Blast Wave Propagation Research Articles

Numerical assessment of the human body response to a ground-level explosion

This paper presents the results of a numerical analysis of the behaviour of a human body after a ground-level explosion. The explosions were generated by condensed charges for different stand-off distances and various masses of explosive. The detonations points were located at distances of 1.0 and 2.0 meters from the dummy (human model) obstacle. The different masses of spherically-shaped TNT charges (0.4–1.0 kg) were initiated centrally. The blast wave propagation was generated using a coupled numerical design, which included Eulerian and Lagrangian descriptions for different domains, i.e. the dummy, air, and explosive domains.The main objective of this work was to present the actual pressures and accelerations around the dummy and the body motion caused by the rapid shock of the pressure action. Reaction forces and moments of anatomical joints were provided. Furthermore, the safety criteria presented in the official standards were compared to the simulation results.In this research, different positions against the loading masses were analysed. In each analysis the same standing human model was used. The dummy geometry was based on a medium size male (1.79 m, 84.8 kg). The human body was modelled as consisting of separate, rigid parts (with adequate masses and inertia moments) connected by joints exhibiting nonlinear behaviour. Anatomical ranges of motion were taken into consideration, and a dedicated numerical technique was proposed to model the resistance moment vs. the range of motion relations for the most important human body joints.

A One-Way Coupled Euler and Parabolic Model for Outdoor Blast Wave Simulation in Real Environment

Aerial blast wave propagation is affected by numerous physical parameters such as the source energy, the topography, the ground nature, or the atmospheric conditions. Direct high performance computing simulations is a valuable tool, but remains extremely costly in complex environment which limits the number of simulations. It is best used locally or to build reference solutions useful for the evaluation of simplified fast running models. Indeed, as the blast wave propagates, its strength weakens and after some distance, linear acoustic theory may be valuable. Here, we present the results of a one-way coupling procedure between a nonlinear Euler direct simulation code for the near field, including the detonation phase, and a parabolic linear acoustic model for the far field. Both models take into account for topography and atmospheric conditions. We show that, compared to the full Euler simulations, the coupling procedure provides accurate results at a reduced computational cost for blast wave propagation in the vicinity of an actual pyrotechnic site. The quality of the signals is also improved in comparison with classical parabolic simulations started with an analytical solution.

Blast wave propagation in survival shelters: experimental analysis and numerical modelling

The propagation of blast and shock waves in confined environments is a complex phenomenon; yet, being able to derive valid predictions of such phenomena is highly relevant, for example, when it comes to the assessment of protection of personnel in military environments. This study looks at the propagation of blast waves inside a compound survival shelter. Experimental analyses are performed on a small-scale model of the actual configuration of the shelter subjected to the detonation of an explosive charge at different locations close to its entrance. Pressure-time signals are recorded on a number of locations in the model. A numerical model is also developed to complement the experimental programme, based on the explicit finite element (FE) code LS-DYNA. The recorded experimental data (e.g., pressure and impulse) are compared with the numerical predictions to validate the FE model. The authors discuss two different modelling approaches (the Lagrangian and the MM-ALE formulations) and analyse the influence of using a different number of ambient layers, the advection method, the time-step size, and level of discretisation. The proposed numerical model predicts and captures the relevant stages of the propagation of the shock wave very well, with error levels on the resulting specific impulse always lower than 19% when compared to the experimental observations.

Blast loading model of the RC column under close-in explosion induced by the double-end-initiation explosive cylinder

Charge configuration has a significant impact on the damage of structural components subjected to close-in explosion. To develop a blast loading model on the RC column that can consider the charge shape and detonation configuration, a series of field tests of close-in explosion initiated at two ends of an explosive cylinder (double-end-initiation) were carried out. Highly-centralized blast loading histories were recorded on the mid-span area of the RC column in the field test. A detailed numerical model was developed in the commercial software AUTODYN, which showed a good agreement with the test data. The influences of charge shape, diameter-to-length (D/L) ratio, scaled distance, and detonation position on the overpressure and impulse were discussed. Analytical results reveal that the blast wave propagation and loadings on the column component under close-in explosion are significantly dependent on both shape and initiation-point, which is far different from that of the far-field explosion. The peak reflected overpressure and impulse are up to 3.5 and 2 times larger than those of the center-point-initiated charge, which is actually induced by the self-Mach-reflection of close-in double-end-initiation. An applicable blast loading model under close-in explosion induced by the double-end-initiation explosive cylinder considering D/L ratio and scaled distance was finally established based on the test data and numerical calculations.

