2006 Vol. 26, No. 3
Display Method:
2006, 26(3): 193-198.
doi: 10.11883/1001-1455(2006)03-0193-06
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Abstract:
High-velocity deformation process of material is usually accompanied with interior damage evolution in different forms. Experimental observations for different materials show that damage evolution is dependent on strain, strain rate and temperature, and a certain equivalency exists between the strain rate effect and the temperature effect. Thus, based on the thermo-activation mechanism, a strain and strain-rate dependent damage evolution law and the corresponding rate-dependent constitutive relation taking account of damage evolution are proposed. As an example, the ZWT nonlinear viscoelastic constitutive relation taking account of damage-weakening effect is further studied, particularly the constitutive response and the response due to damage evolution can be distinguished.
High-velocity deformation process of material is usually accompanied with interior damage evolution in different forms. Experimental observations for different materials show that damage evolution is dependent on strain, strain rate and temperature, and a certain equivalency exists between the strain rate effect and the temperature effect. Thus, based on the thermo-activation mechanism, a strain and strain-rate dependent damage evolution law and the corresponding rate-dependent constitutive relation taking account of damage evolution are proposed. As an example, the ZWT nonlinear viscoelastic constitutive relation taking account of damage-weakening effect is further studied, particularly the constitutive response and the response due to damage evolution can be distinguished.
Three modes of penetration mechanics of A3 steel cylindrical projectiles impact onto 45 steel plates
2006, 26(3): 199-207.
doi: 10.11883/1001-1455(2006)03-0199-09
Abstract:
The ballistic trajectory effect of the fragment simulation projectile was experimentally researched by A3 steel cylindrical projectiles (diameter of projectile 25 mm) impacting 45 steel plates. The intensity of A3 steel is less than that of 45 steel. In the velocity ranges of 200～800 m/s, Taylor impact, petal-cap failure of sunflower alike and plugging perforation are observed respectively in the plates with increasing velocity. Complicated material failures of projectile and target conflict with the different penetration mechanisms.
The ballistic trajectory effect of the fragment simulation projectile was experimentally researched by A3 steel cylindrical projectiles (diameter of projectile 25 mm) impacting 45 steel plates. The intensity of A3 steel is less than that of 45 steel. In the velocity ranges of 200～800 m/s, Taylor impact, petal-cap failure of sunflower alike and plugging perforation are observed respectively in the plates with increasing velocity. Complicated material failures of projectile and target conflict with the different penetration mechanisms.
2006, 26(3): 208-213.
doi: 10.11883/1001-1455(2006)03-0208-06
Abstract:
Experimental and numerical investigations were performed on the CH4/Air mixture premixed flame propagation in a horizontal rectangle tube with a wedge obstacle mounted at the bottom. The multiple-lens, Cranz Schardin high speed video system and pressure transducer etc experimental equipment were adopted to visualize the interaction between the wedge block and flame and to measure the flow parameters. Sequences of high-speed images with high definition showing the process of a flame losing its stability under the action of the wedge obstacle and pressure history on the backside of the obstacle were gained. Based on RANS method and EBU-Arrhenius combustion model, a numerical simulation was carried out to simulate the above complex physical phenomenon. Both experimental and numerical results are in good agreement, which show the inherent mechanism of flame acceleration and its front distortion, as well as the nature of a transition from laminar combustion to turbulence during its propagation.
Experimental and numerical investigations were performed on the CH4/Air mixture premixed flame propagation in a horizontal rectangle tube with a wedge obstacle mounted at the bottom. The multiple-lens, Cranz Schardin high speed video system and pressure transducer etc experimental equipment were adopted to visualize the interaction between the wedge block and flame and to measure the flow parameters. Sequences of high-speed images with high definition showing the process of a flame losing its stability under the action of the wedge obstacle and pressure history on the backside of the obstacle were gained. Based on RANS method and EBU-Arrhenius combustion model, a numerical simulation was carried out to simulate the above complex physical phenomenon. Both experimental and numerical results are in good agreement, which show the inherent mechanism of flame acceleration and its front distortion, as well as the nature of a transition from laminar combustion to turbulence during its propagation.
