Explosion Shock Wave Research Articles

A Numerical Study on the Blast Wave Distribution and Propagation Characteristics of Cylindrical Explosive in Motion

In order to study the overpressure distribution law of a shock wave under the dynamic explosion of a cylindrical charge and the influence of the charge speed on the overpressure distribution law, a trinitrotoluene (TNT) cylindrical bare charge was selected. Additionally, a numerical simulation of a cylindrical charge explosion under different motion speeds was carried out using the AUTODYN finite element software. The results showed that during the static explosion of a cylindrical charge, the shock wave propagates outward in the form of an ellipsoid, whereas under the dynamic explosion, the shock wave overpressure field is an irregular ellipsoid, and the shock wave overpressure zone shifts to the velocity direction. With an increase in the charge velocity, the peak value of the shock wave overpressure increases gradually in the moving direction. The simulation data were analyzed, revealing that the calculation model of the dynamic explosion shock wave overpressure field of a cylindrical charge with a scaled distance of 1 m·kg−1/3 ≤ R ¯ ≤ 1.5 m kg−1/3 can provide a reference basis for the study of dynamic explosion shock waves.

Research on the distribution characteristics of explosive shock waves at different altitudes

There are great differences in the distribution characteristics of shock waves produced by ammunition explosions at different altitudes. At present, there are many studies on plain explosion shock waves, but there are few studies on the distribution characteristics of plateau explosion shock waves, and there is still a lack of complete analysis and evaluation methods. This paper compares and analyzes shock wave overpressure data at different altitudes, obtains the attenuation effect of different altitudes on the shock wave propagation process and proposes a calculation formula for shock wave overpressure considering the effect of altitude. The data analysis results show that at the same TNT equivalent and the same distance from the measuring point, the shock wave overpressure at high altitude is lower than that at low altitude. With the increase in the explosion center distance of the measuring point, the peak attenuation rate of the shock wave overpressure at high altitudes is smaller than that at low altitudes, and the peak attenuation rate of the shock wave overpressure at high altitudes gradually intensifies with increasing proportional distance. The average error between the shock wave overpressure and measured shock wave overpressure in a high-altitude environment obtained by using the above calculation formula is 11.1389%. Therefore, this method can effectively predict explosion shock wave overpressure in plateau environments and provides an effective calculation method for practical engineering tests.

Hoop and axial plastic buckling modes of submerged cylindrical shells subjected to side-on underwater explosion shock wave

Cylindrical shells are widely used in marine structures from small-sized pipes to various immersed containers and large submarines. Dynamic plastic buckling of the shells could be caused by underwater explosion (UNEX) loads in industrial accidents or hostile attacks. Influential factors including non-dimensional hull shock factor reflecting the resilience of the material to shock intensity, slenderness ratio, localised ring stiffener and endcap are identified. Their impacts on the dynamic buckling modes are discussed relied on the finite element investigations. The results show that the global hoop and axial buckling modes are mainly determined by the hull shock factor and slenderness ratio, respectively. With the increase of hull shock factor, i) back-side buckling, ii) back- and front-side buckling with dominant buckles at the back-side, iii) back- and front-side buckling with dominant buckles at the front side, and iv) overall buckling with very large buckles at the front-side originating from the priority buckling modes can be observed in the circumferential direction. The competition between the front- and back-sides buckling is attributed to their different buckling mechanisms. The former one is caused by shock transmitted from the explosion source through the fluid, whereas the later one is due to striking of the structural hoop stress waves propagated from the front-side via the shell itself. Axial buckling modes consisted of primary and potential buckles alternating in the axial direction could be triggered for a large slenderness ratio, but be concealed by localised buckling modes for small slenderness ratio. The localised buckling modes are controlled by the ring-stiffener and endcap, because they alter the continuity of compression potential of shells.