Application of the four-dimensional lattice spring model for blasting wave propagation around the underground rock cavern

This paper studies the propagation and attenuation of blasting wave induced by explosion in underground rock cavern by employing the newly developed four-dimensional lattice spring model (4D-LSM). The non-reflection viscous boundary condition was implemented in the 4D-LSM to reduce the computing resources of full-scale simulation of blasting wave propagation in the practical engineering. Then, a number of damping models were developed and implemented in the 4D-LSM to describe the attenuation of blasting wave in the rock mass. In addition, the influence of the loading form of blast load and damping models on the propagation and attenuation of blasting wave were studied by comparing with the field test data in details. It was found that the loading form of a triangular blast stress wave with an equivalent pressure wave and the coupled damping model could lead the 4D-LSM producing a reasonable fitting over the field test data in terms of both the blasting waveform recorded at a given measuring point and attenuation results from a number of measuring points. Our study provides a basis for the further application of the 4D-LSM as an alternative numerical tool in modeling the blasting wave propagation problems in rock engineering.

Solution of the Noh problem with an arbitrary equation of state.

The classic self-similar solutions of the nonstationary compressible Euler equations obtained for a blast-wave propagation (Sedov, Taylor, and von Neumann), a shock-wave implosion (Guderley, Landau, and Stanyukovich), or an impulsive loading of a planar target (von Hoerner, Häfele, and Zel'dovich) have all been derived for a polytropic ideal gas. None of them can be generalized for a fluid with an arbitrary equation of state (EOS), such as the van der Waals EOS of a non-ideal-gas or a three-term EOS of a condensed material. We demonstrate here that the Noh accretion-shock problem is an exception. Its self-similar solutions exist in cylindrical and spherical geometry for fluids and materials with an arbitrary EOS. Such solutions for finite accretion-shock strength and nonuniform inflow velocity are constructed semianalytically with a model three-term equation of state that includes cold, thermal ion (lattice), and thermal electron contributions to the pressure and internal energy. Examples are presented for aluminum and copper. Other material- and EOS-specific semianalytic solutions of the Noh problem can be easily constructed using the same method for any material that in the pressure range of interest can be approximated as a dissipation-free fluid with an arbitrary equation of state.

Transition from nonlocal electron transport to radiative regime in an expanding blast wave

We have investigated the formation, evolution, and late-time propagation of a laser-generated cylindrical blast wave (BW). The whole blast wave evolution over timescales of several nanoseconds was reconstructed experimentally (via temporally resolved interferometric measurements) and via hydrodynamic simulations that included modeling of nonlocal electron transport and radiation diffusion. Comparison between the experimental results and the simulations indicates that the early expansion phase is characterised by nonlocal electron heat transport causing energy spread on times shorter than the typical timescales for hydrodynamic expansion. Nonlocal electron transport ionizes the gas ahead of the plasma front and gives rise to a smooth radial density gradient. At later times, once the shock is launched and the BW is formed, radiation results in reduced shock velocity compared to the adiabatic case. These investigations provide a suitable and effective platform to benchmark the inclusion of kinetic and radiative effects in fluid modeling of the plasma dynamics over timescales that may be inaccessible to fully kinetic simulations.