2006, 26(3): 214-221.
doi: 10.11883/1001-1455(2006)03-0214-08
Abstract:
The numerical simulation was carried out for the dynamic response of crack subjected to the normal, shear and oblique impact loads. The dynamic stress field and the strain field were obtained. According to its definition, the corresponding dynamic stress intensity factor (DSIF) was calculated. The situation of initiation of crack impacted by oblique loads was analyzed, and the optimization fracture by stress pulses was discussed.
The numerical simulation was carried out for the dynamic response of crack subjected to the normal, shear and oblique impact loads. The dynamic stress field and the strain field were obtained. According to its definition, the corresponding dynamic stress intensity factor (DSIF) was calculated. The situation of initiation of crack impacted by oblique loads was analyzed, and the optimization fracture by stress pulses was discussed.
2006, 26(3): 222-227.
doi: 10.11883/1001-1455(2006)03-0222-06
Abstract:
Based on the characters of short duration and abrupt change of blasting seismic signals, and the monitoring data from a blasting engineering, energy distribution of blasting seismic signals are analyzed by using the time-frequency localization of wavelet. The law of energy change of blast seismic signals during the spread is studied, the energy distribution of blasting seismic signals in different frequency bands is obtained by means of the wavelet packet analysis, which has high resolvability and localization. Relations between characteristic frequency at different frequency bands of blasting seismic signals and natural frequency of controlled structures confirm the effect of blasting seism on the structures. An engineering example illustrates that the proposed method is more effective than a single intensity factor as the safety judging standard for blasting seism.
Based on the characters of short duration and abrupt change of blasting seismic signals, and the monitoring data from a blasting engineering, energy distribution of blasting seismic signals are analyzed by using the time-frequency localization of wavelet. The law of energy change of blast seismic signals during the spread is studied, the energy distribution of blasting seismic signals in different frequency bands is obtained by means of the wavelet packet analysis, which has high resolvability and localization. Relations between characteristic frequency at different frequency bands of blasting seismic signals and natural frequency of controlled structures confirm the effect of blasting seism on the structures. An engineering example illustrates that the proposed method is more effective than a single intensity factor as the safety judging standard for blasting seism.
2006, 26(3): 228-233.
doi: 10.11883/1001-1455(2006)03-0228-06
Abstract:
To investigate the damage evolution of a reinforced aircraft skin impacted by a projectile with diameter 12.7 mm, LY-12 plate with thickness 3 mm and reinforced aircraft skin are shoot by the projectile. An effective testing system of simulating battle damage is experimentally developed, which consists of high pressed airgun, an assembled projectile body and bullet-shoe design, an instantaneous velocity measurement system with laser and lens, set-up frame for the specimens, and the projectile trap box. First, LY-12 CZ plates with thickness 3 mm are fixed around, and shoot by the projectile under the velocities from 60 m/s to 300 m/s. The results show that effective diameter of the deformation region by projectile impact decreases with increasing the velocity of the bullet, it follows a power law. The dynamic strain on the pate linearly decreases with increasing projectile velocity. The residual velocity of the bullet linearly rises with the velocities. Then, reinforced aircraft skins are tested by the same process as LY-12 CZ plates, the numerical simulations are performed. Comparison of the test results and numerical simulation show that the developed simulation technique is effective to simulate battle damage of the aircraft.
To investigate the damage evolution of a reinforced aircraft skin impacted by a projectile with diameter 12.7 mm, LY-12 plate with thickness 3 mm and reinforced aircraft skin are shoot by the projectile. An effective testing system of simulating battle damage is experimentally developed, which consists of high pressed airgun, an assembled projectile body and bullet-shoe design, an instantaneous velocity measurement system with laser and lens, set-up frame for the specimens, and the projectile trap box. First, LY-12 CZ plates with thickness 3 mm are fixed around, and shoot by the projectile under the velocities from 60 m/s to 300 m/s. The results show that effective diameter of the deformation region by projectile impact decreases with increasing the velocity of the bullet, it follows a power law. The dynamic strain on the pate linearly decreases with increasing projectile velocity. The residual velocity of the bullet linearly rises with the velocities. Then, reinforced aircraft skins are tested by the same process as LY-12 CZ plates, the numerical simulations are performed. Comparison of the test results and numerical simulation show that the developed simulation technique is effective to simulate battle damage of the aircraft.
