Propagation Law Of Shock Wave Research Articles

Dynamic response of aluminum-graphene layered nanocomposites under shock compression and release based on atomistic simulations

To understand the role of aluminum-graphene (Al-Gr) interface, molecular dynamics simulations have been conducted to investigate the dynamic response of Al-Gr layered nanocomposites. The propagation law of shock waves is revealed and the dislocation nucleation at Al-Gr interface may dominate the plastic deformation mechanism at low impact velocities, which results in the propagation of stepped waveforms. In other words, Gr facilitates dislocation nucleation and its full development in each Al layer. At high impact velocities, Gr can hinder the forward propagation of BCC Al, although Gr can promote BCC nucleation. During shock release, Gr reduces the spall strength of the Al-Gr layered nanocomposites, and then the fracture is dominated by interface fracture, exhibiting single-layer or multi-layer delamination. Gr is found to undergo bending and folding, but Gr remains intact owing to its exceptionally high tensile strength and resistance to high temperatures. With the development of voids and cracks near the Al-Gr interface, the Al layer undergoes significant geometric deformation without internal fragmentation..

Design of shock wave attenuation effects on multi-impedance-matched laminated composites

To improve the protective performance of composite armor materials, three types of laminated composites with different arrangements were designed by the principle of impedance matching. The impedance combination schemes used in this work were high impedance→low impedance (type I), low impedance→high impedance (type II), and high and low impedance (type III). The microstructures and properties of the test samples prepared in a vacuum hot-pressing furnace were investigated by micro-indentation and dynamic impact experiments. According to the propagation theory of one-dimensional elastic waves in multilayered media, the propagation law of shock waves in the as-prepared laminated composites was examined. Micro-indentation test results revealed that the hardness of the Fe2Al5 intermetallic compound formed by the reaction of Al and 304 SS was the highest and ranged from 917.5 HV to 1026.3 HV. The type II layered composite had the highest compressive strength (1139 MPa) followed by the type I composite and the type III composite. The type III composite manifested the highest energy absorption efficiency (73%) followed by the type II layered composite and the type I composite.

Experimental and numerical simulation of the propagation law of shock waves in corrugated steel-lined tunnels

Corrugated steel support structures are widely used in engineering tunnels owing to their rapid construction and high bearing performance, allowing for the complex propagation of shock waves. To clarify the propagation law of shock waves in a corrugated steel tunnel with interior lining, a 30-m-long straight tunnel was built to explore the propagation of an explosion shock wave, and three different tunnel inner walls were designed, namely, a concrete inner wall and two types of corrugated steel linings. Based on the data on the monitored shock wave, the propagation law of shock waves in the tunnel was obtained, and the influence of corrugated steel linings on the shock waves was analyzed. A finite element model of the channel was established to verify the results of experiment and determine the model and related parameters. This model was also used to perform a numerical simulation of explosion shock wave propagation in corrugated steel-lined tunnels of various sizes. Based on the experimental and numerical simulation results, a prediction model of shock wave overpressure in corrugated steel-lined tunnels was obtained. Research showed that the shock-wave energy of wavefronts near walls was diverted, the formation and propagation of waves reflected from walls was affected by corrugated steel linings, which effectively improved the attenuation efficiency of shock waves in tunnels.

Application of a Simulation Method for the Shock Wave Propagation Law of Gas Explosion.

