2014 Vol. 34, No. 2
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2014, 34(2): 129-136.
doi: 10.11883/1001-1455(2014)02-0129-08
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Abstract:
Aimed to the laser-driven flyer plate technique, laser-driven flyer experiments were conducted by using single pulsed laser beams at 1 064nm, of 15ns duration and up to 2Jenergy to explore the influences of the laser energy profiles as well as the mechanical properties of the metal foils on the velocities and integrities of the flyers.The experimental results indicate that the laser beams with "top hat" energy profiles are key and important base to launch the flyers with good qualities.There exists a good matching among the adhesion of the foil to the glass substrate, the shear strength and tenacity of the foil, for obtaining a high-velocity and good-integrity flyer.By using the combined flyer target with a thin layer of chromium sandwiched between the aluminum foil and the glass substrate, the aluminum flyers with 1mm in diameter and 3μm in thickness were accelerated to 8km/s, and the experimental repeatabilities were good.
Aimed to the laser-driven flyer plate technique, laser-driven flyer experiments were conducted by using single pulsed laser beams at 1 064nm, of 15ns duration and up to 2Jenergy to explore the influences of the laser energy profiles as well as the mechanical properties of the metal foils on the velocities and integrities of the flyers.The experimental results indicate that the laser beams with "top hat" energy profiles are key and important base to launch the flyers with good qualities.There exists a good matching among the adhesion of the foil to the glass substrate, the shear strength and tenacity of the foil, for obtaining a high-velocity and good-integrity flyer.By using the combined flyer target with a thin layer of chromium sandwiched between the aluminum foil and the glass substrate, the aluminum flyers with 1mm in diameter and 3μm in thickness were accelerated to 8km/s, and the experimental repeatabilities were good.
2014, 34(2): 137-144.
doi: 10.11883/1001-1455(2014)02-0137-08
Abstract:
By choosing naked cylindrical 75-g-TNT charges as explosion sources, impact experiments were carried out on steel cylindrical shells with the wall thickness of 2.75mm and the outer diameter of 100mm.The damage characteristics of the shells were obtained under different explosion conditions.The experimental results show that subjected to non-contact explosion, the cylindrical shell wall facing explosion deforms in a dish-shaped pit and the whole buckling deformation will occur along the axis of the cylindrical shell direction.The damage of the cylindrical shell is more serious when the shell-to-charge distance is bigger or the axis of the charge is perpendicular to the axis of the cylindrical shell.However, the crevasse and fragment will occur under the conditions of contact explosion.By means of LS-DYNA, the nonlinear dynamic response processes of the cylindrical shells subjected to explosion loading were numerically simulated with the Lagrangian-Eulerian coupling method.The deformation processes of the shell walls were described as well as the displacement-time and velocitytime curves of the impact points.The numerical simulation results are in good agreement with the experimental data.And based on the numerical simulations, the critical shell-to-charge distance was determined for estimating the rupture of the shell wall.
By choosing naked cylindrical 75-g-TNT charges as explosion sources, impact experiments were carried out on steel cylindrical shells with the wall thickness of 2.75mm and the outer diameter of 100mm.The damage characteristics of the shells were obtained under different explosion conditions.The experimental results show that subjected to non-contact explosion, the cylindrical shell wall facing explosion deforms in a dish-shaped pit and the whole buckling deformation will occur along the axis of the cylindrical shell direction.The damage of the cylindrical shell is more serious when the shell-to-charge distance is bigger or the axis of the charge is perpendicular to the axis of the cylindrical shell.However, the crevasse and fragment will occur under the conditions of contact explosion.By means of LS-DYNA, the nonlinear dynamic response processes of the cylindrical shells subjected to explosion loading were numerically simulated with the Lagrangian-Eulerian coupling method.The deformation processes of the shell walls were described as well as the displacement-time and velocitytime curves of the impact points.The numerical simulation results are in good agreement with the experimental data.And based on the numerical simulations, the critical shell-to-charge distance was determined for estimating the rupture of the shell wall.