Test and analysis of blast wave in mortar test block

A strain gauge system poured in a mortar test block was used to study the propagation of blast waves generated by explosive charges. The shock waves were recorded with a super dynamic strain test system using strain gauges. The measured wave-forms were analyzed. The results show that the propagation of the blast wave in the experiment is mainly manifested by the joint action of the shock wave and the reflected tensile wave, and the action time is about 6 μs and 15 μs, respectively. At the same measuring point, the peak value of strain wave reaches 104 με, and the peak strain rate reaches 106 s−1. The attenuation of radial strain wave is faster than that of tangential strain wave, while the attenuation of gas is not obvious, and the compression strain on rock is greater than the tensile strain. Within the scope of the study, the loading of the blast wave is greater than that of the unloading. In the radial direction, with the increase of distance, the loading and unloading of shock wave on rock all showed a declining trend. The loading effect of the reflected tensile wave did not decay, and the unloading effect attenuated weakly. In the tangential direction, the loading effect of the shock wave on the rock first decreases and then increases, and the unloading damage of rock increases slightly. The loading effect of the reflected tensile wave on the rock first decreases and then increases, while the unloading damage nearly unchanged.

Flow structure generated by laser-induced blast wave propagation through the boundary layer of a flat plate

Laser energy deposition generates localized flow structures that can be used as flow control devices in high-speed flows. In the present study, the interaction between a laser-induced blast wave and an incoming laminar boundary layer on a flat plate was experimentally investigated at a Mach 5 flow with three different unit Reynolds numbers. A hemispherical laser-induced blast wave (LIBW) is induced by focusing a 532 nm pulsed Nd:YAG laser beam on the surface of the plate. The hemispherical shaped fore wave front of the LIBW is locally transformed to an oblique shape, which results in a laser-induced oblique shock wave (LIOSW). As LIOSW propagates through the laminar boundary layer increases its thickness. With laser energy deposition near the leading edge of the flat plate, the LIOSW interacts and influences the leading edge shock wave (LSW). This interaction could contribute to the modulation of the LSW in scramjet intakes. A weak shock limb generated at the shape transition point of the LIBW or thermal spot due to laser-induced gas breakdown causes the boundary layer perturbation. The geometrical pattern produced due to the interaction between the LIOSW and the disturbed boundary layer remains similar to itself as it grows with time as well as at different local Reynolds numbers, 2.2×105 to 5.7×105.

Blast hazard impact on V-shape composite panel performance

The terrorist attacks have been increased during the last few years. Blast wave propagation is a great engineering challenge to protect structures such as vehicles and buildings. Mitigation systems used to protect the structures remain a sophisticated engineering problem.In this study, the V-shape composite structure is studied as a mitigation system to protect the bottom of vehicles against blast impact. The reviewed field blast test is used from another research conducted by Mazek et al.[1] to verify the proposed numerical model of the V-shape composite structures under blast effect. The numerical model is proposed by 3-D nonlinear finite element model (FEM).The displacement-time history of the V-shape composite (VSC) structure is presented as the blast wave propagates. The impact of the V-shape panel inclination on the V-shape composite structure performance is analyzed and presented under the blast effect. There is a good agreement between the results obtained by both the field blast test and the numerical model. The VCS structure improves the armored panel performance under the vehicles based on the impact of detonating different TNT explosive charges.

Blast Hazard Impact on V-Shape Composite Panel Performance

The terrorist attacks have been increased during the last few years. Blast wave propagation is a great engineering challenge to protect structures such as vehicles and buildings. Mitigation systems used to protect the structures remain a sophisticated engineering problem.In this study, the V-shape composite structure is studied as a mitigation system to protect the bottom of vehicles against blast impact. The reviewed field blast test is used from another research conducted by Mazek et al.[1] to verify the proposed numerical model of the V-shape composite structures under blast effect. The numerical model is proposed by 3-D nonlinear finite element model (FEM).The displacement-time history of the V-shape composite (VSC) structure is presented as the blast wave propagates. The impact of the V-shape panel inclination on the V-shape composite structure performance is analyzed and presented under the blast effect. There is a good agreement between the results obtained by both the field blast test and the numerical model. The VCS structure improves the armored panel performance under the vehicles based on the impact of detonating different TNT explosive charges.