Gas explosion is one of the main causes of casualties in coal mines. Studying the propagation law of shock wave of mine gas explosion can reduce the economic loss and personnel injury caused by mine gas explosion. To solve the difficulty in the research of shock wave propagation of gas explosion in the mine scale, the segmented relay simulation method of shock wave propagation of gas explosion in a coal mine was put forward, the related key problems were studied, and the results were successfully applied in Yangchangwan No. 2 Mine. The results show the following: (1) When the length of the forked roadway exceeds 50 m, the length of the forked roadway has little effect on the shock wave overpressure in the main roadway. When the length of the forked roadway is short, the closure of the forked roadway has a great influence on the change curve of the shock wave overpressure in the main roadway. Therefore, the length of the bifurcation roadway should not be less than 50 m in numerical simulation. (2) The angle of the bifurcated roadway has a great influence on the shock wave propagation of explosion in the main roadway. With the increase in the angle of the bifurcated roadway, the overpressure in the main roadway tends to increase at first and then decrease, and the peak overpressure is the highest when the angle of the bifurcated roadway is 90°. (3) The influence range of the roadway pressure-outlet boundary is about 5 m, and the dynamic parameter monitoring point should be set at about 10 m away from the pressure outlet; dynamic boundary monitoring parameters should include static pressure, dynamic pressure, and temperature. (4) When the gas explosion occurs in the heading face, the shock wave will cause great damage to the adjacent heading face. When the shock wave reaches the head-on and upper corner of the heading face, it will be reflected violently, which will cause the local overpressure to rise obviously. The peak overpressure and gas accumulation length conform to the logarithmic function.

Numerical simulations of trajectories of shock wave triple points in near-ground explosions of TNT charges

To accurately predict the locations and trajectories of shock wave triple points in near-ground explosions, this study determined the propagation law of shock waves after the initiation of a detonator using a schlieren system. Moreover, it established a numerical simulation model using the Autodyn software and verified the accuracy of the model through a detonator explosion experiment. The propagation law of shock waves of TNT charges (1, 10 ​kg and 100 ​kg) at different heights of burst(0.5, 1.0, 1.5, 2.0 ​m,and 2.5 ​m) was studied through numerical simulations, and the triple point trajectories were fitted to an empirical formula. The results show that the maximum simulation error relative to the schlieren images of detonator explosions did not exceed 4 ​mm. As the scaled height of burst decreased, the positions of generated triple points were closer to the vertical projection of the explosion center and rose faster. As the scaled distance increased, the scaled height of triple points rose exponentially. The average error of triple point trajectories between the values predicted in this study and the experimental values was 4.1%, indicating that the accuracy of the fitted formula is acceptable. This study revealed the overpressure distribution law of shock waves and will provide a reference for shock wave overpressure measurements and explosion protection.

Plane shock wave propagation in partially saturated soil

Considered that the gas content of partially saturated soil would decrease under a shock load, which would cause volumetric plastic deformation, Lyakhov's constitutive model is improved. The P-α state equation is used to describe the volume compression relationship of partially saturated soil. Numerical and experimental results are compared to validate the material model. The peak stress and duration of shock wave are crucial to study the dynamic response of underground structures. Considered the saturation of partially saturated soils under natural conditions increases with depth and both peak stress and duration change when shock waves propagate in inhomogeneous media, several partially saturated soil models with linearly decreasing air content in the depth direction are developed. The propagation law of shock waves with various peak stresses and durations in partially saturated soils is studied. The results show that the peak stress caused by the incident load in partially saturated soil first decreases and then increases under incident loads with a shorter duration, and it increases monotonically under incident loads with a longer duration. The rate of change in the incident peak stress is proportional to the air content at the top of the partially saturated soil. The peak free-field stress reaches its maximum, which is 2.2 to 5.5 times the peak stress of the incident load, in fully saturated soil. Long-duration incident loads such as nuclear explosions are more threatening to underground structures than short-duration incident loads. Underground structures buried in fully saturated soil or below fully saturated soil with higher air contents above are more at risk than underground structures buried in partially saturated soil with smaller air contents.

Array model of shock pressure sensor for shooting point detection

The array model of double-T shock pressure sensor is established. Shock wave is produced by a supersonic object in the air. Pressure is produced in the process of shock wave transmission. Different shock pressure sensors have different time to receive the pressure signal. In this paper, the shooting point calculation model and the finite element model of the double T-shaped array method are established. The simulation experiment is carried out. The law of shock wave propagation is verified. The model can be used to calculate the coordinates of shooting point quickly. This method is suitable for small angle oblique fire location problem, and improves the detection accuracy of shooting point.