2006, 26(3): 234-239.
doi: 10.11883/1001-1455(2006)03-0234-06
Abstract:
The explosion resistance performance of reinforced concrete (RC) slabs reinforced with glass fiber reinforced plastic (GFRP) ribbon and the common RC slab were experimentally studied to explore the strengthening effect of GFRP on RC structures under explosion load. The experimental results show that GFRP can prevent the development of concrete flaw and enhance the explosion resistance performance of RC slab. The researched result can provide a reference for reinforcement mechanism study of GFRP and explosion resistance design of RC slabs reinforced with GFRP.
The explosion resistance performance of reinforced concrete (RC) slabs reinforced with glass fiber reinforced plastic (GFRP) ribbon and the common RC slab were experimentally studied to explore the strengthening effect of GFRP on RC structures under explosion load. The experimental results show that GFRP can prevent the development of concrete flaw and enhance the explosion resistance performance of RC slab. The researched result can provide a reference for reinforcement mechanism study of GFRP and explosion resistance design of RC slabs reinforced with GFRP.
2006, 26(3): 240-244.
doi: 10.11883/1001-1455(2006)03-0240-05
Abstract:
The energy distribution for ground shock of explosion with different buried depths in soil is studied with numerical simulation method, and the coupling coefficient data is gained from test. The minimal scaled buried depth for close explosion in free-field is 2.0 m/kg1/3 gotten in the paper, there is much difference to the data 0.56 m/kg1/3 in Fundamentals of Protective Design for Conventional Weapons (TM5-855-1), and the reasons for difference are discussed. The coupling coefficient with impulse forms gotten in the paper is quite different to that with stress form in TM5-855-1, the range and object for using should be careful.
The energy distribution for ground shock of explosion with different buried depths in soil is studied with numerical simulation method, and the coupling coefficient data is gained from test. The minimal scaled buried depth for close explosion in free-field is 2.0 m/kg1/3 gotten in the paper, there is much difference to the data 0.56 m/kg1/3 in Fundamentals of Protective Design for Conventional Weapons (TM5-855-1), and the reasons for difference are discussed. The coupling coefficient with impulse forms gotten in the paper is quite different to that with stress form in TM5-855-1, the range and object for using should be careful.
2006, 26(3): 245-249.
doi: 10.11883/1001-1455(2006)03-0245-05
Abstract:
A magneto-rheological (MR) recoil damper for a 25 mm air defence gun test application is studied. Based on Herschel-Bulkley shear model, a one-dimensional axisymmetric laminar flow model of the MR recoil damper is proposed, and the relation curves of damping force and piston velocity of the MR damper are obtained according to the proposed model. Using the force-velocity characteristics of the MR damper, the recoil dynamic equation of the 25 mm gun is solved, and the recoil velocity and recoil displacement of the gun are obtained. The simulation results indicate that the value of the MR fluid behavior index has a very big influence on performance of the gun magneto-rheological (MR) recoil damper.
A magneto-rheological (MR) recoil damper for a 25 mm air defence gun test application is studied. Based on Herschel-Bulkley shear model, a one-dimensional axisymmetric laminar flow model of the MR recoil damper is proposed, and the relation curves of damping force and piston velocity of the MR damper are obtained according to the proposed model. Using the force-velocity characteristics of the MR damper, the recoil dynamic equation of the 25 mm gun is solved, and the recoil velocity and recoil displacement of the gun are obtained. The simulation results indicate that the value of the MR fluid behavior index has a very big influence on performance of the gun magneto-rheological (MR) recoil damper.