Effects of underwater explosion depth on shock wave overpressure and energy

In this paper, the effects of the water depth on the overpressure (pressure difference between positive shock pressure and hydrostatic pressure) peak and energy of underwater explosion shock waves were analyzed. Two quantitative calculation models were established that accounted for the effect of the water depth, which have theoretical and practical engineering value. A simulated deepwater explosion tank test was first conducted to obtain experimental data of the overpressure peaks and energies of the explosion shock waves generated by 10 and 30 g trinitrotoluene (TNT) explosives in a simulated environment at water depths of 400, 500, and 600 m. A one-dimensional wedge-shaped Euler grid numerical model was established to simulate the underwater explosion using the Autodyn software. The simulation model was validated by the experimental data to prove its accuracy and rationality. Then, numerical simulations were carried out at 13 operating conditions with 30 g of TNT in a full water depth range of 0–5000 m. Based on the simulation data analysis, the calculation models of the overpressure peak and energy flow density of the underwater explosion shock wave were obtained, which contain water depth correction functions. The results show that both the overpressure peak and the shock wave energy decreased with increase in the water depth, but the reduction percentage of the overpressure peak with the water depth was very small. The overpressure peak and energy flow density of the shock wave agreed with the explosion similarity law at all fixed water depths. The proposed calculation models have practical engineering value and generalization ability.

Simulation Study of Gas Explosion Propagation Law in Coal Mining Face With Different Ventilation Modes

In ventilation working face, different ventilation way is one of the important factors affecting the propagation of gas explosion shock wave. In order to study the gas explosion shock wave propagation laws in coal mining faces with different ventilation methods, using Fluent simulation software, combined with pipeline gas explosion experiments and the actual situation of gas accumulation area explosion in the corner of 415 coal face in Chenjiashan coal mine, Shaanxi Province, and on the basis of building a three-dimensional mathematical and physical model, the gas explosion simulations under Y-type and W-type ventilation methods were carried out, respectively. The results are described as follows: (1) The attenuation trend of overpressure peak value of inlet roadway 1 and working face with Y-type ventilation conforms to the power function form. Intake airway 2 and return airway have the same peak overpressure attenuation trend, but the peak value of overpressure in return airway is generally 10.6% higher than that in intake airway 2, and its attenuation rate is a process from low to high and then to low. (2) The peak attenuation trend of overpressure in intake airways 1 and 2 with W-type ventilation conforms to the form of power function, and the peak attenuation trend of overpressure in return airway conforms to the form of exponential function. The peak value of overpressure decreases with the increase in the distance from the explosion source, and its attenuation rate decreases gradually. The research results have important theoretical significance for improving the prevention of gas explosion in coal mining face with different ventilation modes.

Mechanism of the traumatic brain injury induced by blast wave using the energy assessment method

Although blast-induced traumatic brain injury (b-TBI) is well recognized for its significance in the military population, the unique mechanisms of primary b-TBI remain undefined. The aim of the present study is to unveil the mechanism of the traumatic brain injury induced by the shock wave using the energy assessment method. First, the magnetic resonance images of the human head were processed to establish the finite element (FE) model of the human head including the skin, the skull, the brain and other structures. The simulation of the shock wave was implemented using the Coupled Eulerian-Lagrange (CEL) method, a fluid-solid coupling model of explosive shock wave-head. The coupled model was used to simulate the situations of head subjected to the frontal direction, the side direction and the rear direction by explosive shock wave. The predictions of the FE results were validated by comparing them with previous studies. Then, the degree of b-TBI in three different directions i.e., the frontal direction, the side direction and the rear direction, was assessed to investigate the influence of the direction of the shock wave on the b-TBI. Finally, the various energies including strain energy, kinetic energy, viscous energy and creep energy were extracted from the FE calculations for investigating the mechanism of b-TBI. The results showed that under the scenario of the shock wave, the brain injury was caused by the combined actions of acceleration of the head and the deformation of the skin& facial muscle tissues, the brain and the cerebrospinal fluid (CSF). In addition, it was also found that the dissipation capacity of the head was not sensitive to the impact direction. The present study provides important data and theoretical basis for the mechanism of b-TBI.

Interaction of Blast Waves with Multilayer Surfaces and Multiphase Media

The possibilities and methods of attenuation of blast waves when they are reflected on any limiting surface in terms of the peak pressure and momentum of the compression phase are of real practical interest. This interest stems from the need to eliminate or maximally mitigate the harmful effects of accidental and terrorist explosions. Porous materials are widely used in a variety of engineering structures due to their superior energy absorption capacity and other advantages in mechanical and physical properties. But when the porous material was used in protective structures to resist an explosive shock wave or high velocity impact, the protective function of the porous material was questionable. There are data indicating both a weakening and an increase in the explosive load on the protected object, depending on the structure of the porous material, the thickness of the protective layer, the duration of the positive phase of the blast wave pressure.