Experimental study on propagation law of shock wave and airflow induced by coal and gas outburst in mine ventilation network

Coal and gas outburst seriously threatens the safety of underground coal mining. After the outburst, it will not only cause harm in the near-field outburst roadway but may also have a strong impact on the far-field ventilation network connected to the outburst roadway, expanding the impact of the disaster. In order to define the propagation law of shock wave and airflow induced by the outburst and its influence on the far-field ventilation network, the coal and gas outburst experimental system was used to carry out an experimental study under different air current and local resistance conditions in this paper. The results show that, under different air current states, the first overpressure peak increases with an increase of outburst pressure and decreases with an increase of propagation distance. Compared with the propagation characteristics in a windless roadway, the first overpressure peak and attenuation coefficient of shock wave propagating downwind are smaller, whereas opposite in upwind state. The local resistance enhances the impact and disturbance ahead of it and weakens that after it. When shock airflow propagates downwind, the increase of shock airflow velocity is approximately equal to the original airflow velocity in the roadway, whereas the airflow direction may reverse when the shock airflow propagates upwind. This paper provides some references to prevent the impact expansion of coal and gas outburst, which are of great significance for the optimization of ventilation network and emergency management.

Static Explosion Field Reconstruction Based on the Improved Biharmonic Spline Interpolation

To obtain the peak pressure distribution of explosion field near the ground, an improved reconstruction method for interpolation of blast overpressure data from the finite measuring points was studied. According to the peak attenuation law of shock wave on the propagation path and the attenuation characteristic of the wave front after passing through the measured points, the polynomial fitting function of peak attenuation of shock wave near the ground is constructed by using the least square method. Using the peak attenuation polynomial of shock wave constrain the radial interpolation of biharmonic spline surface interpolation algorithm (BSSIA) to realize the interpolation conforming the propagation law of shock wave and ensure the interpolation convergence. The root-mean-squared error (RMSE) and the maximum relative error (MRE) before and after the improvement were computed by comparing the peaks with empirical formula data. The improvement is evident as the RMSE decreased from 14.12kPa to 0.22kPa and the MRE decreased from 23.91% to 0.37%. The peak reconstructed by the improved biharmonic spline surface interpolation algorithm (IBSSIA) and BSSIA with test data, the overpressure peak distribution obtained by IBSSIA is in good agreement with empirical result and consistent with the explosion image.

Experimental Study on Thermal Aging Performance of an RDX Based Booster

YC-1 booster (96.5% RDX, 3% F2641 and 0.5% graphite) was selected as the research object. Accelerated aging of YC-1 was carried out by 71°C thermal aging tests. The size changes of samples before and after thermal aging were measured. The initiation ability and shock sensitivity of the samples before and after accelerated aging were tested by steel compression test and SSGT small gap test. Through the establishment of equal proportion impact dynamics calculation model, the propagation law of shock wave generated by the explosion of A-= 9 \* ROMANIX-= 1 \* ROMANI was calculated. Test and calculation results show that: The diameter and height of samples increase with the increase of aging time. There was no significant change in the initiation ability of the samples, and the shock wave sensitivity increases first and then decreases with the increase of thermal aging time. The critical thickness of the gap corresponding to the samples aged 0 day, 4days, 19 days, 38 days and 76 days was 6.9mm, 7.0mm, 7.5mm, 8.1mm and 7.8mm, respectively. The corresponding shock wave pressure (without considering the interface reflection) in the gap was 2.91GPa, 2.85 GPa, 2.60 GPa, 2.40 GPa and 2.50 GPa respectively.

A Novel Arc-length Numerical Method for Shock Interruption Problems

Accurately tracking the propagation process of a wave front is important for studying the propagation law of shock waves. In this study, a novel arc-length numerical algorithm to effectively calculate the interruption of shock waves is proposed, and a systematic theoretical analysis and application of this research are conducted. First, the arc-length numerical method is proposed based on the hyperbolic conservation model equation, and the basic concept of the arc-length numerical method of hyperbolic problems is provided. Then, an introduction method for arc-length in multidimensional space is described from the perspective of tensor analysis, and the mathematical model of shock wave propagation problems in arc-length space is established. The discrete solution of the spatial mathematical model of arc length is given, and control and smoothing factors are added to ensure shock wave propagation without oscillation. Finally, the numerical calculation of the Lax and double Mach reflection problems shows that the arc-length numerical algorithm can be widely used as a new calculation method for shock interruption problems.