2006, 26(3): 250-255.
doi: 10.11883/1001-1455(2006)03-0250-06
Abstract:
Based on dynamics of explosion and fracture mechanics, the mechanism of crack initiation and its expansion of directional fracture controlled blasting by shaped charge with wedge-type liners in rock were studied，the blasting parameters were designed and tested in field. The results show that the energy from blasting be directionally concentrated by the joint-cutting produced by cumulative jet. The directional expansion of crack is satisfactory, field test suggest that this blasting is a good means in excavating tunnels or cutting rock. It points out the aspects of this method need to be studied further. All these will give beneficial references to related theoretical study and field application.
Based on dynamics of explosion and fracture mechanics, the mechanism of crack initiation and its expansion of directional fracture controlled blasting by shaped charge with wedge-type liners in rock were studied，the blasting parameters were designed and tested in field. The results show that the energy from blasting be directionally concentrated by the joint-cutting produced by cumulative jet. The directional expansion of crack is satisfactory, field test suggest that this blasting is a good means in excavating tunnels or cutting rock. It points out the aspects of this method need to be studied further. All these will give beneficial references to related theoretical study and field application.
2006, 26(3): 256-261.
doi: 10.11883/1001-1455(2006)03-0256-06
Abstract:
The dynamic displacement ductility and ultimate load-carrying capability of three partially-prestressed concrete (PPC) beams which were unbonded, were experimentally obtained by applying impact load to their middle with dropping hammers, and the typical measurement wave curves were given. Influences of a dropping hammers gravitational potential energy on the dynamic properties of the PPC beam were analyzed. Based on the analog simulation theory, the impact-load-carrying capability of the real unbonded PPC beam with span 12 m was gained. Results show that the unbonded PPC beams anti-impact properties are good, the fragile destruction will not happen, and the unbonded PPC beams can be used in wide-span underground structures.
The dynamic displacement ductility and ultimate load-carrying capability of three partially-prestressed concrete (PPC) beams which were unbonded, were experimentally obtained by applying impact load to their middle with dropping hammers, and the typical measurement wave curves were given. Influences of a dropping hammers gravitational potential energy on the dynamic properties of the PPC beam were analyzed. Based on the analog simulation theory, the impact-load-carrying capability of the real unbonded PPC beam with span 12 m was gained. Results show that the unbonded PPC beams anti-impact properties are good, the fragile destruction will not happen, and the unbonded PPC beams can be used in wide-span underground structures.
2006, 26(3): 262-268.
doi: 10.11883/1001-1455(2006)03-0262-07
Abstract:
The response of ship structure and the effectiveness of various armor structure under ballistic impact of small caliber artillery were studied experimentally. Ballistic impact experiment was carried out to simulate the impact of typical warhead of small caliber artillery. Projectile and 6 kinds of targets were designed according to the similarity theory of ballistic impact. The results show that the structure of ship cannot resist the attack from small caliber artillery, and special armor needs to be equipped. The combination armor of ceramic, steel, fiber reinforced composite can save 60% approximately in weight, compared with steel armor. The use of ceramic can change the failure mode and extent of steel back plate, and greatly improve its energy absorpation. In addition, ceramic can erode, mushroom and crash the projectile, those can greatly degrade its penetration performance.
The response of ship structure and the effectiveness of various armor structure under ballistic impact of small caliber artillery were studied experimentally. Ballistic impact experiment was carried out to simulate the impact of typical warhead of small caliber artillery. Projectile and 6 kinds of targets were designed according to the similarity theory of ballistic impact. The results show that the structure of ship cannot resist the attack from small caliber artillery, and special armor needs to be equipped. The combination armor of ceramic, steel, fiber reinforced composite can save 60% approximately in weight, compared with steel armor. The use of ceramic can change the failure mode and extent of steel back plate, and greatly improve its energy absorpation. In addition, ceramic can erode, mushroom and crash the projectile, those can greatly degrade its penetration performance.
