry velocities may be associated with pressures, and these decrease for large timing delays in breakout seen at the colder temperatures. At room temperature, the Fabry pressures appear constant at all angles. Both fresh and decade-old explosive are tested and no difference is seen. The problem has been modeled with reactive flow. Adjustment of the JWL for temperature makes little difference, but cooling to −54 °C decreases the rate constant by 1/6th. The problem was run both at constant density and with density differences using two different codes. The ambient code results show that a density difference is probably present, but it cannot be quantified.

Aiming to solve the problems caused by primary explosives in traditional detonators, a new kind of non-primary explosive detonator based on the principle of flying plate detonator is invented. However, in some special circumstances, such as high temperature, strong radiation, strong magnetic field, overload, high-pressure conditions, the non-primary explosive detonator cannot work well because of the defects of its usual used initiating method like electric hot wire initiating devices, electric exploding bridge wire initiator, and initiating by a shock-conducting tube. In this context, initiation by low energy laser is applied to non-primary explosive detonator. After this combination, the non-primary explosive detonator performs well in resisting high temperature, high pressure, overload, and electric interference.

NHN is a thermally and hydrolytically stable solid, easily prepared from available raw materials. Its preparation liquor can be used repeatedly, which means no waste-water pollution in industrial manufacture. NHN is not sensitive to impact, friction, or electrostatic charge, but is more sensitive to flame. It is demonstrated that NHN is suitable as a replacement for lead azide as an intermediate charge in commercial detonators.

Generally speaking, today's small-calibre munitions, filled with conventional melt-cast or pressed high explosives, are classified in the 1.1 or 1.2 Hazard Divisions because they explode when exposed to various threats, such as fuel fire and sympathetic detonation. The RDX-based B2238 composition is a low-cost and less sensitive cast PBX originally developed by SNPE for the initiation of cast PBX main charges. While it is easily initiated with conventional detonators, B2238 offers the same degree of insensitivity as other cast PBXs used for main charges (HEXABU 88A or OCTORANE 86B for example) and does not explode when exposed to fire and/or bullet impact. Feasibility tests carried out on several types of small-calibre munitions have shown B2238 explosive filling to be an excellent solution in the design of small calibre insensitive munitions with a high performance (in terms of fragments and shaped charge jet) comparable to that of the most energetic conventional high explosives such as 98RDX/2wax. As a result, the new IM standards, currently being defined, should allow in the future to reclassify the small-calibre munitions filled with B2238 in Hazard Divisions other than 1.1 and 1.2.

Design and function of an all-secondary explosive low-voltage electric detonator will be described. Results of the threshold values of current, voltage, energy will be presented together with the re-sponse times, the initiation capability gainst boosters of tetryl and the results of a few safety tests.

Les detonateurs de type Exploding Bridge Wire (EBW) et les Exploding Foil Initiators (EFI), developpes initialement pour des applications militaires ont, aussi trouve de nombreuses applications sur le marche commercial non militaire, tout en etant aujourd'hui encore utilises dans le domaine militaire. Bien qu'ils ne soient pas aussi frequemment utilises que les detonateurs a fil de pont plus connus, les EBW et les EFI presentent des avantages particuliers pour des applications speciales. Les avantages ainsi que les inconvenients sont presentes pour des concepts typiques.

The paper presents the results of a detailed technical investigations of the cause of the fire and subsequent explosion at Peterborough on 22 March 1989 involving a vehicle containing a mixed load of explosives and detonators. Tests were done to examine the sensitivenes and thermal stability of items of the load, and the behaviour of packaged explosives using drop, vibration and fire tests. Communication testing was undertaken with boxes of detonators, and ignition tests with boxes of fuseheads provided information relating to the characteristics of the fireballs generated. From analysis of the scientific data obtained, we conclude that the initial fire resulted from ignition of fusehead combs which were being transported in unauthorized and unsafe packaging, and we suggest a mechanism for detonatino involving the functioning of strewn detonators on fire-damaged boxes of explosives.

For more than forty years, CERCHAR1 's activities on explosives and related items have employed a staff of 10 to 20 people including 3 to 5 engineers. This staff, called LSEV2 , acts as the official French laboratory for testing and performing a variety of studies. The main research topics concern the safety in manufacturing of explosives, their transport, storage, and use, particularly in gassy and dusty mines. The same holds for hazardous chemicals that are potentially explosive or otherwise unstable. Related to these activities is the safety of the personnel involved in testing, which requires special attention to be paid to adapted procedures and instructions and to special devices or equipment, desiged for the most part by CERCHAR itself. Three examples of such designe are presented. Their objectives and advantages are disscussed. The first one is an explosion chamber for firing confined explosive charges up to 2 kilograms. This facility has the possrommy of being highly instrumented. Fragments formed in the detonation of deflagration regimes are totally stopped by the walls of the chamber. The second one is a cell device for daily storage of explosives. This device led to a very important reduction in the quantity of explosives handled by people in the same room. This avoids a possible catastrophic mass explosion when large samples are needed such as for modern, insensitive mining explosives. the design of the cell structure, based on ful scale experiments, limits an unexpected explosions to the contents of a single cell without propagation to the other cells. The third and last example presented is a movable wood barrier, located in areas where explosives are fired in the open. This barrier ensures a significant reducation in the blast effect. It allows the worker to stay in the immediate vicinty of charge during the final preparation stages i.e the connection of the detonator wires to the firing circuit.

Summary A problem in mining engineering concerning detonators for rock blasting is considered. Simple probability calculations give very useful information about the detonation sequence.

