Detonation Products Of Explosives Research Articles

Extended JCZ3 Equation of State and JAGUAR Implementation for High Explosives

AbstractAn extended JCZ3 based equation of state for the modelling of high explosive detonation products has been implemented in the JAGUAR computer model. This development includes the parameterization of EXP‐6 potentials for individual products species, as well as mixing rules for the combination of species. Non‐linear variable metric optimization was used for the species parameterization, as well as for the solution of free energy minimized states. Explosive detonation and products expansion are typically modelled for JWL and JWLB high explosives thermodynamic equation of state development. An analytic c ylinder test model was developed for the comparison to experimental cylinder expansion test data and for the characterization of explosive products expansion and work output. Examples and comparisons to data are presented. Historically, streak photography was used for cylinder testing, whereas photon‐doppler velocimetry (PDV) is now standard. This has resulted in some changes in cylinder testing data reduction. A JAGUAR MSIAC web‐based application is currently under development for use by the MSIAC member nations.

Оценка качества капсюлей-детонаторов (с пиротехническим замедлением) неэлектрических систем инициирования по времени их срабатывания

Blasting operations in surface and underground mining are characterized by the need to protect the environment from harmful effects of the detonation products of explosives, the fly rock zone, the seismic manifestations of the blast, as well as airborne shock waves. Non-electric blasting systems by various manufacturers are used in Russia, but all of them have certain advantages and disadvantages. It can be stated that the blasting caps of the applied blasting system do not always correctly execute the firing times specified by their manufacturer. Mismatches of the actual firing times from the rated ones might be so great that the applied blasting systems sometimes produce disturbances in the order of charge firing, which, in turn, may cause detonation failure in the boreholes. Studies have shown that in order to reduce the risk of detonation failures, regardless of their causes, it is recommended to initiate the borehole at two points with placing the second primer in the upper part of the borehole, or using extended priming charges.

Identification of Aluminium Powder Properties for Modelling Free Air Explosions.

Aluminium is a component in many energetic formulations. Therefore, its combustion is one of the main thermochemical processes that govern the output from the energetics. Modelling aluminium combustion is a challenging task because the process is highly complex and difficult to measure. Here, tests of aluminium powder were conducted in an effort to isolate the burning of the aluminium and to determine an adequate representation of this process. Charges of 100 g and 500 g were tested, and the size of the Al/air cloud and the ratio of components in the Al/air mixture were determined, which has not been published previously. This information was used to assess the validity of the assumption that the detonation of the mixture was representative of the event. Parameters for the Jones–Wilkins–Lee equation of state for the explosive mixture and detonation products were defined. Simulations of the tests were performed, and the results were consistent with the field test data, indicating that detonation occurred when there was a mixture of 70–75% Al and 25–30% air by mass.

Natural and anthropogenic risks after a giant landslide in the Russian Far East

At the Bureiskoe Reservoir (Far East, Russia) in December 2018 at a temperature of 36°C below zero the giant landslide is occurred. Landslide with a total volume of 24.5 million m3 blocked the reservoir from one shore to the opposite one, disrupting the access of water to a large hydroelectric power station downstream. Blasting operations were carried out with the use of trinitrotoluene and hexogen to revive the water flow. As a result of the landslide natural hazards (direct impact of the landslide, and tsunami) were happened, and the further strong impact was caused by humans (blasting). Volatile organic compounds (VOCs) and elemental composition were accepted as the main indicators of water quality. Parameters of these indicators varied at different near-shore sites above and below the landslide area. More significant changes are recorded after blasting operations. Hexane and toluene dominated the water passing the artificial channel. The genesis of VOCs can be associated with the biogeochemical processes of methanogenesis, methanotrophy, and the detonation products of explosives. Mercury, methanol, toluene, and xylenes in water samples were detected. This is evidence of the presence of a prerequisite for the formation of toxic methylmercury, a risk factor for aquatic biota.