2014, 34(2): 145-152.
doi: 10.11883/1001-1455(2014)02-0145-08
Abstract:
By considering the action of blasting wave, explosion-induced gas and initial gas pressure as well as geo-stress endured by coal seam simultaneously, the deep-hole blasting in low-permeability high-gas-content coal seams under different geo-stresses were numerically simulated by using the FLAC3Dcode.And the simulated results were compared with the laboratory model test and other related field studies on the permeability improvement of the low-permeability coal seams.The comparable analysis indicates that the geo-stress can dramatically inhibit the extension of the blast-induced cracks in the coal seams, especially for the deeply-buried coal seams.Though the radius of the blasting crack zones linearly decreases with the increasing of geo-stress, the blasting technique can also be adapted to enhance the permeability of the deeply-buried low-permeability coal seams.And the direction of the maximum geo-stress can affect the extension direction of the blast-induced cracks in some degree.Therefore, in a practical blasting engineering, the spatial location of the blast holes should be determined according to the state of the geo-stress endured by the coal seam.
By considering the action of blasting wave, explosion-induced gas and initial gas pressure as well as geo-stress endured by coal seam simultaneously, the deep-hole blasting in low-permeability high-gas-content coal seams under different geo-stresses were numerically simulated by using the FLAC3Dcode.And the simulated results were compared with the laboratory model test and other related field studies on the permeability improvement of the low-permeability coal seams.The comparable analysis indicates that the geo-stress can dramatically inhibit the extension of the blast-induced cracks in the coal seams, especially for the deeply-buried coal seams.Though the radius of the blasting crack zones linearly decreases with the increasing of geo-stress, the blasting technique can also be adapted to enhance the permeability of the deeply-buried low-permeability coal seams.And the direction of the maximum geo-stress can affect the extension direction of the blast-induced cracks in some degree.Therefore, in a practical blasting engineering, the spatial location of the blast holes should be determined according to the state of the geo-stress endured by the coal seam.
2014, 34(2): 153-160.
doi: 10.11883/1001-1455(2014)02-0153-08
Abstract:
Based on the field testing of the blasting vibration on a large-span project of the underground diversion tunnel in Xiluodu, which locates in the southwest of China, with middle geostress, the dynamic responses of the surrounding rock during the blasting excavation were calculated by combining LS-DYNA.The peak particle vibration velocity and the maximum tensile stress were used as the safety criterions to confirm the range of blasting damage, respectively.The calculation results indicates that the peak particle vibration velocity and the maximum tensile stress both appear in the middle of the sidewall in the blasting process, therefore the most dangerous area in the blasting process lies in the middle of the sidewall.The statistical relationship between the peak particle vibrating velocity and the maximum tensile stress in the middle of the sidewall was obtained by the numerical matching method, and the correlation coefficient of the peak particle vibrating velocity and the maximum tensile stress was tested.According to the statistical relationship between the stress and the vibrating velocity, the critical peak particle vibration velocity was put forward for controlling the damage to underground tunnel rock.
Based on the field testing of the blasting vibration on a large-span project of the underground diversion tunnel in Xiluodu, which locates in the southwest of China, with middle geostress, the dynamic responses of the surrounding rock during the blasting excavation were calculated by combining LS-DYNA.The peak particle vibration velocity and the maximum tensile stress were used as the safety criterions to confirm the range of blasting damage, respectively.The calculation results indicates that the peak particle vibration velocity and the maximum tensile stress both appear in the middle of the sidewall in the blasting process, therefore the most dangerous area in the blasting process lies in the middle of the sidewall.The statistical relationship between the peak particle vibrating velocity and the maximum tensile stress in the middle of the sidewall was obtained by the numerical matching method, and the correlation coefficient of the peak particle vibrating velocity and the maximum tensile stress was tested.According to the statistical relationship between the stress and the vibrating velocity, the critical peak particle vibration velocity was put forward for controlling the damage to underground tunnel rock.