Bonding mechanism of explosive compaction–welding sintering

Correlation theories of explosive compaction–welding sintering are introduced, and a method for calculating the pressure required for explosive compaction–welding is provided. A macroscopic bonding mechanism study involving a flying-plate loading experiment reveals that the incident angle of a shockwave plays an important role in explosive compaction–welding, and the propagation law of shockwaves in powder layers is numerically analyzed using the AUTODYN-2D software. In the microscopic bonding mechanism study, the microscopic bonding modes of explosive compaction–welding are investigated with a Cu wire coating and Cu substrate. The smoothed-particle hydrodynamics numerical simulation method is used to simulate the void-closure process between the Cu wire and Cu substrate under specific pressures. By comparing the results of the numerical simulation and experiment, the micro-bonding modes of friction welding, explosive welding, jet injection, and liquid sintering are determined. The effect of diffusion sintering is studied, and the poor bonding areas are eliminated after diffusion sintering. The element diffusion between the coating and substrate is observed to ensure the existence of diffusion welding.

Numerical simulation damage analysis of pipe-cement-rock combination due to the underwater explosion

Electrical explosion of wire (EEW) has been used in the petroleum industry to improve oil recovery because it can generate a controllable and stable shock wave. The pipe-cement-rock combination model has been established to avoid the destruction of integrity between the casing pipe and cement sheath while it is treating the formation to increase oil and gas recovery. The propagation law of shock wave in the combination is simulated by nonlinear dynamics analysis code AUTODYN. What is more, the damage of combination caused by a single explosion and multiple explosions is also studied. The results show that the shock wave attenuates greatly through the casing pipe and cement sheath, but the shock wave propagating in a perforation hole can keep higher pressure, and the multiple explosions will cause cumulative damage to the combination.

Numerical Study on the Propagation Law of Shock Wave in Turning Tunnel

To study the propagation law of the shock wave in turning tunnel, the propagation process of shock wave in underground turning tunnels of 15°, 30°, 45°, 60°, 75° and 90° was simulated based on ANSYS/LS-DYNA. Results show that at the turning corner, the overpressure on the outside wall is 2 times that on the inside wall. According to the overpressure ratio criterion, the length of the turbulent zone is no more than 3.2 times the equivalent diameter of the tunnel. With the increase of the turning angle, the attenuation coefficient of shock wave decreases gradually, which indicates that the overpressure attenuation becomes less obvious. The results can provide an important reference for the protection design of the turning tunnel.

On the dynamic compression of cellular materials with local structural softening

Analytical and numerical analyses are carried out in order to reveal the importance of the cellular materials topology for their dynamic compaction. The aim is to distinguish between the deformation and energy absorption mechanisms of materials which exhibit local structural softening, such as out-of-plane loaded honeycomb, and materials with local structural hardening (foam). It is shown that the dynamic out-of-plane compaction of honeycombs does not obey the law of shock wave propagation and a new phenomenological model of the velocity attenuation is proposed. It is revealed that the absorbed energy by the honeycomb is proportional to the area under the dynamic stress-strain curve, which is defined by the foil material properties, in contrast to the shock-wave propagation model where the absorbed energy is proportional to the area under the shock chord. Comparisons with the predictions of the Rigid Perfectly-Plastic Locking (RPPL) model, which approximates well the average quasi-static stress-strain characteristic of a honeycomb, are discussed. Special attention is given to the effects of neglecting the honeycomb topology on their response to impact loading.Finite element simulations are carried out to verify the proposed theoretical model revealing the major factors which influence the dynamic response of out-of-plane loaded honeycombs to high velocity impact.

A Study of Polycrystalline Silicon Damage Features Based on Nanosecond Pulse Laser Irradiation with Different Wavelength Effects.