Simulation of the Deformation and Failure Characteristics of a Cylinder Shell under Internal Explosion

Under the load of an internal explosion shock wave, the failure of a cylindrical shell is the basis of safety evaluation and failure analysis of explosion vessel design. This paper carried out the explosion loading experiment of a cylindrical shell, and used the nonlinear dynamic finite element analysis program LS-DYNA for the dynamic response of the cylindrical shell along the directions of thickness and length, and analyzed the failure law of a cylindrical shell. The results showed that the deformation of the core section of the cylindrical shell was not different in the same specific distance, the strain decreased more slowly with the increase of thickness at the end of the explosion center, and the expansion failure process and fracture mode of metal shell under explosive load were affected by the material and structure size of the shell, as well as the characteristics and mode of the load. Based on the plastic theory, this paper discussed the evolution characteristics of the stress state during the expansion process of cylindrical shells under different explosion pressures, and analyzed the explosion pressure effect on the tensile fracture and shear fracture. The expansion failure experiment of a 20# steel-made cylindrical shell and the microscopic and metallographic analysis of the recovered debris were carried out.

Doom-roof steel tanks under external explosion: Dynamic responses and anti-explosion measures

Large-scale cylinder storage tank is a kind of typical thin shell space structure, which is widely used in the storage of petrochemical products such as LNG, LPG and so on. The dynamic responses and failure process for steel tank under external explosion shock wave are complex dynamic problems with strong instantaneity, strong non-linearity and strong coupling. In this paper, a coupled analysis model was developed for simulating the dynamic responses of tank under external ground explosion. Compared with experimental datas which were given in existing relevant studies, the validity for numerical model and accuracy for simulation results were verified. Dynamic response for typical cylindrical tank was obtained through coupled numerical simulation, and the influences of scaled distance and tank wall thickness were studied through parameter analysis. Based on the simplified model of explosion loading on tank, the difference of dynamic response between uncoupled model and coupled model was analyzed. The anti-explosion effect for different parameters of anti-explosion bands on tank under external explosion was finally compared. The results show that: 1) The lower two layers tank wall firstly appear inward concave deformation and local plastic state. With the shock wave propagating upward along tank wall, the concave deformation and plastic strain of the front surface of tank wall increase obviously, and the maximum deformation region moves up to the middle part of tank wall, while the maximum plastic region basically remains at the lower part of tank wall. 2) Both the changes of scaled distance and tank wall thickness have significant influences on the deformation and equivalent plastic strain for steel storage tank. The maximum equivalent plastic strain and fracture failure mode generally appears at the lower part of tank wall firstly. The increase of the tank wall thickness is an effective measure to reduce the deformation and plastic strain for tank, and strengthen the anti-explosion performance for tank. 3) Due to the obstacle effect of the anti-explosion bands, the maximum equivalent plastic strain region moves from the bottom part of tank wall to the middle and upper part of tank wall. The displacement and equivalent plastic strain for steel tank decrease with the increase of cross-section and spacing for anti-explosion bands, and the effect of the former (increase height only) is relatively better.

The Study on the Shock Wave Propagation Rule of a Gas Explosion in a Gas Compartment

Combined with the k-ε turbulence model of general application, a refined finite element model of a utility tunnel’s gas compartment filled with the methane/air mixture is developed. A series of analyses are made by using the powerful industry-leading computational fluid dynamics (CFD) software flame acceleration simulator (FLACS) to study the shock wave propagation rule in the gas compartment. The longitudinal and transversal distribution laws of the explosion shock wave are gained taking into consideration the spatial characteristics of the gas compartment. The influences of a few parameters, such as initial conditions and section size of the gas compartment, on the shock wave propagation rule are further discussed. The basic procedure for predicting the peak pressure of the blast wave is provided by considering the initial conditions and the gas compartment, and the corresponding injury effect of the explosion wave on the living beings is assessed. The investigation demonstrates that the peak pressure by the coupled effect between the initial conditions is significantly influenced, especially at the upper and lower gas explosion limits. The peak pressure increases gradually as the width or height increases, and both basically meet the linear relation. The proposed method can forecast the peak pressure of the explosion shock wave in the gas compartment accurately. According to the peak pressure longitudinal and transversal distributions of the blast wave, the peak pressure is far greater than the killing pressure threshold in the underground and closed space; consequently, it is not safe for the living beings in the gas compartment.