2014, 34(2): 161-166.
doi: 10.11883/1001-1455(2014)02-0161-06
Abstract:
The minimum ignition energies of flake aluminum dust-air mixtures with different mass concentrations were tested in a 1.28-L MIKE3tube.According to the logistic regression model based on statistical analysis, the minimum ignition energy of the dust cloud was presented by the probability of ignition success.And the ignition probability-energy curves of the flake aluminum dust with different mass concentrations were calculated by means of the SPSS statistical analysis software.The investigated results display that as the mass concentration of the aluminum dust in the mixture increases, the minimum ignition energy first decreases quickly and then keep in a certain energy range.And the explosion sensitivity of the flake aluminum is higher than ordinary spherical one.Compared with the results calculated by other standard methods, the minimum ignition energy presented by the probability of ignition success is more consistent with the engineering test.
The minimum ignition energies of flake aluminum dust-air mixtures with different mass concentrations were tested in a 1.28-L MIKE3tube.According to the logistic regression model based on statistical analysis, the minimum ignition energy of the dust cloud was presented by the probability of ignition success.And the ignition probability-energy curves of the flake aluminum dust with different mass concentrations were calculated by means of the SPSS statistical analysis software.The investigated results display that as the mass concentration of the aluminum dust in the mixture increases, the minimum ignition energy first decreases quickly and then keep in a certain energy range.And the explosion sensitivity of the flake aluminum is higher than ordinary spherical one.Compared with the results calculated by other standard methods, the minimum ignition energy presented by the probability of ignition success is more consistent with the engineering test.
2014, 34(2): 167-173.
doi: 10.11883/1001-1455(2014)02-0167-07
Abstract:
By considering the particle size, location in random distribution and the composite content, a three-dimensional computation model was developed for explosive particles in free deposition.The pressing process of the explosive particles from free deposition to molded explosives was numerically simulated by using the non-linear finite element method.Based on the above, the meso-structural models of PBXs(HMX+TATB+Estane)were established.Thereby, numerical simulations were conducted to analyze the shock-to-ignition processes of the PBXs with different compositions in the meso-structural level.In the above numerical simulations, the thermo-mechanical coupling effect and the self-sustained thermal reaction within the PBXs were taken into account.The influences of the composition contents on the shock-to-ignition performances of the PBXs were discussed.The simulated results show that the composite explosives containing HMX and TATB become less sensitive as the TATB content in them increases.
By considering the particle size, location in random distribution and the composite content, a three-dimensional computation model was developed for explosive particles in free deposition.The pressing process of the explosive particles from free deposition to molded explosives was numerically simulated by using the non-linear finite element method.Based on the above, the meso-structural models of PBXs(HMX+TATB+Estane)were established.Thereby, numerical simulations were conducted to analyze the shock-to-ignition processes of the PBXs with different compositions in the meso-structural level.In the above numerical simulations, the thermo-mechanical coupling effect and the self-sustained thermal reaction within the PBXs were taken into account.The influences of the composition contents on the shock-to-ignition performances of the PBXs were discussed.The simulated results show that the composite explosives containing HMX and TATB become less sensitive as the TATB content in them increases.
2014, 34(2): 174-180.
doi: 10.11883/1001-1455(2014)02-0174-07
Abstract:
Experimental investigations and analysis were carried out on the vertical water-entry of the spheres.The development process of the cavities induced by the vertical water-entry of the spheres was discussed including the formation, open, closure and collapse of the cavities.The influences of the water-entry velocities and surface conditions of the spheres on the cavities were experimentally obtained.And the displacements, velocities, accelerations and drag coefficients of the spheres during the water entry were analyzed.The investigated results show that the motion parameters of the spheres present highly nonlinear characteristics.And there are obvious fluctuations of the motion parameters and the drag coefficients during the closed-cavity phase if the water-entry velocities are high.
Experimental investigations and analysis were carried out on the vertical water-entry of the spheres.The development process of the cavities induced by the vertical water-entry of the spheres was discussed including the formation, open, closure and collapse of the cavities.The influences of the water-entry velocities and surface conditions of the spheres on the cavities were experimentally obtained.And the displacements, velocities, accelerations and drag coefficients of the spheres during the water entry were analyzed.The investigated results show that the motion parameters of the spheres present highly nonlinear characteristics.And there are obvious fluctuations of the motion parameters and the drag coefficients during the closed-cavity phase if the water-entry velocities are high.
