2009 Vol. 29, No. 2
Display Method:
2009, 29(2): 113-118.
doi: 10.11883/1001-1455(2009)02-0113-06
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Abstract:
A novel facility for tensile testing at the critical impact velocity was designed in a gas gun system. This facility consists of two assemblies, firstly, a gas gun system to propel the projectile and secondly, the tension mechanism to grip and strain the specimen bars. The critical impact velocity experiments in tension of oxygen-free high-conductivity copper were carried out using the novel facility. A numerical simulation was presented for uniaxial tensile testing at the critical impact velocity in complete thermal coupling. In case of necking, the plastic constraint factor, the void growth and coalescence were considered. The computed results with the Johnson-Cook or Zerilli-Armstrong constitutive relations, respectively, show that the Zerilli-Armstrong constitutive relation give a better prediction of the experimental critical impact velocity in tension for oxygen-free high-conductivity copper.
A novel facility for tensile testing at the critical impact velocity was designed in a gas gun system. This facility consists of two assemblies, firstly, a gas gun system to propel the projectile and secondly, the tension mechanism to grip and strain the specimen bars. The critical impact velocity experiments in tension of oxygen-free high-conductivity copper were carried out using the novel facility. A numerical simulation was presented for uniaxial tensile testing at the critical impact velocity in complete thermal coupling. In case of necking, the plastic constraint factor, the void growth and coalescence were considered. The computed results with the Johnson-Cook or Zerilli-Armstrong constitutive relations, respectively, show that the Zerilli-Armstrong constitutive relation give a better prediction of the experimental critical impact velocity in tension for oxygen-free high-conductivity copper.
2009, 29(2): 119-124.
doi: 10.11883/1001-1455(2009)02-0119-06
Abstract:
A large-size Hopkinson pressure bar equipment was used to explore the spall fracture properties of steel-fiber-reinforced concrete (SFRC) by analyzing the strain wave profiles in the absorption bar behind the specimen. The experimental results indicate that the spall strength of the SFRC is related to the steel-fiber volume fraction, the compressive strength of concretes and the load rate. And the proposed empirical formula shows the above relationship. Compared with the plain concretes, the SFRC has higher spall strength and more ability to prevent damage evolution and crack growth. The spall fracture processes of the SFRC recorded with a high-speed camera display that the flaking-off of scabs are due to the momentum effect of stress wave trapped in scabs and there lie few multiple fractures in scabs. These fracture phenomena of the SFRC differ distinctly from those of the plain concretes under the same loading conditions. It explains that steel fibers can improve the ability of concrete to prevent spall fracture. Investigated conclusion is helpful to the corresponding numerical simulation and engineering design.
A large-size Hopkinson pressure bar equipment was used to explore the spall fracture properties of steel-fiber-reinforced concrete (SFRC) by analyzing the strain wave profiles in the absorption bar behind the specimen. The experimental results indicate that the spall strength of the SFRC is related to the steel-fiber volume fraction, the compressive strength of concretes and the load rate. And the proposed empirical formula shows the above relationship. Compared with the plain concretes, the SFRC has higher spall strength and more ability to prevent damage evolution and crack growth. The spall fracture processes of the SFRC recorded with a high-speed camera display that the flaking-off of scabs are due to the momentum effect of stress wave trapped in scabs and there lie few multiple fractures in scabs. These fracture phenomena of the SFRC differ distinctly from those of the plain concretes under the same loading conditions. It explains that steel fibers can improve the ability of concrete to prevent spall fracture. Investigated conclusion is helpful to the corresponding numerical simulation and engineering design.
2009, 29(2): 125-130.
doi: 10.11883/1001-1455(2009)02-0125-06
Abstract:
Blast wave produced by an outer-sphere charge exploding in water of infinite depth was numerically simulated by solving the one-dimensional hydrodynamic equations for an inviscid and non-heat-conducting flow.In the simulation calculation, a Jones-Wilkins-Lee equation of state for TNT and a two-phase equation of state for water were adopted. The interface between the explosion products and water was determined by using the level set method.Firstly, grid-size effects on the convergence of the calculated results were explored. And the characters of pressure and impulse of underwater blast wave in the short range were investigated in detail. Finally, the approximate formulas for the peak pressure, specific impulse and attenuation constant were obtained by curve fitting.