2006, 26(3): 269-272.
doi: 10.11883/1001-1455(2006)03-0269-04
Abstract:
An embedded electromagnetic particle-velocity gauge was used to measure the shock initiation behavior in JOB-9003 explosive under different shock pressures. The particle velocity history profiles can fairly decribe the change processes from the shock waves to the detonation waves in the explosive. The output signal from a shock tracker shows that at the shock pressures of 4.9 GPa and 58 GPa, the critical times and distances for the onset of detonation of JOB-9003 explosive are respectively 6.06 mm and 1.13 s , 5.66 mm and 1.01 s.
An embedded electromagnetic particle-velocity gauge was used to measure the shock initiation behavior in JOB-9003 explosive under different shock pressures. The particle velocity history profiles can fairly decribe the change processes from the shock waves to the detonation waves in the explosive. The output signal from a shock tracker shows that at the shock pressures of 4.9 GPa and 58 GPa, the critical times and distances for the onset of detonation of JOB-9003 explosive are respectively 6.06 mm and 1.13 s , 5.66 mm and 1.01 s.
2006, 26(3): 273-278.
doi: 10.11883/1001-1455(2006)03-0273-06
Abstract:
The discrete principle of the material point method (MPM) was briefly introduced, and a three-dimensional MPM code (MPM3D) was developed with the Johnson-Cook material model and Mie-Gruneisen equation of state to analyze the hypervelocity impact problems. The MPM avoids difficulty resulted from mesh distortion as in the Lagrangian method, and overtakes interface tracking and nonlinear convection term as in Eulerian scheme. The Taylor impact and orbital debris shielding problems are simulated by the MPM3D, and the calculated results are in agreement with the experimental results. The MPM is more efficient than the FEM in the analysis of hypervelocity impact problems.
The discrete principle of the material point method (MPM) was briefly introduced, and a three-dimensional MPM code (MPM3D) was developed with the Johnson-Cook material model and Mie-Gruneisen equation of state to analyze the hypervelocity impact problems. The MPM avoids difficulty resulted from mesh distortion as in the Lagrangian method, and overtakes interface tracking and nonlinear convection term as in Eulerian scheme. The Taylor impact and orbital debris shielding problems are simulated by the MPM3D, and the calculated results are in agreement with the experimental results. The MPM is more efficient than the FEM in the analysis of hypervelocity impact problems.
2006, 26(3): 279-283.
doi: 10.11883/1001-1455(2006)03-0279-05
Abstract:
In blasting experiments, durations of subordinate basting seismic waves and intensity of influence among them are changed by adjusting the number of subordinate blasting, explosive weigh of subordinate blasting, total quantum of explosive, interval, hole-net parameters and wave resistance of rock, etc. Relation of blasting seismic intensity and related blasting parameters is researched to illustrate propagation law and damage performance of the blasting seismic wave, and influence extent of related blasting factors on blasting seismic intensity. The rule to determine the basting parameters is obtained to provide a theoretical foundation for the optimal design of the blasting parameters in productive practices.
In blasting experiments, durations of subordinate basting seismic waves and intensity of influence among them are changed by adjusting the number of subordinate blasting, explosive weigh of subordinate blasting, total quantum of explosive, interval, hole-net parameters and wave resistance of rock, etc. Relation of blasting seismic intensity and related blasting parameters is researched to illustrate propagation law and damage performance of the blasting seismic wave, and influence extent of related blasting factors on blasting seismic intensity. The rule to determine the basting parameters is obtained to provide a theoretical foundation for the optimal design of the blasting parameters in productive practices.
2006, 26(3): 284-288.
doi: 10.11883/1001-1455(2006)03-0284-04
Abstract:
Shock wave velocity in Teflon sample, average velocity and flatness of Mylar flyer plate driven by electronic gun were measured by fiber-optic pins. Experimental results show that quartz optical fiber pin diagnostic technology provides a direct, electronic noise immune，accurate shock diagnostic for nonmetallic material shock experiments.
Shock wave velocity in Teflon sample, average velocity and flatness of Mylar flyer plate driven by electronic gun were measured by fiber-optic pins. Experimental results show that quartz optical fiber pin diagnostic technology provides a direct, electronic noise immune，accurate shock diagnostic for nonmetallic material shock experiments.
