Detonation Of Charges Research Articles

Structural response of steel-concrete composite panels to near field simultaneous blast and fragmentation loading

Steel-concrete composite sandwich panels are used in blast doors or blast walls to protect personnel and equipment in explosive environments due to their superior performance against blast effects. In the design of such panels, most design methods treat blast and fragment loading independently for far-field explosions. However, the synergistic effects of combined blast and fragments loading should be accounted for in close-in explosion scenarios. In this study, a field test program was conducted to assess the damage of the steel-concrete composite panels subjected to close-in explosion of cased charges at various scaled distance between 0.39 and 0.78 m/kg1/3. Characterization test of cased charge detonation was performed to explore the combined loading effect. The analysis includes the pressure-time history from the cased charge detonation, distribution of the fragment masses and velocities over the test panels. The structural damage and response of the composite panels against the combined loading effects was measured. The results indicated that in addition to the damage from the blast wave, the panel was remarkably damaged by the fragment impact. Despite the significant structural damage, the panels maintained its structural integrity after the tests. Additionally, quasi-static load tests were conducted on the panels to quantify their load resistant differences in pristine condition and various damaged conditions due to the explosive effects.

Study of the effects of shallow-buried charge parameters on the lower limb injuries of occupant in special vehicle body

In the process of military missions, special vehicles often encounter shallow buried charge threats that will greatly affect the safety of the occupants. To study the integrated effects of shallow buried charge detonation point, height-to-diameter ratio, burial inclination, weight, and other key parameters on the lower limb injuries of occupant, this study was based on the special body of a shallow buried explosive test and numerical calculation methods. The reliability of the numerical model and the load effect mechanism of the shallow burial charge were studied. Based on this, the lower limb injuries response law of occupant was analyzed with respect to each parameter. The results showed that the bottom charge load mainly came from two-stage ejection loading, in which the first stage was a strong load with short-duration local impact loading and the second stage was a weak load with long-duration extended range loading. By comparing the lower limb injury response of occupant under different charge parameters, we found that the weight of charge had the greatest effect on the extent of occupant injury, followed by the height-to-diameter ratio and burial inclination, while the detonation position had a relatively small effect on the injury magnitude. Finally, a comprehensive prediction model of the lower limb injuries of occupant was obtained by using the Latin hypercube sampling method and the least-squares method, and it was verified that the model had a good matching accuracy.

Electric conductivity at the detonation of trinitrotoluene charges with different structures, densities, and additives

Electric conductivity at the detonation of trinitrotoluene charges with different structures, densities, and additives

Blast wave interaction during explosive detonation in a variable cross-sectional charge

Purpose. The research aims to assess the efficiency and performance of solid media destruction in directed blasting of a charge with variable cross-sectional shape. Methods. Numerical modelling of the blast wave interaction process is performed using the finite element method based on the Euler-Lagrange algorithm. The Johns-Wilkins-Lee equation of state is used to determine the pressure-volume dependences of medium destruction. Assessment of solid medium destruction mechanism during a directed blasting of a charge with variable cross-sectional shape is carried out based on polarization-optical method on models made of optically active material. Findings. Experimental studies of solid medium destruction by the action of directed blasting with a variable cross-section charge made it possible to determine the direction of blast wave propagation and its amplitude in stress wave, influencing the intensity of radial crack network formation in superposition areas, and directed perpendicularly to explosive cavity. At the same time, the average peak pressure in collision zone of two shock waves in centre of spherical cavity is approximately 1.48 and 1.84 times higher than that in weakly blast-loaded areas. It has been found that when two shock waves collide and superimpose on each other, the intensity of their impact increases. Moreover, the shock wave velocity in collision zone is higher than that of the radial shock wave. Originality. It has been determined that the maximum pressure values on the explosive cavity wall at the initiation points sharply increase and then gradually stabilize as the blast stress waves propagate and have an arbitrary distribution pattern. Three areas should be considered: not superimposed, weakly superimposed, and strongly superimposed. At each point of detonation, the pressure on explosive cavity wall will be minimal, while in the charge centre in the spherical insert zone, on the contrary, it will be maximal. In this case, the pressure in the central superposition area is about 2.84 times greater than at the initiation ends, and the nature of distribution changes according to a linear dependence. Practical implications. The performed research findings can serve as a basis for development of effective parameters of resource-saving methods for stripping hard rocks of complex structure in the conditions of ore mines.