2014, 34(2): 181-187.
doi: 10.11883/1001-1455(2014)02-0181-07
Abstract:
A finite element model was developed for tetrachiral honeycombs.By using the developed model, numerical simulations were conducted to explore the deformation modes and energy absorption properties of the tetrachiral honeycombs subjected to different impact velocities.And the corresponding numerical simulations were carried out on hexagonal honeycombs by applying the existent model.The deformation mode diagrams and the dynamic response curves for two kinds of honeycombs were obtained.At low impact velocities, the deformation of tetrachiral honeycombs is of"Z"mode.At high impact velocities, "I"deformation mode is observed in tetrachiral honeycombs when crushing, which is similar to traditional honeycombs.And a transitional deformation mode is present in tetrachiral honeycombs subjected to moderate impact velocities.As the impact velocity increases, the localized bands transit from the fixed end to the impact end and the tetrachiral honeycombs display higher energy absorption capacities.When the velocity is low or moderate, the auxetic honeycombs display the unique shrinkage under dynamic compression.
A finite element model was developed for tetrachiral honeycombs.By using the developed model, numerical simulations were conducted to explore the deformation modes and energy absorption properties of the tetrachiral honeycombs subjected to different impact velocities.And the corresponding numerical simulations were carried out on hexagonal honeycombs by applying the existent model.The deformation mode diagrams and the dynamic response curves for two kinds of honeycombs were obtained.At low impact velocities, the deformation of tetrachiral honeycombs is of"Z"mode.At high impact velocities, "I"deformation mode is observed in tetrachiral honeycombs when crushing, which is similar to traditional honeycombs.And a transitional deformation mode is present in tetrachiral honeycombs subjected to moderate impact velocities.As the impact velocity increases, the localized bands transit from the fixed end to the impact end and the tetrachiral honeycombs display higher energy absorption capacities.When the velocity is low or moderate, the auxetic honeycombs display the unique shrinkage under dynamic compression.
2014, 34(2): 188-194.
doi: 10.11883/1001-1455(2014)02-0188-07
Abstract:
The initial thermal decomposition pathways of the supercell structures of ε, β and γ modifications at different temperatures were studied by molecular dynamics simulations, using the ReaxFF force field, the NPT and NVT ensembles and the Berendsen methods.The results show that the initial pathway of different CL-20polymorphs is only the N-NO2dissociation to forming·NO2radical fragments, and the main thermal decomposition products are N2, H2O, CO, CO2, NO2, NO3, HNO2, HNO3, N2O5, N2O2and NO.The reaction rate constants of main products with the same modification increase with the increasing of temperature.
The initial thermal decomposition pathways of the supercell structures of ε, β and γ modifications at different temperatures were studied by molecular dynamics simulations, using the ReaxFF force field, the NPT and NVT ensembles and the Berendsen methods.The results show that the initial pathway of different CL-20polymorphs is only the N-NO2dissociation to forming·NO2radical fragments, and the main thermal decomposition products are N2, H2O, CO, CO2, NO2, NO3, HNO2, HNO3, N2O5, N2O2and NO.The reaction rate constants of main products with the same modification increase with the increasing of temperature.
2014, 34(2): 195-201.
doi: 10.11883/1001-1455(2014)02-0195-07
Abstract:
The sandstone samples were heated at the rising temperature rate of 10℃/min from 25℃ to 100, 200, 400, 600, 800 and 1 000℃, respectively, by using a RX3-20-12box-type resistance furnace.They were being kept at the corresponding temperatures for 3h.Then the heated sandstone samples were naturally cooled to 25℃.All the sandstone samples were divided into seven groups according to the temperatures undergone by them.By using a thin red copper circular plate as the pulse shaper, the sandstone samples were impacted by the different-velocity projectiles driven by a 100-mmdiameter split Hopkinson pressure bar setup.And the stress-strain curves of the sandstone samples subjected to impact were obtained as well as their failure modes.Experimental results show that the stress-strain curves of the sandstone samples at constant temperature obviously take on four stages, but the platform stages disappear in the stress-strain curves of the sandstone samples undergoing 100-400℃ and they appear again when the temperatures undergone by the sandstone samples continue to rise.As the temperatures undergone by the sandstone samples rise, their peak strains and stresses increase; but when the temperatures undergone exceed 800℃, the peak stresses fall suddenly.The impact load and the heat temperature can affect the failure mode of sandstone, the break degree increases with the increasing of the impact load and the damage develops from the outer of sandstone to the core.