Influence of cavity structure on gas explosion characteristics in coal mine

Through theoretical analysis, experimental research and numerical simulation, the influence of cavity structure on explosion wave propagation is explored. The mathematical model of shock wave propagation in the cavity is established to verify the feasibility of cavity explosion suppression and isolation technique. The explosion shock wave and flame isolation experiments of eight different sizes of cavities were carried out by a self-built large gas explosion experimental system. The results show that the length and width of the cavity jointly affect the explosion shock wave isolation effect, and the flame isolation effect is more obviously affected by the width of the cavity. Through the analysis, it is suggested that the cavity with length-diameter ratio of 2.5, width-diameter ratio of 4 and height-diameter ratio of 1 should be used as the flameproof cavity. The propagation process of explosive shock wave in cavities with different sizes is explored by numerical simulation.

High-hardness polyurea coated steel plates subjected to combined loadings of shock wave and fragments

To investigate the effect of polyurea on the protective performance of a steel target plate under the combination of shock wave and fragments, the failure characteristics, damage process and micro mechanism of the polyurea coated steel plates with different coating methods under the combination of explosion shock waves and fragments were analyzed through experiments and numerical simulations. The results showed that single-sided coatings aggravated the damage of target plate when the coating thickness was 2 mm. While the polyurea thickness greater than 4 mm could significantly reduce the damage degree of the steel plate. When the polyurea was coated on the double sides, it would aggravate the damage, no matter how thick the polyurea was. Through microscopic research, it was found that the front coated polyurea was severely ablated by detonation products, which greatly reduce its energy absorption efficiency. The polyurea coated on the back underwent tensile fracture under the influence of tensile stress wave. The breaking of intramolecular hydrogen bond of polyurea was the key to the energy absorption of polyurea.

Research on image measurement of explosion shock wave based on high speed schlieren technology

Research on image measurement of explosion shock wave based on high speed schlieren technology

Simplified Algorithm Model for Explosion Shockwave Load in the Cabin

In order to obtain the shockwave load simplified algorithm model for the semiarmored projectile internal explosion in the cabin, this research made use of AUTODYN to provide a numerical modeling method for explosion in the cabin and verified the accuracy of the method via the experiment. Internal explosion simulation calculation was conducted on the operating condition numerical model with different cabin structural dimensions and different explosive loads. The cabin internal explosion space was divided into the noncorner central area, near-wall area, two-sided corner area, and three-sided corner area. Through regression of the abovementioned calculation results, an engineering model to calculate the shockwave load was obtained. It is hoped that the model can offer some references to the antiexplosion design for the ship cabin and for damage assessment of the internal explosion.

Cause analysis and damage mechanism of explosive destruction with case investigation involving LPG tank trailer

Identifying causations and failure analysis at the onset holds a key to ensure LPG (liquefied petroleum gas) tank trailer transport safety state and prevent similar failures. Current study presents an unexpected accident by LPG tank trailer, which triggered a massive LPG dispersion and destructive explosion. After the post-accidental scene reconstruction by computational approach, the occurrence of pressurized tank burst and continuous dispersion were detected as an active failure analysis. Macroscopic investigation of the explosion phenomenon involving LPG tank trailer suggested that the causation was responsible for vapor cloud explosion. Hazardous parameters regarding the LPG release, dispersion, explosion shock wave and thermal radiation were represented to identify the mechanisms of potential damages by obtaining at multi-directional area. The visual graphics of flammable gaseous mixtures dispersion showed that the ambient factors imposed great influence on explosive energy reserve in different areas, which were not in accordance with the actual accident scene. The results revealed that the reflected and disturbed effects significantly increased the shock wave, causing more severe structural damage with dense obstacles and elevated flame. A large amount of released gaseous mixtures accumulated, resulting in much higher thermal intensity formed by fireball. This study proposed a failure analysis and classifications of LPG tank trailer accident by explosive destruction integrated with damage mechanism, which contributes to improve the hazard identifications and emergency response under LPG transportation accident sequences.

Информационная технология анализа рисков для сосудов под давлением

An integral part of any production is to ensure industrial and natural safety. One of the potential solutions to such problems can be considered as modeling and visualization of emergency situations, as well as their analysis. The authors of the article propose to use geographic information system technologies in order to conduct primary risk assessment by simulating the propagation of an explosive shock wave in emergencies associated with the rupture of vessels under high pressure.