Research of the Process of Electrochemical Deposition of Chromium in the Presence of a Composite Compound Based on Detonation Diamond-Containing Carbon

The purpose of the study is to develop a method for obtaining high-quality electrochemical chromium coating using a new type of diamond-containing additive that has significant advantages over traditionally used detonation nanodiamonds (DNA) in the form of aqueous suspensions. Detonation diamond-containing carbon (DDC) obtained by detonation of charges from tetryl was used as an additive. DDC contains 63,0 wt. % DNA and 4.4 wt. % non-combustible impurities. We used standard chromium electrolyte: CrO3 - 250 g/l, H2SO4 – 2,5 g/l, DNA – from 0,2 to 5 g/l, traditional methodologies and algorithm of experimentation. The scope of the study is limited to the creation and application of a specific, easy to handle and prepare formulation with DDC. DDC can be added to the standard chromium electrolyte directly or in the form of freshly prepared aqueous suspension, it is environmentally safe. The originality of the work lies in the application of a cheap diamond-containing product obtained directly after the explosion of an individual explosive (tetryl) and providing stability of DDC suspensions. An increase in microhardness of wear-resistant chrome coating by 1,5 times (up to 11 GPa) and hard chrome coating by 1,7 times (up to 13,3 GPa) was achieved. The wear resistance of the obtained coatings increased by 1,9 times. Concentration (per pure detonation nanodiamond (DNA)) from 0,63 to 3,15 g/l in the electrolyte (very low).

Design of a simplified cranial substitute with a modal behavior close to that of a human skull.

Individuals exposed to the propagation of shock waves generated by the detonation of explosive charges may suffer Traumatic Brain Injury. The mechanism of cranial deflection is one of many hypotheses that could explain the observed brain damage. To investigate this physical phenomenon in a reproducible manner, a new simplified cranial substitute was designed with a mechanical response close to that of a human skull when subjected to this type of loading. As a first step, a Finite Element Model was employed to dimension the new substitute. The objective was indeed to obtain a vibratory behavior close to that of a dry human skull over a wide range of frequencies up to 10kHz. As a second step, the Finite Element Model was used together with Experimental Modal Analyses to identify the vibration modes of the substitute. A shaker excited the structure via a metal rod, while a laser vibrometer recorded the induced vibrations at defined measurement points. The results showed that despite differences in material properties and geometry, the newly developed substitute has 10/13 natural frequencies in common with those of dry human skulls. When filled with a simulant of cerebral matter, it could therefore be used in future studies as an approximation to assess the mechanical response of a simplified skull substitute to a blast threat.

A high-order simulation method for compressible multiphase flows with condensed-phase explosive detonation in underwater explosions

This study introduces an efficient method designed for the simulation of compressible multiphase flows associated with explosive detonation, primarily in the context of underwater explosions. The proposed approach integrates three core components: the compressible Euler equations, the level-set equation, and the program burn model. Spatial terms of the compressible Euler equations undergo discretization using a fifth-order accuracy weighted essentially non-oscillation reconstruction, while the third-order total variation diminishing Runge–Kutta scheme manages the temporal terms. The level-set method ensures accurate tracking of the multiphase interface. To detail the transition from solid, non-reactive explosives to gaseous detonation products in the condensed charge's detonation reaction zone, the program burn model based on Zeldovich, von Neumann, Doering theory. The efficacy and accuracy of the incorporated program burn model and the multiphase interface capture method are employed through four benchmark tests, exhibiting excellent agreement with previously published data from alternative numerical methods or commercial software. In conclusion, applying the proposed method to four distinct engineering scenarios facilitates a comprehensive understanding of the inherent dynamics associated with detonation and shock wave generation and propagation.

Теоретична база обгрунтування збалансованого енергонасичення породного масиву підриванням комбінованих свердловинних зарядів

Теоретична база обгрунтування збалансованого енергонасичення породного масиву підриванням комбінованих свердловинних зарядів