КУМУЛЯТИВНЫЕ ЗАРЯДЫ С ТОНКИМИ И СВЕРХТОНКИМИ ОБЛИЦОВКАМИ

The aim of the research is to study the formation of cumulative jets in charges with cumulative facings with a wall thickness of the order of the thickness of the jet-forming layer in classical charges. Based on mathematical modeling and experiments, it is shown that in such charges, the detonation products of explosives can play the role of an additional body that affects the axial velocity of the lin-ing throwing and leads to a collapse angle of more than 180 degrees. In this process, the mass of the jet is greater than the mass of the pestle. For the first time, corrugations were experimentally detected on the surface of the lining during its explosive compression. Corrugations may occur on the surface of the lining, leading to instability of the cumulative jet formation process. As a result of the study, it was found that the minimum wall thickness of the cladding is mainly determined by the instability of its surface (the appearance of corrugations on its surface).

Thermal effect of explosive detonation products on a flyer plate in the explosive welding of metals

In this study, a combined simulation and experimental method is suggested to determine the heat flow rate produced by detonation products with a planar thermocouple battery placed inside the test medium. A series of experiments was conducted to measure the temperature of products produced by the detonation of ammonite mixed with quartz sand, sodium bicarbonate, and talc over a detonation velocity range of 2–2.8 km/s. By solving the inverse heat conduction problem, we can obtain a time dependent relation for heat transfer from the detonation products to the flyer plate. It is shown that the temperature of the detonation products in the mixtures and the maximum heat flow to the flyer plate rise with an increase in the detonation rate. A quantitative evaluation of heat transfer to the flyer plate by the explosive detonation products is conducted. It is demonstrated that when thin plates (foils) are used as flyer plates, a preheating of the contact area of the colliding components occurs.

Measuring method of dynamic fracture toughness of mode I crack under blasting using a rectangle specimen with a crack and edge notches

In order to study fracture toughness of mode I crack under blast load, a new specimen of a rectangle plate with a crack and edge notches (RPCEN) was proposed in this study. The PMMA was selected to prepare the RPCEN specimens. The testing system consists of a dynamic strain amplifier, an oscilloscope, a constant source, strain gauges and crack propagation gauges. The strain gauges and crack propagation gauges (CPGs) were used to measure the blast load and crack propagation speed, respectively. The scanning electron microscope was applied in studying the property of fracture surface. The explicit dynamic software AUTODYN was applied in simulating crack dynamic propagation behavior. The JWL equation of state (EOS) was applied to the explosive detonation products, and a linear EOS was used to describe the relationship between pressure and density of PMMA. A modified principle stress failure criterion was employed to assess the material state. The experimental-numerical method was used to determine the dynamic initiation and propagation toughness of the PMMA. The dynamic stress intensity factors (DSIFs) were calculated by the finite element code ABAQUS. The experimental and numerical results show that: (1) The RPCEN specimen proposed in this paper has the function to minimize the reflected tensile stress waves; (2) During crack propagation the fracture surface roughness and the nucleation rate increase with crack propagation speed; (3) Crack propagation speed is not a constant, and propagation toughness is related to the crack propagation speed.

DEVELOPMENT OF INDIVIDUAL ASPECTS OF CONTAINER METHOD OF FIRE EXTINGUISHING

Currently, the creation of fundamentally new technical means of fire extinguishing and the development of new methods for delivering fire extinguishing substances to a remote distance when extinguishing complex fires is the actual scientific and technical problem. The fire fighting equipment currently used in the territorial divisions of the SES of Ukraine does not allow delivering of fire extinguishing substances at a distance of 100 m and more. Existing fire fighting equipment is designed to deliver water, aqueous solutions and foams at a distance of up to 100 meters, as well as dry chemicals at a distance of up to 70 meters. Today various researchers are developing technical means and methods for remote delivery of such fire extinguishing agents as aerosol-forming compounds, dry chemical powders, fire extinguishing freons, solid carbon dioxide and organometallic compounds. At the same time, the use of the considered fire extinguishing agents did not become widespread in the fire and rescue units due to insufficient development of technical means and methods of delivery. To solve the problem of delivering fire extinguishing substances to a remote distance while extinguishing complex fires, it was proposed to use a barrelled fire extinguishing system, which ensures high-precision delivery by throwing the containers filled with extinguishing agent directly into the combustion zone along the ballistic trajectory. The analysis of various fire extinguishing substances and compositions for use in containers showed that to achieve the highest efficiency of fire extinguishing, it is advisable to use dry chemical powders. As a result of the study of the use of dry chemical powders as container fillers, the mechanics of the fire extinguishing action of dry chemical compositions after releasing from the container by excessive pressure, created by detonation products of explosives, was investigated. A method for determining the total mass of dry chemical powder and the required number of containers filled with dry chemical powder for extinguishing class A and B fires has been developed. Keywords