The sandstone samples were heated at the rising temperature rate of 10℃/min from 25℃ to 100, 200, 400, 600, 800 and 1 000℃, respectively, by using a RX3-20-12box-type resistance furnace.They were being kept at the corresponding temperatures for 3h.Then the heated sandstone samples were naturally cooled to 25℃.All the sandstone samples were divided into seven groups according to the temperatures undergone by them.By using a thin red copper circular plate as the pulse shaper, the sandstone samples were impacted by the different-velocity projectiles driven by a 100-mmdiameter split Hopkinson pressure bar setup.And the stress-strain curves of the sandstone samples subjected to impact were obtained as well as their failure modes.Experimental results show that the stress-strain curves of the sandstone samples at constant temperature obviously take on four stages, but the platform stages disappear in the stress-strain curves of the sandstone samples undergoing 100-400℃ and they appear again when the temperatures undergone by the sandstone samples continue to rise.As the temperatures undergone by the sandstone samples rise, their peak strains and stresses increase; but when the temperatures undergone exceed 800℃, the peak stresses fall suddenly.The impact load and the heat temperature can affect the failure mode of sandstone, the break degree increases with the increasing of the impact load and the damage develops from the outer of sandstone to the core.
2014, 34(2): 202-208.
doi: 10.11883/1001-1455(2014)02-0202-07
Abstract:
Simulated ammunitions were equivalent to aluminum-shelled explosives and a new energetic fragment was designed.The nonlinear dynamics software, LS-DYNA, was used to numerically simulate the complete processes of the energetic fragments penetrating the cover plates and detonating the shelled explosives.With the help of the up-and-down method, the impact velocities of the energetic fragments were calculated for detonating the shelled explosives with the cover plates of different thicknesses and compared with those of the solid fragments.The corresponding experiments were carried out to verify the typical data selected from the numerical simulations.The investigated results show that the explosives shelled by 8-16-mm thick aluminum covers can be effectively detonated by controlling the impact velocities of the energetic fragments and the detonation delay times of the energetic material in the fragments.
Simulated ammunitions were equivalent to aluminum-shelled explosives and a new energetic fragment was designed.The nonlinear dynamics software, LS-DYNA, was used to numerically simulate the complete processes of the energetic fragments penetrating the cover plates and detonating the shelled explosives.With the help of the up-and-down method, the impact velocities of the energetic fragments were calculated for detonating the shelled explosives with the cover plates of different thicknesses and compared with those of the solid fragments.The corresponding experiments were carried out to verify the typical data selected from the numerical simulations.The investigated results show that the explosives shelled by 8-16-mm thick aluminum covers can be effectively detonated by controlling the impact velocities of the energetic fragments and the detonation delay times of the energetic material in the fragments.
2014, 34(2): 209-215.
doi: 10.11883/1001-1455(2014)02-0209-07
Abstract:
To explore the transient response of a cylindrical cavity in an infinite elastic soil body to sudden anti -plane impact, the general analytical expressions were given for the displacement and stress of the soil, respectively, by using the Laplace transform.And the corresponding numerical solutions were presented.In the time domain, the dynamic responses of the infinite elastic soil to the impact load along the axial of the cavity were analyzed, and the computed results were compared with those from the numerical inversion proposed by Durbin and the static results.And there are some understandings of shear wave propagation as follows: the stress and displacement of the soil can increase instantaneously when the shear wave arrives here, then decrease gradually and tend to the static values; the shear wave spreads outward and attenuates along the radial directions, the attenuation rate is lower than that under static conditions.