Blast wave produced by an outer-sphere charge exploding in water of infinite depth was numerically simulated by solving the one-dimensional hydrodynamic equations for an inviscid and non-heat-conducting flow.In the simulation calculation, a Jones-Wilkins-Lee equation of state for TNT and a two-phase equation of state for water were adopted. The interface between the explosion products and water was determined by using the level set method.Firstly, grid-size effects on the convergence of the calculated results were explored. And the characters of pressure and impulse of underwater blast wave in the short range were investigated in detail. Finally, the approximate formulas for the peak pressure, specific impulse and attenuation constant were obtained by curve fitting.
2009, 29(2): 131-136.
doi: 10.11883/1001-1455(2009)02-0131-06
Abstract:
For investigating the delayed detonation phenomenon of the solid propellant initiated by low magnitude shock waves, the double card gap tests for the solid propellant mainly consisting of Al, HMX and AP were conducted. In the tests, the delayed detonation of the solid propellant was recorded with an X-ray camera. The numerical simulations of the double card gap tests were performed. An Ignition and Growth reaction rate equation was used to calculate the detonation initiation of the solid propellant subjected to multi-shock loading.The pressure histories in the solid propellant loaded by multi-shock waves were given. Both the experimental and calculated results show that delayed detonation phenomenon of the solid propellant initiated by low magnitude shock waves can happen. The repetitive loading conditions by shock waves and the sensitization levels of the solid propellant under shock wave loadings are the main factors for controlling the delayed detonation of the solid propellant.
For investigating the delayed detonation phenomenon of the solid propellant initiated by low magnitude shock waves, the double card gap tests for the solid propellant mainly consisting of Al, HMX and AP were conducted. In the tests, the delayed detonation of the solid propellant was recorded with an X-ray camera. The numerical simulations of the double card gap tests were performed. An Ignition and Growth reaction rate equation was used to calculate the detonation initiation of the solid propellant subjected to multi-shock loading.The pressure histories in the solid propellant loaded by multi-shock waves were given. Both the experimental and calculated results show that delayed detonation phenomenon of the solid propellant initiated by low magnitude shock waves can happen. The repetitive loading conditions by shock waves and the sensitization levels of the solid propellant under shock wave loadings are the main factors for controlling the delayed detonation of the solid propellant.
2009, 29(2): 137-142.
doi: 10.11883/1001-1455(2009)02-0137-06
Abstract:
The split Hopkinson pressure bar (SHPB) tests for concrete were numerically simulated by using the Holmquist-Johnson-Cook (HJC) constitutive model. The contact stiffness in the penalty function algorithm was reasonably determined. The stress-strain curves of the concrete specimens were reconstructed from the simulated results by applying the two-wave method used in the data processing of the SHPB tests. The effective ranges of the stress-strain curves obained in the SHPB tests and their mechanical regularity were analyzed. By comparing the stress-strain curve obtained from the SHPB test with the reconstructed curve from the numerical simulation, it can be found that the mechanical behaviors of the two curves are similar. It is verified that the HJC model is a reasonable constitutive model for describing the concrete materials. Numerical simulations were carried out for the SHPB tests of the concrete specimens with different tolerances in parallel. The simulated results show that the tolerances in parallel of specimens affect the SHPB tests much more remarkably than the stress(strain) nonuniformity in a certain strain-rate range.
The split Hopkinson pressure bar (SHPB) tests for concrete were numerically simulated by using the Holmquist-Johnson-Cook (HJC) constitutive model. The contact stiffness in the penalty function algorithm was reasonably determined. The stress-strain curves of the concrete specimens were reconstructed from the simulated results by applying the two-wave method used in the data processing of the SHPB tests. The effective ranges of the stress-strain curves obained in the SHPB tests and their mechanical regularity were analyzed. By comparing the stress-strain curve obtained from the SHPB test with the reconstructed curve from the numerical simulation, it can be found that the mechanical behaviors of the two curves are similar. It is verified that the HJC model is a reasonable constitutive model for describing the concrete materials. Numerical simulations were carried out for the SHPB tests of the concrete specimens with different tolerances in parallel. The simulated results show that the tolerances in parallel of specimens affect the SHPB tests much more remarkably than the stress(strain) nonuniformity in a certain strain-rate range.