Study of the coupling characteristics of damage elements with cased charge

In this paper, the coupling characteristics of fragments, detonation products and explosive shock wave have been studied. Although a large number of studies have been conducted to discuss the damage effects of structures under the combined loading of blast and fragments impact, there is a lack of research on the coupling characteristics of damage elements and their mechanism of action. This study uses the law of conservation of energy to propose a more reasonable method to evaluate the velocity of fragment. In addition, the isentropic expansion theory of bare charge detonation products is used to explore the expansion characteristics of cased charge detonation products, and the expansion process of cased charge detonation products can be divided into three phases. The results show that the limiting expansion volume of detonation products with cased charge is smaller than that of bare charge due to the inhibiting effect of the casing. Taking into account the energy absorbed in the crushing of the casing, the shock wave produced by the explosion of the cased charge is equal to the shock wave produced by the explosion of a given amount of bare charge, and the corresponding formula is given. Then, based on the known performance parameters of each damage element, the arrival time of the damage element at the target structure is systematically analyzed, and the coupling of the damage element is divided into five phases according to the arrival time, and the range of damage effect of each coupling phase is analyzed in two cases. Finally, a numerical simulation based on Euler's method is performed, and the theoretical results agree well with the numerical simulation results.

Bubble pulse arrival time calculations to determine SUS charge detonation depths

As part of the New England Seamount Acoustics (NESMA) project in 2023, experiments were conducted over the Atlantis II Seamount. A total of 216 Signal Underwater Sound (SUS) broadband explosives (150 1.1 oz and 66 1.8 lb net explosive weight) were deployed at multiple locations and two different design depths around the seamount. An acoustic recorder (SoundTrap ST4300), with four hydrophone channels of varying sensitivities, was deployed during each of the SUS events to record the signals generated by the explosives. The recorded signals include arrivals corresponding to the shock wave, subsequent bubble pulses and reflections from the sea surface and sea floor. The time between the first arrival and the bubble pulse was used to calculate the depth at which each SUS charge detonated. The resulting SUS detonation depths from the bubble pulse calculation were compared with depths obtained from surface and bottom reflections to assess the accuracy of the bubble pulse method. A comparison of the results from the two methods shows that using the bubble pulse interval to calculate the SUS detonation depth is reasonable and can be used in propagation models. [Work supported by Office of Naval Research Code 322OA and TFO.]

Анализ действия детонационного генератора низкоамплитудных импульсов давления регулируемой длительности

The paper presents results of the analysis conducted on the action of the low-amplitude pressure pulse detonation generator with adjustable duration, where the detonation wave affects the controlled compressible medium and propagates in the direction from the medium subjected to the shock wave compression. Analytical expressions are provided for a simple model of the process under study to calculate the pressure pulse amplitude-time characteristics on the compressible medium with the charge detonation product plane-symmetric flow and the compressible inert medium. The paper considers a scheme of experimental (laboratory) assembly. In its cylindrical channel, the detonation product quasi-one-dimensional effect on the controlled environment is realized. Results of registering dynamics of pressure alterations in the controlled environment were obtained. When comparing calculation and experiment results, the reasons causing their discrepancy were identified. If the assembly body is made of steel not subjected to heat treatment, then it becomes possible to use it five times (at least) with charges of the bulk explosives based on the hexogen with generating controlled pressure pulses of several kilobars in the condensed organic materials with duration of at least tens of microseconds. In this case, the pressure rise time at the pulse leading edge reaches approximately ten microseconds.

Layout considerations on compound survival shelters for blast mitigation: A finite-element approach

The safety of both military personnel and equipment in unstable regions has for a long time been a major issue and concern. Protective shelters with multiple configurations have been widely used to meet safety requirements. Since military compounds are subjected to different types of threats, such as the detonation of improvised explosive devices (IED), a good understanding of the response of such shielding structures to blast waves is critical. A three-dimensional finite element (FE) model of a corner-entry ISO 20 ft container HESCO-Bastion survival shelter is developed, validated and tested under the external detonation of explosive charges. The FE model is validated against experimental data and used to investigate the protective performance of the shelter by considering several design-related parameters, such as charge location, roof extension, interior corridor dimensions and the effect of venting and its location. Results are discussed in terms of peak overpressure and maximum impulse at discrete locations around the container, and it is found that the shelter is the least efficient in mitigating the blast load propagation when the explosive material is at an angle of 45° to the entrance. Also, while the protective roof at the entrance plays a significant role in protecting the container from air-borne threats, it is observed that it contributes to higher pressure and impulse data within the shelter, for detonations at ground level, with impulse amplifications as high as 94% when fully covering the entrance area. Contrarily, varying the distance between the container and the HESCO-Bastions is found to have minimal impact on the impulse, while naturally decreasing the peak pressure for increasing distances. Venting (through openings) can lead to up to 95% reduction in the peak pressure, whilst not affecting the impulse.