Numerical study for dynamic response of marine sediments subjected to underwater explosion

This paper developed a three-dimensional numerical model for saturated soil response induced by underwater explosion in marine environment. Unlike previous studies, three new features are included in the present model: (1) genuine detonation with real explosive materials; (2) coupled ALE (Arbitrary-Lagrangian-Eulerian)-Lagrangian algorithm for large seabed deformation; and (3) u-p formulation considering pore water pressure effect. The proposed explosion model is validated against experiment data available in the literature. Several parametric studies are carried out to investigate seabed response considering various soil types and TNT equivalent. Time series of total stress and pore pressure from sandy bed and clayey bed subjected to explosive loads are presented. Special attention is given to the distribution of peak total stress and pore pressure during propagation of blast wave. To facilitate engineering practice, a series of formulas for evaluating attenuation of peak total stress and pore water pressure are proposed.

A one-way coupled Euler and Parabolic model for outdoor blast wave simulation in real environment

Aerial blast wave propagation is affected by numerous physical parameters such as the source energy, the topography, the ground nature, or the atmospheric conditions. Direct high performance comput...

Experimental and numerical investigation on blast wave propagation in soil structure

This paper presents a study on blast wave propagation in a soil structure when subjected to a surface air blast loading. The experimental work utilized the use of plastic explosive of 1 kg weight (PE4) in order to create a spherical blast wave at a fixed standoff distance. The experimental results were then compared with the numerical simulation model computed using LSDYNA3D. Although the computed simulation and experimental results showed large difference in terms of values, but both results provide a similar trend in terms of blast peak overpressure.

Numerical Simulation of Blast Wave Due to Meteorite Explosion in Stratified Atmosphere

This paper investigates the applicability of direct simulation considering a stratified atmosphere to an unsteady analysis of a blast wave caused by a meteorite explosion. Axi-symmetric Euler equations with a gravity term that considers a horizontally stratified atmosphere are numerically solved to analyze blast wave propagation from the source of meteorite explosion to the ground. Computations are made to reproduce the blast wave generated by the Chelyabinsk meteorite in 2013, assuming a spherically uniform high-pressure and high-temperature core as the source of explosion. The amount of energy released by the explosion at an altitude of 25 km is assumed to be 500 kt of trinitrotoluene, and the computational domain ranges over a radial distance of 50 km from the center of the explosion. The simulation results in a uniform atmosphere agree well with the results of well-known Brode’s empirical formula, and the blast wave obtained from the simulation considering a standard atmosphere is expected to cause serious damage to the ground, as experienced at the time of the Chelyabinsk event. Moreover, the simulation results clarify the characteristics of blast wave propagation through uniform, isothermal, and standard atmospheres.

Analysis of Blast Wave Parameters Depending on Air Mesh Size

Results of numerical simulations of explosion events greatly depend on the mesh size. Since these simulations demand large amounts of processing time, it is necessary to identify an optimal mesh size that will speed up the calculation and give adequate results. To obtain optimal mesh sizes for further large‐scale numerical simulations of blast wave interactions with overpasses, mesh size convergence tests were conducted for incident and reflected blast waves for close range bursts (up to 5 m). Ansys Autodyn hydrocode software was used for blast modelling in axisymmetric environment for incident pressures and in a 3D environment for reflected pressures. In the axisymmetric environment only the blast wave propagation through the air was considered, and in 3D environment blast wave interaction and reflection of a rigid surface were considered. Analysis showed that numerical results greatly depend on the mesh size and Richardson extrapolation was used for extrapolating optimal mesh size for considered blast scenarios.