2009, 29(2): 143-148.
doi: 10.11883/1001-1455(2009)02-0143-06
Abstract:
To investigate into the deformation of the Mach stem in a strong shock reflection, the flow field near the intersection point between slip line and wedge surface was theoretically analyzed, and a transition criterion for Mach stem deformation to disappear was derived, which was solved with the shock polar method. Processes of Mach stem deformation were described, and effects of ratio of specific heats and Mach number on conditions for Mach stem deformation to disappear, which were compared with those in presence of terminal double Mach reflections, were investigated. The results show that the disappearance of Mach stem deformation is a reflection phenomenon of shock waves in mediums with low ratios of specific heats. The disappearance of Mach stem protrusion leads to a new configuration of double Mach reflection with a straight Mach stem and no wall jet.
To investigate into the deformation of the Mach stem in a strong shock reflection, the flow field near the intersection point between slip line and wedge surface was theoretically analyzed, and a transition criterion for Mach stem deformation to disappear was derived, which was solved with the shock polar method. Processes of Mach stem deformation were described, and effects of ratio of specific heats and Mach number on conditions for Mach stem deformation to disappear, which were compared with those in presence of terminal double Mach reflections, were investigated. The results show that the disappearance of Mach stem deformation is a reflection phenomenon of shock waves in mediums with low ratios of specific heats. The disappearance of Mach stem protrusion leads to a new configuration of double Mach reflection with a straight Mach stem and no wall jet.
2009, 29(2): 149-154.
doi: 10.11883/1001-1455(2009)02-0149-06
Abstract:
Based on depth of penetration experiments, anti-penetration experiments were conducted in constrained AD95 ceramic targets and 10%-zirconia-toughened alumina ceramic targets subjected to shaped charge jet penetration.The depth of penetration-time curves for these two types of ceramic targets and their residual penetration depths in validating targets were obtained, and these data were compared with the corresponding experimental data for 45 steel targets.Results show that the protection coefficients of these two types of ceramic targets are both bigger than 1.0, that the anti-penetration abilities of the constrained ceramic targets are improved distinctly, and that the anti-penetration abilities of the toughened ceramic targets are larger than those of the AD95 ceramic targets.Based on the experimental results, the anti-penetration mechanism of the constrained ceramic targets to shaped charge jets was analyzed, and the following conclusion is presented: the disturbance of back-explosion generated from the constrained boundary to the jet stability is the main cause why the constrained ceramics have better anti-penetration ability than the unconstrained ceramics.
Based on depth of penetration experiments, anti-penetration experiments were conducted in constrained AD95 ceramic targets and 10%-zirconia-toughened alumina ceramic targets subjected to shaped charge jet penetration.The depth of penetration-time curves for these two types of ceramic targets and their residual penetration depths in validating targets were obtained, and these data were compared with the corresponding experimental data for 45 steel targets.Results show that the protection coefficients of these two types of ceramic targets are both bigger than 1.0, that the anti-penetration abilities of the constrained ceramic targets are improved distinctly, and that the anti-penetration abilities of the toughened ceramic targets are larger than those of the AD95 ceramic targets.Based on the experimental results, the anti-penetration mechanism of the constrained ceramic targets to shaped charge jets was analyzed, and the following conclusion is presented: the disturbance of back-explosion generated from the constrained boundary to the jet stability is the main cause why the constrained ceramics have better anti-penetration ability than the unconstrained ceramics.
2009, 29(2): 155-161.
doi: 10.11883/1001-1455(2009)02-0155-07
Abstract:
Numerical analyses for structure-soil interaction were carried out to investigate the attenuation effect of open, inundated water and concrete-filled trenches on high-speed train loading-induced Rayleigh wave propagation. The acceleration and effective stress at some key points of a six-storey surface structure were comparatively studied with commercial software LS-DYNA for the protection of open trenches, inundated water trenches, concrete-filled trenches and no protection. Numerical results reveal that open trenches even inundated with water can effectively reduce peak acceleration and effective stress. However, concrete-filled trenches are not effective in the attenuations of peak acceleration and effective stress. Therefore, an open trench is still a good choice as a temporary protection barrier, though it is susceptible to collapse without effective support.