Propagation characteristics of the overpressure waves and flame fronts of methane explosions in complex pipeline networks

The propagation characteristics of the overpressure waves and flame fronts of methane explosions in complex pipe networks under realistic conditions were studied. A custom-designed experimental platform was used, the propagation characteristics of overpressure wave and flame wave in complex pipe network were characterized by overpressure attenuation coefficient and flame mutation coefficient. The results showed that the overpressure wave propagation characteristics in complex pipe networks were more complicated and disordered than those in straight or simple branched pipes. The overpressure wave attenuation and superposition occurred many times in the propagation process, the explosion shock wave attenuation in the beveled branch pipe was faster. When the flame wave passed through all the branch tubes, the flame wave velocity increased significantly. When the flame wave passed through the same tube at different times, the flame wave mutation coefficient was different, the change of flame wave temperature had a certain lag compared with the change of flame velocity, resulting in the peak of flame wave temperature and flame wave velocity appearing in different branch tubes. The experimentally obtained data were fit to functional relationships using nonlinear multiple regression analysis, and good agreement between the functional relationships and the data was obtained.

Influence of Roadway Cross-Section Shape on Gas Explosion Shock Wave Law in U-Type Ventilation Working Faces

In U-shaped ventilation working face, different tunnel section shapes are one of the important factors affecting the propagation of gas explosion shock wave. In order to study the propagation law of gas explosion shock wave in working face, the numerical simulation study was carried out by using Fluent simulation software combined with the actual situation of gas explosion in #415 working face of Chenjiashan Coal Mine in Shaanxi Province. By constructing a three-dimensional mathematical and physical model, a simulation study of the upper-corner gas explosion was carried out. The results are described as follows. (1) After the gas explosion shock wave propagates 40 m, the overpressure peak equidistant difference tends to be stable and attenuates and propagates in the form of a single shock wave. The study determines that the effective length of the U-shaped ventilation inlet/return tunnel is 40 m. (2) When the tunnel section is trapezoidal, the initial overpressure of the gas explosion shock wave propagating to the inlet/return airway is the highest, followed by rectangular and semicircular arches, but the internal overpressure attenuation trend of different cross-sectional shapes is the same. (3) The gas explosion shock wave propagates radially along the working face section during the working face propagation. The farther away the location is from the upper corner of the tunnel during a gas explosion with different cross-sectional shapes, the closer the cutoff overpressure peak is. The attenuation trend of overpressure with the propagation distance conforms to the power function law. The research results provide an important theoretical direction for the numerical simulation of gas explosions in coal mining faces.

The influence of sensor installation angle on explosive shock wave overpressure test

In the engineering measurement of explosion shock wave pressure, the installation method of shock wave pressure sensor is of great significance to accurately obtain shock wave pressure. Based on the actual shooting range explosion shock wave overpressure test program, this paper uses AUTODYN to establish a finite element numerical simulation model. The distance from the ground reflection pressure sensor to the explosion center is 3 m, 4 m, 5 m, and 6 m. The shock wave overpressure data in the range of 8° and 10° are acquired and analyzed. The analysis results show that the shock wave overpressure obtained when the sensor installation angle is absolute zero is the ideal value. When the sensor installation plate is within a certain range, the overpressure value of the explosion shock wave increases with the increase of the installation angle of the plate, and the installation angle of the sensor is positively correlated with the overpressure of the explosion shock wave.

Experimental research on the dynamic characteristics of underwater shock wave pressure sensor

With respect to the calibration of dynamic pressure measurement system under specific underwater explosion application environment, this paper has proposed an experimental calculation method for the dynamic characteristics of underwater shock water pressure sensor based on a preloaded water shock tube. This was done by analyzing the dynamic calibration principles of the preloaded water shock tube and studying the dynamic influencing factors pertaining to the sensor. Moreover, a dynamic calibration experiment for the sensor was also designed based on a comparative calibration method, through which a calculation method for the dynamic characteristics of underwater shock wave pressure sensor was acquired. The experimental results have proven that applying preloaded water shock tube can effectively acquire the dynamic characteristics of the pressure sensor, thereby providing a research framework for the dynamic calibration of underwater explosion shock wave pressure sensor.