To explore the transient response of a cylindrical cavity in an infinite elastic soil body to sudden anti -plane impact, the general analytical expressions were given for the displacement and stress of the soil, respectively, by using the Laplace transform.And the corresponding numerical solutions were presented.In the time domain, the dynamic responses of the infinite elastic soil to the impact load along the axial of the cavity were analyzed, and the computed results were compared with those from the numerical inversion proposed by Durbin and the static results.And there are some understandings of shear wave propagation as follows: the stress and displacement of the soil can increase instantaneously when the shear wave arrives here, then decrease gradually and tend to the static values; the shear wave spreads outward and attenuates along the radial directions, the attenuation rate is lower than that under static conditions.
2014, 34(2): 216-222.
doi: 10.11883/1001-1455(2014)02-0216-07
Abstract:
The highly-fluidized geopolymer concrete(HFGC)with the strength grade of C30was prepared by using slag and fly ash as raw material as well as NaOH and Na2CO3as alkali activator.Dynamic compression tests were carried out for the prepared HFGC specimens by using the 100-mm-diameter split Hopkinson pressure bar (SHPB)apparatus improved by the pulse-shaping technique.And in the dynamic compression tests, the dynamic stress equilibrium and the nearly constant strain rate loading were achieved by controlling the technique parameters.Based on the above tests, the deformation behaviors of the HFGC under the impact loadings were analyzed.The HFGC belongs to brittle and strain-rate sensitive materials.The typical stress-strain curve of the HFGC concludes compaction stage, elastic stage, softening and yielding stage at high strain rates.In the strain rate range from 10to 100s-1, the variation of the HFGC's peak strain with stain rate embodies obvious impact toughening, the peak strain increases firstly and then decreases with rising stain rate.And the overall change accords with the quadratic functionεc=-1.2×10-6
The highly-fluidized geopolymer concrete(HFGC)with the strength grade of C30was prepared by using slag and fly ash as raw material as well as NaOH and Na2CO3as alkali activator.Dynamic compression tests were carried out for the prepared HFGC specimens by using the 100-mm-diameter split Hopkinson pressure bar (SHPB)apparatus improved by the pulse-shaping technique.And in the dynamic compression tests, the dynamic stress equilibrium and the nearly constant strain rate loading were achieved by controlling the technique parameters.Based on the above tests, the deformation behaviors of the HFGC under the impact loadings were analyzed.The HFGC belongs to brittle and strain-rate sensitive materials.The typical stress-strain curve of the HFGC concludes compaction stage, elastic stage, softening and yielding stage at high strain rates.In the strain rate range from 10to 100s-1, the variation of the HFGC's peak strain with stain rate embodies obvious impact toughening, the peak strain increases firstly and then decreases with rising stain rate.And the overall change accords with the quadratic functionεc=-1.2×10-6
2014, 34(2): 223-228.
doi: 10.11883/1001-1455(2014)02-0223-06
Abstract:
To achieve the dynamic loadings on the large -sized specimens by the explosive shock waves equivalent to the stress wave obtained by a light -gas gun, based on the principle of superposition, the reverse detonation model was introduced to accomplish the shock wave loading on the compressible solid materials.The interferences were comprehensively considered for each free edge of the explosives and the material specimens by the rarefaction waves.By integrating the velocity-pressure curves of the explosion products and the compressible fluids, the calculation methods were theoretically proposed for the shock pressure and the shock wave loading platform width, respectively.And the theoretical analysis results were verified by combining the numerical simulation.They are consistent with each other.
To achieve the dynamic loadings on the large -sized specimens by the explosive shock waves equivalent to the stress wave obtained by a light -gas gun, based on the principle of superposition, the reverse detonation model was introduced to accomplish the shock wave loading on the compressible solid materials.The interferences were comprehensively considered for each free edge of the explosives and the material specimens by the rarefaction waves.By integrating the velocity-pressure curves of the explosion products and the compressible fluids, the calculation methods were theoretically proposed for the shock pressure and the shock wave loading platform width, respectively.And the theoretical analysis results were verified by combining the numerical simulation.They are consistent with each other.