A Practical Method to Evaluate the Afterburning Energy of Aluminized Explosives Based on a Simple Sleeve‐Slider Apparatus and Detonation Test

AbstractEvaluation of the afterburning energy of aluminized explosives is challenging. An experimental method based on a simple sleeve‐slider apparatus and detonation test is proposed in the present work by which the afterburning energy and its releasing rate can be calculated indirectly. When a little charge of aluminized explosive is detonated in a sleeve, the slider will be propelled rapidly by the detonation products inside the sleeve. Only the displacement history of the slider needs to be recorded by high speed photography, and the pressure and the specific volume of the aluminized explosive detonation products with time can be derived. Assuming the slider is rigid enough and the pressure is uniform in the sleeve, the afterburning energy can be evaluated practically. Before actual experiments are conducted, numerical simulations are used to validate the assumptions of the method; then, the experimental apparatus is designed, and several detonation tests are conducted. For comparison purposes, pure TNT and aluminized explosives are used in the experiments, and the results reveal that pure TNT does not release afterburning energy, which is expected, while aluminized explosive products release a large amount of afterburning energy, which makes the pressure decay more slowly. The afterburning energy rate is also obtained.

Understanding the phase separation of N2/H2O and CO2/H2O binary systems through reactive force fields-based molecular dynamics simulations

Phase separation has a considerable effect on the detonation performances of explosives, but its mechanism has seldom been studied in terms of the interatomic interaction through molecular modeling. The binary mixtures of molecular N2, CO2, and H2O, which are the key components of detonation products of common explosives, with high density and at high temperature were investigated by using the reactive force fields-based molecular dynamics simulations. The mixing and demixing behaviors of N2/H2O and CO2/H2O systems were compared to distinguish the driven forces of phase separation. The N2/H2O mixtures with high density exhibit a remarkable phase separation at low temperature, while the CO2/H2O mixtures are mixing in a wide range of density and temperature. Similar changes in the repulsive van der Waals energy were found for all the studied systems. However, the corresponding changes in the attractive Coulomb energy are quite different for the mixing and demixing systems. Moreover, the polarization effect in dense systems contributes greatly to the Coulomb interaction. The Coulomb attraction is thus responsible for the phase separation of the dense systems under extreme conditions.

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.

ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ ТРЕХМЕРНЫХ ПРОЦЕССОВ РАЗГОНА УПРУГОПЛАСТИЧЕСКИХ ТЕЛ ВЗРЫВОМ

A methodology for numerically modeling 3D processes of acceleration of deformable bodies by detonation products of solid explosives in the air is described. Simultaneous motion of the explosion products, the air and the elastoplastic medium is numerically analyzed in Euler variables, using a modified Godunov scheme, which is applicable for both fluid dynamics and elastoplastic flows, and an exact solution of Riemann problem of discontinuity breakage in the media and along the gas-elastic body interface. The methodology uses three types of spatial grids. The grids of the first type are sets of triangles (STL files) defining the surfaces of the objects and updating those surfaces in the process of motion. The grids of the second type are base fixed Cartesian grids nested into each medium. The grids of the third type are local orthogonal movable grids coupled with each of the triangles of the grids of the first type. The integration of dynamic equations of continua and mutual interpolation of parameters among the different kinds of grids is done on base and local grids. To simulate the detonation propagation process in a solid explosive, an algorithm based on Huygens principle and the account of energy release upon the arrival of the detonation wave into the integrated cell are used. Examples of numerically modeling propagation of elastic and elastoplastic disc-shaped, tetrahedral and cubic bodies of various materials adjacent to the charge are given. The results of the analyses testify to the applicability of the above methodology for modeling coupled processes of acceleration of deform-able bodies by detonation products up to deceleration in the ambient medium. Certain laws of the acceleration process have been found for the case where detonation is initiated in the center of a spherical charge. In particular, the duration of the acceleration of a body is comparable with the time of the arrival of the detonation wave at the surface of the contact; the major residual strains altering the geometry of the bodies occur at the initial stage of the acceleration and affect both the interaction with the detonation products and the parameters of the motion of the bodies; the final acceleration velocity is observed to depend considerably on the initial geometry of the accelerated body, its orientation relative to the detonation front and the deformation properties for the same mass.Keywords: modeling, detonation, 3D processes, multi-grid approach, interpolation, Godunov scheme, nonlinear coupled problems, aeroelastoplasticity, acceleration of bodies.

A New Experimental Field Study of the Effects of Explosive Detonation Products on Seismic Radiation

ABSTRACT Weston Geophysical Corp. conducted a series of chemical explosions using various explosives with different properties to investigate their effect on seismic signatures. Previous experimental data from the New England Damage Experiment (e.g., Martin et al. , 2012) suggest that low‐frequency P ‐wave amplitudes are affected by the explosive velocity of detonation and by the thermodynamic characteristics of gaseous explosive products (Stroujkova, 2015). The new experiment conducted in New Hampshire in 2016 was designed to isolate the effects of the amount of the explosive gases using aluminized and nonaluminized explosive pairs. The explosions were recorded using a network of seismometers and accelerometers fielded from near‐source to local distances. Seismic data from this experiment provide ground‐truth data that may be useful for future comparative studies of yield, based on seismic‐waveform analysis.

Correlation of electrical conductivity in the detonation of condensed explosives with their carbon content

This paper presents the comparative analysis of the results of more than fifty experiments on measuring the electrical conductivity of detonation products of RDX, HMX, PETN, TNT, and TATB-based explosives. It is revealed that there is a correlation between the electrical conductivity and the mass fraction of carbon both in the chemical spike and at the Chapman–Jouguet point.

Determination of the state parameters of explosive detonation products by computational inverse method

A computational inverse method is presented to determine the state parameters of Jones-Wilkins-Lee (JWL) equation of explosive detonation products based on cylinder test. In this method, the inverse problem of identifying the JWL parameters is formulated through minimizing the errors of the measured radial displacements on the cylinder surface and those computed by the forward solver. An available numerical model simulated by finite element method is built for the sake of obtaining results using the given JWL parameters. Because of the difference of coordinate systems between experiment and numerical model, it is necessary to conduct the transformation between the two coordinate systems. The sensitivity analysis method is adopted to evaluate the influence of the JWL parameters on the responses and find out the parameters those are suitable to be identified. In order to improve the computational efficiency, radial basis function approximate model is constructed to replace the time-consuming numerical model. In the process of constructing approximate model, the truncated singular value decomposition method is used to deal with the ill-condition of the model. At last, the intergeneration projection genetic algorithm is adopted to identify the parameters. The numerical results demonstrate that the proposed inverse method is potentially available to effectively identify the JWL parameters.

On the reaction of detonation products of condensed explosives with the ambient air

The propellant performance and the velocity of expansion of detonation products of explosives based on RDX and HMX and their mixtures with particulate Al were investigated. Measurements were performed in air at atmospheric pressure and in rarefied air. Comparison of the results shows that the detonation products of explosives, including those containing no Al additives, react with the surrounding air. The completeness of the reaction increases with increasing velocity of detonation products in air.