In order to find materials with increased specific electrical energy, especially for impact fuzes, the irreversible conversion of mechanical to electrical energy in ferroelectric ceramics of the Pb(Zr1-xTix) O3 type with a considerable proportion of zirconium is studied. The depolarization of the ceramics is measured for shock compressions between 0 and 30 kbar. The maximum electrical energy, obtained at about 18 kbar, is of the order of 1.8 J/cm3 with Pb(Zr0.965Ti0.035)03 + 1% Nb2O5 and of the order of 0.8 J/cm3 with a Pb(Zr0.54Ti0.46)03 + 1% Nb205. As an example for application, the initiation of a 3.5 ω bridge wire PETN detonator is described.

The report gives an account of the discussions and the agreements reached during the 7th meeting of the Commission together with the full texts of the 18 technical papers presented to the meeting. Recommended standards and testing procedures were finally approved for the following: Ballistic mortar Transmission of detonation of ion-exchanged explosives Test detonators with 0.6 g and 0.25 g PETN Method of testing the initiating strength of detonators. The following new themes were included in the plan for the next period of work of the Commission: Toxic fumes from explosives in blasting Initiation and stability of detonation of slurry and water gel explosives under different conditions Sensitivity of slurry and water gel explosives The underwater explosion test Deflagration and transition from deflagration to detonation. The Commission agreed on a change of its name. The new name will be: „EXTEST International Study Group for the Standardization of the Methods of Testing Explosives”. A suggestion for the Commission to seek a form for association with other international corporative bodies such as the International Organization for Standardization (ISO), suitable for furthering the objectives of the Commission, was discussed and will be further investigated. The next meeting of the Commission will be in 1978 in Czechoslovakia.

An experimental program is described in which the capacitor-discharge initiation characteristics of a detonator containing a vacuum-deposited thin-film chromium bridge were studied. The objective of the effort was to define the conditions that would result in overall function times of 10 μs or less. The threshold initiation energy of the detonator was in the range of 11.5 mJ–20.0 mJ. Consistent performance was obtained from a firing energy of 54 mJ, which was achieved by a 5-μF capacitor charged to 147 V. Under these conditions, the average overall function time was 4.2 μs, with a standard deviation of 0.2 μs. Other tests showed that at higher capacitances and lower voltages the function time increased substantially and became more nonreproducible, even though the stored energy was considerably above the threshold value.

The delay time of a column of pyrotechnic material when used in a delayed action electric detonator is defined as the time between the application of the initiating electrical impulse and the detonation of the explosive charge of the detonator. The effects of fuel/oxidant ratio and fuel surface area on the delay time have been measured for the silicon/red lead system. From the data obtained it has been possible to identify a possible reaction mechanism for this pyrotechnic composition.

HAB is a thermally- and hydrolytically-stable solid, easily prepared from available raw materials. It is not highly sensitive to shock, friction, or electrostatic charge, but is sensitive to some types of impact, although not to others. It shows preliminary promise for possible use as a substitute for normal lead styphnate in less-sensitive bridgewire detonators, and as a substitute for tetracene in percussion detonators, e.g. the M-42 primer. Easy ignition, and a high burning rate without detonation, suggest application as an igniter. HAB is not sufficiently powerful to dent an aluminum witness block; therefore, it would not be suitable as a replacement for lead azide as an intermediate detonator charge.

The test results of 320 units of a laser initiated microdetonator are summarized. The commercially fabricated units used a lead styphnate/lead azide/HMX (1 mg/13.5 mg) explosive train design contained in a miniature aluminum can that was capped with a glass-metal seal window. The test parameters were the laser energy, temperature, laser pulse duration, laser wavelength and nuclear radiation (5,000,000 rad of 1 MeV gamma rays). The performance parameters were the laser energy for ignition and the actuation response time.

The use of modified forms of the Rosenthal electrothermal equation to aid in the design of a capacitor discharge firing circuit for a specific detonator is described. The electrothermal parameters Cp and γ, representing the heat capacity of the bridge and the heat loss factor, respectively, were calculated from previously obtained firing data for the detonator. These calculations provided input to the design of a firing circuit utilizing electrolytic capacitors, which have a large value of electrical capacity but also a non-negligible internal resistance. Calculations were performed which (1) revealed the degrading effect on detonator initiation caused by too large a value of internal resistance, and (2) permitted selection of a particular capacitor that would allow reliable functioning of the detonator with initiation times of about 230 μs. The circuit was designed utilizing this capacitor, and in the experimental evaluation of the circuit the measured initiation times were compared with the calculated values. Good agreement between the two was documented, and the conclusion was reached that the detonator functioned reliably. The merits of the electrothermal analysis and the assumptions utilized therein relative to a vigorous heat transfer/reaction kinetics modeling of the flow of energy from the bridge into the explosive flash charge are discussed in detail.

— Fracture damage development in paraboloidal-ended cylindrical rods of Perspex due to stress waves initiated by explosive point loading at the flat end of a rod with a detonator, embedded in surrounding media of solid lead or atmospheric air is discussed. An attempt has been made to explain the form and the location of the terminal internal fractures and the spalls in terms of stress optics considering first and second reflections of the incident waves at the interfacial boundary and the energy distribution of the incident waves when reflected from a boundary or refracted into the surrounding medium.

The user of delay detonators require a number as great as possible of equidistant time steps. In the case of greater time steps this can lead to the danger of overlapping of burning times between two following time steps. To avoid this, a calculation method is presented for the correction of mean combustion periods that surely eliminates the overlapping of burning times. For very precisely working delay detonators an increase in the number of time steps is possible.