2014, 34(2): 229-234.
doi: 10.11883/1001-1455(2014)02-0229-06
Abstract:
Based on ANSYS/LS -DYNA, the ALE method was used to describe the explosive and the air flow field, and the Lagrange method was used to describe the glasses.And the tensile stress failure of the glasses was considered as well as the shear -strain failure criterion.The corresponding calculation models and parameters were given for three kinds of architectural glass, respectively.Moreover, the numerical simulations were carried out to analyze the action processes of the explosion shock waves on the toughened PVB -laminated glass, the common PVB -laminated glass and the float glass, respectively.And the anti -explosion experiments were performed on these three glasses to compare with the numerical simulations.The comparisons show that the numerical results can reflect the punching failure phenomena of the glasses in the experiments.When the glasses occur to failure, their shock wave overpressures by numerical simulation are in agreement with the experimental results.Furthermore, the investigated results display that the toughened PVB -laminated glass has a higher explosion resistance than the common PVB -laminated glass and the PVB in the laminated glass can effectively prevent the glass from splashing.
Based on ANSYS/LS -DYNA, the ALE method was used to describe the explosive and the air flow field, and the Lagrange method was used to describe the glasses.And the tensile stress failure of the glasses was considered as well as the shear -strain failure criterion.The corresponding calculation models and parameters were given for three kinds of architectural glass, respectively.Moreover, the numerical simulations were carried out to analyze the action processes of the explosion shock waves on the toughened PVB -laminated glass, the common PVB -laminated glass and the float glass, respectively.And the anti -explosion experiments were performed on these three glasses to compare with the numerical simulations.The comparisons show that the numerical results can reflect the punching failure phenomena of the glasses in the experiments.When the glasses occur to failure, their shock wave overpressures by numerical simulation are in agreement with the experimental results.Furthermore, the investigated results display that the toughened PVB -laminated glass has a higher explosion resistance than the common PVB -laminated glass and the PVB in the laminated glass can effectively prevent the glass from splashing.
2014, 34(2): 235-240.
doi: 10.11883/1001-1455(2014)02-0235-06
Abstract:
A hemispherical liner was designed and the cushion with the same curvature as the liner was placed between the liner and the explosive.And the forming process of an explosively -formed penetrator from the liner made by reactive material was recorded by using a high -speed camera.Experimental results show that the liner made by reactive materials can be forged into an energetic penetrator under explosive loading and the velocity of the energetic penetrator can be up to about 2km/s.After perforating the armor steel target with the thickness of 20mm, the energetic penetrator reacts acutely and produces a great deal of gas.The penetrating process of the energetic penetrator is maintained by kinetic energy and chemical reaction.Ablation can obviously be observed during perforation.The diameter of perforation is about 0.5times as large as the diameter of charge and the penetrating depth is about 1.1times as large as the diameter of charge.
A hemispherical liner was designed and the cushion with the same curvature as the liner was placed between the liner and the explosive.And the forming process of an explosively -formed penetrator from the liner made by reactive material was recorded by using a high -speed camera.Experimental results show that the liner made by reactive materials can be forged into an energetic penetrator under explosive loading and the velocity of the energetic penetrator can be up to about 2km/s.After perforating the armor steel target with the thickness of 20mm, the energetic penetrator reacts acutely and produces a great deal of gas.The penetrating process of the energetic penetrator is maintained by kinetic energy and chemical reaction.Ablation can obviously be observed during perforation.The diameter of perforation is about 0.5times as large as the diameter of charge and the penetrating depth is about 1.1times as large as the diameter of charge.