Numerical analyses for structure-soil interaction were carried out to investigate the attenuation effect of open, inundated water and concrete-filled trenches on high-speed train loading-induced Rayleigh wave propagation. The acceleration and effective stress at some key points of a six-storey surface structure were comparatively studied with commercial software LS-DYNA for the protection of open trenches, inundated water trenches, concrete-filled trenches and no protection. Numerical results reveal that open trenches even inundated with water can effectively reduce peak acceleration and effective stress. However, concrete-filled trenches are not effective in the attenuations of peak acceleration and effective stress. Therefore, an open trench is still a good choice as a temporary protection barrier, though it is susceptible to collapse without effective support.
2009, 29(2): 162-166.
doi: 10.11883/1001-1455(2009)02-0162-05
Abstract:
The dynamic tensile fracture of cylindrical OFHC copper subjected to converging waves induced by sliding detonation was experimentally investigated.The inner surface (or free-surface) velocity profiles were measured by the displacement interferometer system for any reflector (DISAR).Analysis to velocity profiles gives some lights on the spalling characteristics of copper. Firstly, if the thickness of the spall scab and the high explosive (HE) thicknesshe are both divided by the wall thickness h of OFHC copper, it follows that the relative thickness /h of the spall scab increases with the relative HE thickness he/h. This accords with the research results of the steel cylindrical shell under the similar loading, however, the critical value of he/h for shell spalling is dependent on its material. Secondly, by comparing with other literatures, it can be seen elementarily that the spall strength of OFHC copper depends weakly on the geometric structure but mainly on the pressure and duration of impact loading. Lastly, the spall strength of OFHC copper is slightly lowered when its thickness increases, where material viscosity and Taylor triangular wave attenuation both contribute, also the dispersion of material.
The dynamic tensile fracture of cylindrical OFHC copper subjected to converging waves induced by sliding detonation was experimentally investigated.The inner surface (or free-surface) velocity profiles were measured by the displacement interferometer system for any reflector (DISAR).Analysis to velocity profiles gives some lights on the spalling characteristics of copper. Firstly, if the thickness of the spall scab and the high explosive (HE) thicknesshe are both divided by the wall thickness h of OFHC copper, it follows that the relative thickness /h of the spall scab increases with the relative HE thickness he/h. This accords with the research results of the steel cylindrical shell under the similar loading, however, the critical value of he/h for shell spalling is dependent on its material. Secondly, by comparing with other literatures, it can be seen elementarily that the spall strength of OFHC copper depends weakly on the geometric structure but mainly on the pressure and duration of impact loading. Lastly, the spall strength of OFHC copper is slightly lowered when its thickness increases, where material viscosity and Taylor triangular wave attenuation both contribute, also the dispersion of material.
2009, 29(2): 167-171.
doi: 10.11883/1001-1455(2009)02-0167-05
Abstract:
The three-point bending test was performed to explore the dynamic anti-bending properties of ceramic materials by the improved Hopkinson pressure bar system. The tested ceramic specimens have different static bending strengths. The dimensionless deflection and deflection rate were defined and the deflection-maximum tensile stress curves for these ceramic materials were obtained under different deflection rates. The dynamic bending strengths of these ceramic materials were determined from the obtained deflection-maximum tensile stress curves. The measured results show that the deflection rate has intense effect on dynamic bending strength of the ceramics. Analyses on the validity of the dynamic three-point bending test and the dynamic damage indicate that the critical dynamic damage factor is related to the deflection rate.
The three-point bending test was performed to explore the dynamic anti-bending properties of ceramic materials by the improved Hopkinson pressure bar system. The tested ceramic specimens have different static bending strengths. The dimensionless deflection and deflection rate were defined and the deflection-maximum tensile stress curves for these ceramic materials were obtained under different deflection rates. The dynamic bending strengths of these ceramic materials were determined from the obtained deflection-maximum tensile stress curves. The measured results show that the deflection rate has intense effect on dynamic bending strength of the ceramics. Analyses on the validity of the dynamic three-point bending test and the dynamic damage indicate that the critical dynamic damage factor is related to the deflection rate.
2009, 29(2): 172-176.
doi: 10.11883/1001-1455(2009)02-0172-05
Abstract:
Underwater explosion tests were conducted in a water tank withstanding the explosion of a 8-kg-TNT equivalent charge.The far-field pressure-time curves of TNT, RS211, HLZY-1 and HLZY-3 were measured with the PCB138 pressure gauges. The shock wave performance parameters and the respective similarity constants of various explosives were calculated. It is suggested that the underwater shock wave propagation of the aluminized explosives follows an exponential similarity rule, the shock wave performance of the aluminized explosives is better than that of TNT explosive, and the shock wave performance of HLZY-1 is best in the aluminized explosives researched in this paper.