Computational Analysis for Reducing Jet Wind from Blast Wave Generator

Computational Analysis for Reducing Jet Wind from Blast Wave Generator

Mechanism Study on Elevation Effect of Blast Wave Propagation in High Side Wall of Deep Underground Powerhouse

In view of the influence of blasting excavation in the deep burial underground powerhouse on the dynamic disturbance and blasting vibration of side wall and surrounding rock, the blasting vibration test method is often used for on‐site monitoring and control. Taking the blasting excavation of the high side wall of an underground powerhouse of a hydropower station as the engineering background, a long‐term blasting vibration test is carried out on the site. The measuring points are arranged along the elevation direction and horizontal direction of the high side wall of the powerhouse. Through analyzing and comparing the blasting vibration velocity values extracted from a large number of on‐site measured data in the elevation direction, an interesting phenomenon is found. The measured vibration velocity of the rock anchor beam in the area far away from the blasting is greater than that in the area near the blasting, and the vibration velocity after the casting of the rock anchor beam is greater than that before the casting. In order to avoid the randomness and contingency of the measured data, based on the blasting parameters, loading quantity, and rock mechanical characteristics used in the field, the elevation effect of the numerical model of the underground powerhouse is established by using the dynamic finite element software. By comparing the numerical simulation and the on‐site monitoring of the elevation direction vibration velocity at the same location, it is found that the two have the same law, which verifies the reliability of the numerical calculation model. By changing the elevation and horizontal distances to select the measuring points in the numerical model, the propagation curve of the blasting vibration of the high side wall of the underground powerhouse in the elevation direction is obtained and the wave propagation phenomenon and the local elevation amplification effect of blasting vibration velocity in the side wall of the powerhouse are found. By means of changing the morphology characteristics of the rock anchor beam, a numerical calculation model of the rock anchor beam before casting is established, and the blasting vibration velocity in the elevation direction of the same measuring point as the original model is extracted. The analysis and comparison results show that the “whiplash effects” caused by the reflection superposition of the convex morphology characteristics of the rock anchor beam on the blast wave and the vibration response of the rock mass at the step part is the main factor for the elevation effect. The fluctuation phenomenon of the vibration velocity in the elevation direction is caused by the natural frequency and the main vibration mode of the high side walls, and the reflection superposition of the convex geomorphology characteristics of the rock anchor beam will aggravate this fluctuation phenomenon. Therefore, in the construction of deep underground powerhouses, attention should be paid to the blasting construction and support design of the rock anchor beam.

Blast protection in urban areas using protective plants

The increased threats by terroristic actions require the protection of urban areas. The protective potential of currently available protective systems is often recognizable, which may therefore raise the perceived threat. This is acceptable for temporary solutions but in the long-term contrary to the idea of a modern and open society. For permanent use, new solutions, which are not recognized as protective elements and deploy their protective potential inconspicuously, should be considered. Among them, there are elements of city furniture and landscape architecture. This article addresses theoretical, numerical, and experimental research towards protection capabilities of plants against blast. The research shows that plants of certain characteristics reduce the blast pressure by up to 60% compared to unimpeded blast wave propagation. These first studies pose specific questions that need to be answered in further research.

Shock Response Analysis of a Large LNG Storage Tank Under Blast Loads

Ensuring the safe operation of large LNG storage tank projects under blast loads is very important. First, using LS-DYNA software, numerical simulations of air blast wave propagation are studied with the ALE algorithm and fluid-solid coupling theory. A new corrected formula for the peak overpressure is proposed based on the numerical results, and its accuracy is verified by comparing the numerical results with the empirical formula and test results. Then, a finite element model of a large LNG storage tank is built, assuming that the explosion source is located 10 m away from both the ground and the tank wall. This model is used to analyse the overpressure and dynamic response of the outer concrete tank and to predict the TNT equivalent quantity that the tank can withstand. The results show that the tank wall facing the burst loads is in a more dangerous state and that the principal tensile stress increases approximately linearly with increasing TNT equivalent quantity. When the TNT equivalent quantity reaches 2.5 t, concrete element failure occurs on the centre facing the explosions, and the outer tank structure is damaged. The conclusions can provide a reference for the blast-resistant design of large LNG storage tanks.