Application of M1approach to numerical simulation of radiative transfer in strong explosion fireball
2014, 34(2): 241-246.
doi: 10.11883/1001-1455(2014)02-0241-06
Abstract:
According to the equations for the P1, Minerbo and M1approach models, the variations of their Eddington factors with the anisotropy factors were derived as well as the maximum eigenvalues of the moment equations of the radiative transfer against the anisotropy factors, respectively.And the M1approach model was used to numerically simulate the firball radiatve transfer from a 1 -kt TNT equivalent explosion.The fireball and shock wave fronts were given and compared with those by the different approach models.Numerical experiments show that the radiation wave velocity by the M1 approach is faster than that by the P1approach, but slower than that by the Minerbo approach.In the stage of the shock wave expansion, the radiation wave velocities by these three approaches are consistent with each other.
According to the equations for the P1, Minerbo and M1approach models, the variations of their Eddington factors with the anisotropy factors were derived as well as the maximum eigenvalues of the moment equations of the radiative transfer against the anisotropy factors, respectively.And the M1approach model was used to numerically simulate the firball radiatve transfer from a 1 -kt TNT equivalent explosion.The fireball and shock wave fronts were given and compared with those by the different approach models.Numerical experiments show that the radiation wave velocity by the M1 approach is faster than that by the P1approach, but slower than that by the Minerbo approach.In the stage of the shock wave expansion, the radiation wave velocities by these three approaches are consistent with each other.
2014, 34(2): 247-251.
doi: 10.11883/1001-1455(2014)02-0247-05
Abstract:
Aimed to a granular system composed of spherical particles, the particles were divided into a spring -spherical elements system based on the discrete element method.The calculation models were given for the elastic and contact forces between discrete elements.And the Mohr -Coulomb failure rule was used to estimate the fragmentation of the discrete elements.The above methods were applied to numerically simulate the impact fragmentation process of the granular system composed of brittle material in a cylinder.In the numerical simulations, the fragmentation states of each particle in the granular system at different times were followed.And the main influencing factors were analyzed on the simulated results.The investigations display that in the numerical simulation, it is necessary to consider the balance between computational accuracy and time.And under the same computational conditions, the calculated fragmentation degrees of granular systems will vary with the packing ways of the particles.
Aimed to a granular system composed of spherical particles, the particles were divided into a spring -spherical elements system based on the discrete element method.The calculation models were given for the elastic and contact forces between discrete elements.And the Mohr -Coulomb failure rule was used to estimate the fragmentation of the discrete elements.The above methods were applied to numerically simulate the impact fragmentation process of the granular system composed of brittle material in a cylinder.In the numerical simulations, the fragmentation states of each particle in the granular system at different times were followed.And the main influencing factors were analyzed on the simulated results.The investigations display that in the numerical simulation, it is necessary to consider the balance between computational accuracy and time.And under the same computational conditions, the calculated fragmentation degrees of granular systems will vary with the packing ways of the particles.
2014, 34(2): 252-256.
doi: 10.11883/1001-1455(2014)02-0252-05
Abstract:
A pulse forming network (PFN)discharge module and a spectroscopy system were employed to discuss the electrical explosion of copper wire.The plasma emission spectra were obtained in the wavelength range of 400-500nm by an Andor SR750spectrograph.Based on the thermodynamic equilibrium theory, the arc plasma excitation temperature was calculated by the relative line intensities.And the variation characteristic of the excitation temperature was discussed.The results show that the steady -state plasma excitation temperature by the exploding copper wire is approximately 5400K.The excitation temperature changes obviously in the prophase of the pulse discharge and it is relatively stable at the later stage of the pulse discharge.The excitation temperature difference during the whole pulse time is about 800K.
A pulse forming network (PFN)discharge module and a spectroscopy system were employed to discuss the electrical explosion of copper wire.The plasma emission spectra were obtained in the wavelength range of 400-500nm by an Andor SR750spectrograph.Based on the thermodynamic equilibrium theory, the arc plasma excitation temperature was calculated by the relative line intensities.And the variation characteristic of the excitation temperature was discussed.The results show that the steady -state plasma excitation temperature by the exploding copper wire is approximately 5400K.The excitation temperature changes obviously in the prophase of the pulse discharge and it is relatively stable at the later stage of the pulse discharge.The excitation temperature difference during the whole pulse time is about 800K.