Underwater explosion tests were conducted in a water tank withstanding the explosion of a 8-kg-TNT equivalent charge.The far-field pressure-time curves of TNT, RS211, HLZY-1 and HLZY-3 were measured with the PCB138 pressure gauges. The shock wave performance parameters and the respective similarity constants of various explosives were calculated. It is suggested that the underwater shock wave propagation of the aluminized explosives follows an exponential similarity rule, the shock wave performance of the aluminized explosives is better than that of TNT explosive, and the shock wave performance of HLZY-1 is best in the aluminized explosives researched in this paper.
2009, 29(2): 177-181.
doi: 10.11883/1001-1455(2009)02-0177-05
Abstract:
A numerical simulation of the toroidal shock wave motion in a cylindrical shock tube was carried out using the discontinuous finite element method, which was developed to solve the axisymmetric Euler equations based on two-dimensional conservation laws. The computed results show the complicated flow field, which is formed by shock propagating in the cylindrical shock tube, can be captured efficiently using the discontinuous finite element method. The numerical solutions with steep gradients near the focusing point indicate the discontinuous finite element method has high resolution and there can not lie numerical oscillation and artificial viscosity near the discontinuous point.
A numerical simulation of the toroidal shock wave motion in a cylindrical shock tube was carried out using the discontinuous finite element method, which was developed to solve the axisymmetric Euler equations based on two-dimensional conservation laws. The computed results show the complicated flow field, which is formed by shock propagating in the cylindrical shock tube, can be captured efficiently using the discontinuous finite element method. The numerical solutions with steep gradients near the focusing point indicate the discontinuous finite element method has high resolution and there can not lie numerical oscillation and artificial viscosity near the discontinuous point.
2009, 29(2): 182-188.
doi: 10.11883/1001-1455(2009)02-0182-07
Abstract:
Adopting the wavelet packet analysis technique, the energy distribution of the vibration, which was induced in the process of tunnel blasting excavation under the high in-situ stress conditions, was obtained. Analysis on the test data shows that the frequency ranges of the vibration induced by the transient unloading of the in-situ stress(VI) and the vibration induced by blast load(VB) are almost the same, but the proportion of the low frequency energy in VI is higher than that in VB. The effect of the transient unloading depends on the magnitude of the in-situ stress for the transient unloading and the size of the unloading area, both of which are determined by the distribution of the blast holes and explosive circuit.
Adopting the wavelet packet analysis technique, the energy distribution of the vibration, which was induced in the process of tunnel blasting excavation under the high in-situ stress conditions, was obtained. Analysis on the test data shows that the frequency ranges of the vibration induced by the transient unloading of the in-situ stress(VI) and the vibration induced by blast load(VB) are almost the same, but the proportion of the low frequency energy in VI is higher than that in VB. The effect of the transient unloading depends on the magnitude of the in-situ stress for the transient unloading and the size of the unloading area, both of which are determined by the distribution of the blast holes and explosive circuit.
2009, 29(2): 189-193.
doi: 10.11883/1001-1455(2009)02-0189-05
Abstract:
Taking cavity expansion in an elastic medium as the object of study, using the theory that movement fields on the boundary conditions of velocity and stress have the same potential, applying Laplace transformation and its convolution theorem, transformation between two boundary conditions was obtained, and transformation between velocity field and stress field of the spherical wave was got. Taking a double-exponential decay of dynamic stress and a sine exponential decay of velocity for examples, characteristics of the movement field in the spherical wave were analyzed. Results show that there does not lie a simply linear relationship between the stress and velocity in the spherical wave. Compared with the plane wave, the particle velocity in the spherical wave is smaller. Critical factors resulting in these differences are the wave propagation distance and wave velocity in media, the smaller the wave propagation distance is and the bigger wave velocity in media is, the more distinct these differences are.
Taking cavity expansion in an elastic medium as the object of study, using the theory that movement fields on the boundary conditions of velocity and stress have the same potential, applying Laplace transformation and its convolution theorem, transformation between two boundary conditions was obtained, and transformation between velocity field and stress field of the spherical wave was got. Taking a double-exponential decay of dynamic stress and a sine exponential decay of velocity for examples, characteristics of the movement field in the spherical wave were analyzed. Results show that there does not lie a simply linear relationship between the stress and velocity in the spherical wave. Compared with the plane wave, the particle velocity in the spherical wave is smaller. Critical factors resulting in these differences are the wave propagation distance and wave velocity in media, the smaller the wave propagation distance is and the bigger wave velocity in media is, the more distinct these differences are.