Analysis on lethality characteristics of shell-split warheads under explosive loads

Case cutting has been demonstrated as a means of warhead self-destruction, but few studies have analyzed it in detail. Based on the self-destruction of ammunition, the effect of warhead shell split including the shell fragmentation and scattering characteristics driven by charge detonation were studied. The results show that by cutting and splitting the shell of the warhead, the shell driven by the charge detonation can be hardly broken, and scatter in the form of large-size shell splits. The velocity of fragments speed decreases quickly, and the killing density is significantly reduced. The research results in this paper can provide a reference to the design and analysis on self-destruction of the warhead.

Formation and Evolution of a Dust Cloud as a Result of TNT Detonation in a Borehole: Numerical Simulation

Here, we present a numerical model for simulating the formation and evolution of the gas and dust cloud that forms after the detonation of high explosive charges in boreholes. This model provides a possible method for converting a substance ejected from an explosion funnel into discrete particles (smaller particles and stones) and calculating the movement of these condensed particles and their interaction with the air–gas flow; this method uses the framework of equations for multiphase media motion. For modeling of borehole explosion, we focused on the parameters of commercial blasting that are carried out at the Lebedinsky open pit. The results of simulating the initial stage of a borehole explosion with a mass of 1000 kg are presented in this paper. These results demonstrate the evolution of a gas and dust cloud, the change in the mass of particles of different sizes in the air over time, and their spatial distribution.

Numerical modeling of shaped charge jet penetration into ceramic–metal double-layered medium using smoothed particle hydrodynamics

The prediction of the damage effects of shaped charge projectile to ceramic–metal multi-layered target is a challenging task to address. In this paper, the smoothed particle hydrodynamics (SPH) method is applied to simulate the penetration of the metal jet generated by the shaped charge detonation into ceramic–metal double-layered plates. The presented SPH model incorporates different equations of states. Moreover, the elastic-perfectly plastic constitutive model and the Johnson–Holmquist-II material constitutive model were employed for modeling the mechanical behaviors of the solid materials in this study. Firstly, simulation of the high velocity impact process of a ceramic ball on a ceramic–metal double-layered plate was conducted to validate the presented constitutive model. After the validation of the numerical model, simulations of penetration of a shaped charge into a double-layered ceramic–metal plate by using millions of SPH particles were conducted. The simulation results (perforation diameter and debris cloud) are in good agreement with the available experimental data, which shows that our in-house SPH solver is capable of tackling the shaped charge detonation and its penetration into multi-layered structures very well. Furthermore, the presented SPH model can reproduce different types of fracture patterns observed in experiments and their dynamic formation processes.

Determination of the lifting height of dust particles after a mass explosion in an iron ore open pit

Open pit mining is accompanied by emissions of fine dust and hazardous gases into the atmosphere. This is related to the operation of open pit transport, drilling and blasting operations. The release of harmful components into the quarry space and the increase in their concentrations has a negative impact on the health of working personnel and leads to pollution of the environment. In doing so, the nature of fine dust and gases pollution depends on the mining technology and meteorological factors. The problem of reduced effectiveness of dust suppression methods after mass explosions in open pits is relate to insufficient research into the formation of dust and gas cloud. Additional theoretical and experimental research into the dust dynamics of blasting operations is therefore need. The article discusses the stages of formation of the dust and gas cloud after a mass explosion in an iron ore open pit. The results of experimental studies of the evolution of the dust and gas cloud at different points in time after the detonation of borehole charges are presented. Relations for determination of density and dynamic viscosity of gases, gas mixture and gas-dust aerosol are given. A formula for determining the time and height of ascent of spherical dust particles at the dynamic stage of dust and gas cloud formation is obtain. In this case, the assumption is madid that there is no mutual influence of the dynamic and thermal factors after detonation of the charges. The elevation of dust particles due to temperature differences during the heat stage of dust and gas cloud formation is determined. Based on the analysis of the calculation results, the duration of the dynamic stage of cloud formation is determined. It is established that, following the release of solid and gaseous detonation products into the atmosphere, a height distribution of dust particles is observed as a function of their diameter. That said during, the dynamic stage of dust and gas cloud formation, the height of dust particle lift is directly proportional to their diameter, while during the heat stage the inverse relationship is observe. That at the beginning of the thermal stage the deposition of coarse dust particles takes place are established. In this process, fine dust particles rise to a maximum height and are then carried outside the open pit by the airflow.