Based on PVDF (piezoelectric sensing techniques), this paper attempts to study the propagation law of shock waves in brittle materials during the process of three-wavelength laser irradiation of polysilicon, and discusses the formation mechanism of thermal shock failure. The experimental results show that the vapor pressure effect and the plasma pressure effect in the process of pulsed laser irradiation lead to the splashing of high temperature and high density melt. With the decrease of the laser wavelength, the laser breakdown threshold decreases and the shock wave is weakened. Because of the pressure effect of the laser shock, the brittle fracture zone is at the edge of the irradiated area. The surface tension gradient and surface shear wave caused by the surface wave are the result of coherent coupling between optical and thermodynamics. The average propagation velocity of laser shock wave in polysilicon is 8.47 × 103 m/s, and the experiment has reached the conclusion that the laser shock wave pressure peak exponentially distributes attenuation in the polysilicon.

Propagation law of shock waves in single layer spherical lattice shell under internal explosion

Using software of finite element analysis LS-DYNA, in this paper we performed numerical simulation on the propagation law of shock waves in single layer spherical lattice shell under the effect of internal explosion, obtained the laws of propagation, reflection, convergence and peak appeared of shock waves, concluded that the damage of enclosed structure is closely related to, initial overpressure peak, and partial secondary overpressure peak, analyzed the influences of explosive quantity, explosion center height, and explosive eccentric position on the propagation law of shock waves. Based on the results of numerical simulation, we concluded joint area between lattice shell top and wall shell is the key location for explosion venting and pointed out the calculation formula of overpressure peak on structure surface of higher fitting precision is feasible.

Experimental Study on Bubble Curtain Technology Applied in Underwater Blasting Damping

With the further development of urban construction, engineering blasting has had a wide range of applications. However, its application environment has become more and more complex relatively. Underwater blasting, one of the applications of engineering blasting, has been increasingly used in construction of subsea tunnel and immersed tube in recent years though it has a complex influence on surroundings in operation. For the study of shock wave absorption technology of underwater blasting, this paper analyses the effectiveness of bubble curtain shielding technology used in the underwater explosion by field experiment. The test result shows that intensity of underwater shock wave approximately reduced by 80% after passing through the bubble curtain, which indicates that the bubble curtain can effectively reduce the shock wave pressure in water; vibration caused by shock wave in water approximately reduced by 20% after passing through the bubble curtain, which reflects propagation law of shock wave has changed due to the effect of the curtain.

Propagation law of shock waves and gas flow in cross roadway caused by coal and gas outburst

In order to study the propagation law of shock waves and gas flow during coal and gas outburst, we analyzed the formation process of outburst shock waves and gas flow and established the numerical simulation models of the roadways with 45° intersection and 135° intersection to simulate the propagation of outburst gas flow and the process of gas transport. Based on the analysis of the simulation results, we obtained the qualitative and quantitative conclusions on the characteristics and patterns of propagation and attenuation of outburst shock waves and gas flow. With the experimental models, we investigated the outburst shock waves and gas flow in the roadways with the similar structures to the simulated ones. According to the simulation results, when the angle between the driving roadway and the adjacent roadway increased, the sudden pressure variation range in adjacent roadway and the influencing scope of gas flow increased and the sudden pressure variation duration decreased. The intersection between the driving roadway and the adjacent roadway has no effect on airflow reversal induced by the shock waves and gas flow.

Numerical Simulation of Explosion in a Confined Box-Shaped Structure

In order to study the propagation law of shock wave and blast load distribution when an interior explosion occur in a box structure, a numerical simulation of an interior explosion within a box-shaped structure is presented in this paper using LS-DYNA. Overpressure-time history curve of the blast load at the measured points is obtained by numerical simulation, and compared with the experimental results. Numerical simulation results and experimental results are in good agreement. The results show that the blast wave reflected and superimposed many times in the box-shaped structure. When TNT is located in the center of the box-shaped structure, the center and the corner of the wall suffered the maximum overpressure.