2009, 29(2): 194-198.
doi: 10.11883/1001-1455(2009)02-0194-05
Abstract:
Aimed at the disadvantage of the traditional wavelet transform maximum modulus (WTMM) denoising method not to identify all signal characteristics, an improved denoising method based on the WTMM technique was proposed, by using adaptive decomposition dimension instead of dyadic scales, to meet the signal denoising demands. The improved WTMM method and the traditional WTMM method were applied to analyze the original blasting vibration signals. The denoised signal by the improved WTMM method is coaxially more distinct from the detected signals and has better continuity, and the signal-to-noise ratio is improved from 17.25 to 20.16. It is suggested that the improved WTMM method has better denoising effect than the traditional WTMM method.
Aimed at the disadvantage of the traditional wavelet transform maximum modulus (WTMM) denoising method not to identify all signal characteristics, an improved denoising method based on the WTMM technique was proposed, by using adaptive decomposition dimension instead of dyadic scales, to meet the signal denoising demands. The improved WTMM method and the traditional WTMM method were applied to analyze the original blasting vibration signals. The denoised signal by the improved WTMM method is coaxially more distinct from the detected signals and has better continuity, and the signal-to-noise ratio is improved from 17.25 to 20.16. It is suggested that the improved WTMM method has better denoising effect than the traditional WTMM method.
2009, 29(2): 199-204.
doi: 10.11883/1001-1455(2009)02-0199-06
Abstract:
The complex problem on damage experienced by missile projects impacted by blast wave was simplified to explore the damage mechanism of the missile structures. Mechanical damage of missile projects was estimated with the dynamics knowledge. A numerical code was developed by taking charge mass of the warhead, the distance between the explosion point and the missile, the surrounding pressure at the explosion altitude, the geometry size of the missile, and the performance of the missile against shock loading into account. A series of numerical calculations were carried out by the newly-developed program code to investigate the damage of the missile by blast wave, which was produced by the warhead in cases of different times, different locations, and different charge masses. The computational results are basically in accord with the theory. This can explain that the adopted model and calculation method are reasonable and they can be used to evaluate the vulnerability of missile projects under blast overpressure.
The complex problem on damage experienced by missile projects impacted by blast wave was simplified to explore the damage mechanism of the missile structures. Mechanical damage of missile projects was estimated with the dynamics knowledge. A numerical code was developed by taking charge mass of the warhead, the distance between the explosion point and the missile, the surrounding pressure at the explosion altitude, the geometry size of the missile, and the performance of the missile against shock loading into account. A series of numerical calculations were carried out by the newly-developed program code to investigate the damage of the missile by blast wave, which was produced by the warhead in cases of different times, different locations, and different charge masses. The computational results are basically in accord with the theory. This can explain that the adopted model and calculation method are reasonable and they can be used to evaluate the vulnerability of missile projects under blast overpressure.
2009, 29(2): 205-208.
doi: 10.11883/1001-1455(2009)02-0205-04
Abstract:
The voltage and current of an exploding wire before its complete evaporation was obtained experimentally, and the variation of wire resistance and other parameters were calculated based on the experimental results. Bennett and Hobsons models were applied in simulating the resistance variation under the experimental parameters. The comparison between the experimental and simulated results shows that these two models are useful to guide the practice. These two models are both effective before the complete evaporation of the wire and under certain initial voltages of the capacitor. When the initial voltage of the capacitor is higher, the energy deposition velocity is faster, the time needed for the wire to melt and vaporize is shorter, and there lies a maximum resistance of the wire during its electrical explosion.
The voltage and current of an exploding wire before its complete evaporation was obtained experimentally, and the variation of wire resistance and other parameters were calculated based on the experimental results. Bennett and Hobsons models were applied in simulating the resistance variation under the experimental parameters. The comparison between the experimental and simulated results shows that these two models are useful to guide the practice. These two models are both effective before the complete evaporation of the wire and under certain initial voltages of the capacitor. When the initial voltage of the capacitor is higher, the energy deposition velocity is faster, the time needed for the wire to melt and vaporize is shorter, and there lies a maximum resistance of the wire during its electrical explosion.