Assessment of the Sympathetic Detonation of Blasting Caps

The neutralization of improvised explosive devices (IEDs) involves the use of disrupting agents propelled explosively. Due to the special nature of such materials, a proper investigation of the parts most susceptible to sympathetic detonation is in order. The initiation of IEDs is caused by detonation products, shock waves, and propelled disruptive agents. In this paper, initiation of IED composition (acceptor charge) due to the neutralization system’s (donor charge’s) explosive charge detonation is evaluated based on the influence of the first two of the three above-mentioned factors. One of the most susceptible components of IEDs to sympathetic initiation is the blasting cap. Based on an experimental and numerical mix approach, blasting cap tendency to sympathetic detonation in open field had been investigated. The suitability of critical energy fluence and Chapman–Jouguet threshold criteria to the sympathetic detonation tendency of blasting caps was investigated. Experimental and numerical/analytical results describing the phenomenon are in agreement.

Progressive collapse analysis of prestressed concrete girder bridges using improved applied element method

AbstractIn this paper, the Improved Applied Element Method (IAEM), which was originally developed as an effective analysis technique for large-scale bonded and unbonded prestressed structures, is utilized to carry out failure modeling of prestressed bridges under different hazard loads. A typical prestressed concrete girder bridge is analyzed under two hazardous loading scenarios. The first one is applying a detonation charge located in the middle of the central span, while the second scenario is a sudden failure of a column representing a truck or a vessel colliding with the bridge pier. For both scenarios, the collapse analyses of the bridge structure after damage are explored. In addition, the mechanism and severity of damage in the bridge pier and deck are investigated. Both material and geometric nonlinearities are considered in the analysis. Moreover, it considers contact-impact, re-contact, and inertia effects, and hence, it can track the collapse stages of the structure as well as debris movement until the complete collapse of the structure. The results show a strong capability for simulating the total performance of the bridges from early the stages of loading until the total collapse, with a clear graphic representation of the collapse phenomena.

Differences in responses of square steel plates exposed to blast loads generated by cubic and spherical explosives

The differences in the responses of square steel plates subjected to blast loads of cubic and spherical charge explosions were investigated in the study. A finite element model (FEM) was developed by LS-DYNA, and the FEM was validated by experiment and UFC 3-340-02. Based on the validated numerical model, the incident and reflect loads of cubic and spherical detonations were compared. In the x-z plane, the incident pressures of cubic explosives are observed to be concentrated in the x and z directions while that of spherical charges are uniform in all directions. Furthermore, cubic explosives have substantially higher normal reflect pressures than spherical charges. For square steel plates, the results indicate that cubic explosives can produce more significant deformations and plastic damage than spherical explosives. Moreover, quantification metrics was proposed to assess the differences in responses of steel plates subjected to blast loads of cubic and spherical explosives. The ratios of average maximum displacement (Dam) under cubic and spherical charge detonation were analyzed, as well as the ratio of average residual displacement (Dar). Equivalent coefficient (ζ) was defined to equate a cubic explosive to a spherical explosive. Finally, a damage number for steel plates subjected to blast loads was presented. The relationships between damage number and displacements were created. The damage number and displacements have linear correlations. Moreover, the displacement ratios of steel plates under blast loads of cubic and spherical explosives can be approximated by using the damage number. The damage number can also be used to approximately derive the equivalent coefficients.

Acoustic characterisation of unexploded ordnance disposal in the North Sea using high order detonations.

Results are presented of acoustic measurements made during the disposal of 54 items of unexploded ordnance (UXO) in the North Sea during the pre-construction phase of two offshore windfarms. The disposals were conducted using high-order controlled detonation of donor charges placed on the seabed adjacent to the UXOs. The total charge masses ranged from 2.5kg to 295kg TNT equivalent, and acoustic measurements were made at ranges of 1.5km to 58km from the UXO. High-order detonations can present a risk of injury or death to marine mammals and other fauna from the high sound levels produced, and these results represent the largest data set of acoustic measurements ever assembled for publication. Acoustic measurements were also made on small scare charges, used as mitigation. The sound pressure pulses are presented with their spectra, and the levels of peak sound pressure and sound exposure are presented as a function of range from the source. Measured levels are compared to data from a shallow-water propagation model, and to widely-adopted exposure level thresholds used for marine mammals, illustrating the potential for injury at distances of several kilometres.