Numerical models for afterburning of TNT detonation products in air

Afterburning occurs when fuel-rich explosive detonation products react with oxygen in the surrounding atmosphere. This energy release can further contribute to the air blast, resulting in a more severe explosion hazard particularly in confined scenarios. The primary objective of this study was to investigate the influence of the products equation of state (EOS) on the prediction of the efficiency of trinitrotoluene (TNT) afterburning and the times of arrival of reverberating shock waves in a closed chamber. A new EOS is proposed, denoted the Afterburning (AB) EOS. This EOS employs the JWL EOS in the high pressure regime, transitioning to a Variable-Gamma (VG) EOS at lower pressures. Simulations of three TNT charges suspended in a \(26\,\hbox {m}^3\) explosion chamber were performed. When compared to numerical results using existing methods, it was determined that the Afterburning EOS delays the shock arrival times giving better agreement with the experimental measurements in the early to mid time. In the late time, the Afterburning EOS roughly halved the error between the experimental measurements and results obtained using existing methods. Use of the Afterburning EOS for products with the Variable-Gamma EOS for the surrounding air further significantly improved results, both in the transient solution and the quasi-static pressure. This final combination of EOS and mixture model is recommended for future studies involving afterburning explosives, particularly those in partial and full confinement.

Numerical method to discuss the mechanism of nano-Mn ferrite powder preparation by detonation of emulsion explosives

In the present research, the phase distribution of the detonation products of emulsion explosives used to prepare nano-MnFe2O4 powders by detonation is simulated by a numerical method. The mechanism of nano-MnFe2O4 powder synthesis via detonation of emulsion explosives is discussed and explained. The results obtained indicate that FeO and MnO form in the reaction zone before the Chapman-Jouguet detonation state is reached; these oxides react with surplus oxygen in air during the decrease in temperature and pressure, resulting in MnFe2O4 generation.

Molecular dynamics and kinetic study of carbon coagulation in the release wave of detonation products

We present a combined molecular dynamics and kinetic study of a carbon cluster aggregation process in thermodynamic conditions relevant for the detonation products of oxygen deficient explosives. Molecular dynamics simulations with the LCBOPII potential under gigapascal pressure and high temperatures indicate that (i) the cluster motion in the detonation gas is compatible with Brownian diffusion and (ii) the coalescence probability is 100% for two clusters entering the interaction cutoff distance. We used these results for a subsequent kinetic study with the Smoluchowski model, with realistic models applied for the physical parameters such as viscosity and cluster size. We found that purely aggregational kinetics yield too fast clustering, with moderate influence of the model parameters. In agreement with previous studies, the introduction of surface reactivity through a simple kinetic model is necessary to approach the clustering time scales suggested by experiments (1000 atoms after 100 ns, 10 000 atoms after 1 μs). However, these models fail to reach all experimental criteria simultaneously and more complex modelling of the surface process seems desirable to go beyond these current limitations.

A discrete particle approach to simulate the combined effect of blast and sand impact loading of steel plates

The structural response of a stainless steel plate subjected to the combined blast and sand impact loading from a buried charge has been investigated using a fully coupled approach in which a discrete particle method is used to determine the load due to the high explosive detonation products, the air shock and the sand, and a finite element method predicts the plate deflection. The discrete particle method is based on rigid, spherical particles that transfer forces between each other during collisions. This method, which is based on a Lagrangian formulation, has several advantages over coupled Lagrangian–Eulerian approaches as both advection errors and severe contact problems are avoided. The method has been validated against experimental tests where spherical 150 g C-4 charges were detonated at various stand-off distances from square, edge-clamped 3.4 mm thick AL-6XN stainless steel plates. The experiments were carried out for a bare charge, a charge enclosed in dry sand and a charge enclosed in fully saturated wet sand. The particle-based method is able to describe the physical interactions between the explosive reaction products and soil particles leading to a realistic prediction of the sand ejecta speed and momentum. Good quantitative agreement between the experimental and predicted deformation response of the plates is also obtained.