2009, 29(2): 209-212.
doi: 10.11883/1001-1455(2009)02-0209-04
Abstract:
A combinational equation of state based on the experimental isentropic data for detonation products was deduced. Different equations of state for detonation products were used to simulate numerically detonation behaviors of explosives. Comparison between the experimental and numerical results shows that the arrival times, pressure peaks and wave forms computed by the Jones-Wilkins-Lee (JWL) equation of state and the combinational equation of state are in better agreement with the experimental results than those computed by the Becker-Kistiakowsky-Wilson (BKW) isentropic equation of state.
A combinational equation of state based on the experimental isentropic data for detonation products was deduced. Different equations of state for detonation products were used to simulate numerically detonation behaviors of explosives. Comparison between the experimental and numerical results shows that the arrival times, pressure peaks and wave forms computed by the Jones-Wilkins-Lee (JWL) equation of state and the combinational equation of state are in better agreement with the experimental results than those computed by the Becker-Kistiakowsky-Wilson (BKW) isentropic equation of state.
2009, 29(2): 213-216.
doi: 10.11883/1001-1455(2009)02-0213-04
Abstract:
A water tank was designed to explore bubble pulses of underwater explosion. In the designed water tank, small-scale underwater explosion tests were conducted for different TNT-equivalent PETN charges of 0.125, 1.000, 3.370, 8.000 g. After explosion of the PETN charge, bubble pulses were obtained by a high-speed camera system. Variation of the bubble diameter, expanding and contracting velocities, and expanding and contracting accelerations with time was achieved in the bubble pulse process under the given experimental conditions. The data of the bubble diameter and pulse period were analyzed. These data for bubble pulse obtained in this research accord approximately with a similarity rule.
A water tank was designed to explore bubble pulses of underwater explosion. In the designed water tank, small-scale underwater explosion tests were conducted for different TNT-equivalent PETN charges of 0.125, 1.000, 3.370, 8.000 g. After explosion of the PETN charge, bubble pulses were obtained by a high-speed camera system. Variation of the bubble diameter, expanding and contracting velocities, and expanding and contracting accelerations with time was achieved in the bubble pulse process under the given experimental conditions. The data of the bubble diameter and pulse period were analyzed. These data for bubble pulse obtained in this research accord approximately with a similarity rule.
2009, 29(2): 217-220.
doi: 10.11883/1001-1455(2009)02-0217-04
Abstract:
Shock-induced temperature rise of the porous liner before collapse was calculated based on the Grneisen equation of state revised by Herrmann, effect of porosity on the shaped charge break-up time was analyzed theoretically. The stability of jets produced by shaped charges with two different porous liners was studied with flash X-ray and penetration tests. It is shown that the jet stability increases with the porosity within a certain range of porosity.
Shock-induced temperature rise of the porous liner before collapse was calculated based on the Grneisen equation of state revised by Herrmann, effect of porosity on the shaped charge break-up time was analyzed theoretically. The stability of jets produced by shaped charges with two different porous liners was studied with flash X-ray and penetration tests. It is shown that the jet stability increases with the porosity within a certain range of porosity.
2009, 29(2): 221-224.
doi: 10.11883/1001-1455(2009)02-0221-04
Abstract:
A bomb-borne solid-state recorder was proposed to record the explosion-induced high-shock signals.In this solid-state recorder, the FPGA device XC2S30 is used as the core controlling chip.With the joint function of the A/D controller, the high-speed state machine, the phase-delayed clock and the flash memory controller working in the recorder, it can transform the high shock signals into digital ones and store them into the main memory which is made up of flash memory. With the multi-layer cushions and double-walled steel structures, the high-shock signals for the whole dispersal and gunfire tests were successfully recorded by applying the proposed solid-state recorder.
A bomb-borne solid-state recorder was proposed to record the explosion-induced high-shock signals.In this solid-state recorder, the FPGA device XC2S30 is used as the core controlling chip.With the joint function of the A/D controller, the high-speed state machine, the phase-delayed clock and the flash memory controller working in the recorder, it can transform the high shock signals into digital ones and store them into the main memory which is made up of flash memory. With the multi-layer cushions and double-walled steel structures, the high-shock signals for the whole dispersal and gunfire tests were successfully recorded by applying the proposed solid-state recorder.
