2005 Vol. 25, No. 1
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2005, 25(1): 1-4.
doi: 10.11883/1001-1455(2005)01-0001-04
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Abstract:
Starting from the momentum equation, a projection angle equation of the planar flyer plate under detonation driving is derived in the moving reference frame by regarding the material as incompressible fluid and considering the force between the neighbouring segments. The equivalence between the solution of the equation and the geometry relation of the vector triangle is also discussed.
Starting from the momentum equation, a projection angle equation of the planar flyer plate under detonation driving is derived in the moving reference frame by regarding the material as incompressible fluid and considering the force between the neighbouring segments. The equivalence between the solution of the equation and the geometry relation of the vector triangle is also discussed.
2005, 25(1): 5-10.
doi: 10.11883/1001-1455(2005)01-0005-06
Abstract:
The vented external flow field was visualized using the experimental and numerical methods. The YA-16 high speed shadowgraph system was adopted in test to obtain the consequential clear shadowgraphs of the external flow field. And the explosion venting was simulated by the colocated grid SIMPLE scheme, based on the K- turbulence model and eddy dissipation combustion model. Based on the numerical results, the computational shadowgraphs were obtained through computational flow imagines (CFI). Comparisons of the computational shadowgraphs to the experimental shadowgraphs showed good agreement in trend. Both the experimental and the computational shadowgraphs visually demonstrated the development of the turbulent flame and the formation and development of the secondary explosion during venting.
The vented external flow field was visualized using the experimental and numerical methods. The YA-16 high speed shadowgraph system was adopted in test to obtain the consequential clear shadowgraphs of the external flow field. And the explosion venting was simulated by the colocated grid SIMPLE scheme, based on the K- turbulence model and eddy dissipation combustion model. Based on the numerical results, the computational shadowgraphs were obtained through computational flow imagines (CFI). Comparisons of the computational shadowgraphs to the experimental shadowgraphs showed good agreement in trend. Both the experimental and the computational shadowgraphs visually demonstrated the development of the turbulent flame and the formation and development of the secondary explosion during venting.
2005, 25(1): 11-16.
doi: 10.11883/1001-1455(2005)01-0011-06
Abstract:
Based on the K- turbulence model and the eddy dissipation combustion model, the explosion venting to the air in a cylindrical vessel filled with the stoichiometric methane-air mixture was simulated using the colocated grid SIMPLE scheme. The dominant mechanisms of the occurrence of the secondary explosion during the venting processes were elucidated according to the numerical and relevant experimental results. After venting, there existed the low pressure area of rarefaction wave and the high pressure area of suspended shock inside the external combustible cloud forming from the discharged combustible gas. Under some suitable venting conditions, the violent combustion in the high pressure area was induced by the flame jet, which gave rise to the pressure increasing rapidly, and even the secondary explosion.
Based on the K- turbulence model and the eddy dissipation combustion model, the explosion venting to the air in a cylindrical vessel filled with the stoichiometric methane-air mixture was simulated using the colocated grid SIMPLE scheme. The dominant mechanisms of the occurrence of the secondary explosion during the venting processes were elucidated according to the numerical and relevant experimental results. After venting, there existed the low pressure area of rarefaction wave and the high pressure area of suspended shock inside the external combustible cloud forming from the discharged combustible gas. Under some suitable venting conditions, the violent combustion in the high pressure area was induced by the flame jet, which gave rise to the pressure increasing rapidly, and even the secondary explosion.
2005, 25(1): 17-25.
doi: 10.11883/1001-1455（2005）01-0017-09
Abstract:
Two approaches are usually used in the studies of dynamic constitutive relation of materials. One is to determine the constitutive relation from the wave propagating signals (the so-called second class of inverse problems). The another is to de-couple the stress wave effects of structures and the strain-rate effects of materials. In both approaches, stress wave propagation plays a key role. In the present paper, some important aspects associated with this problem are discussed, particularly in relation to the SHPB technique. Both the assumption of uniform distribution of stress and strain along the specimen and the assumption of uniaxial stress are analyzed in detail.
Two approaches are usually used in the studies of dynamic constitutive relation of materials. One is to determine the constitutive relation from the wave propagating signals (the so-called second class of inverse problems). The another is to de-couple the stress wave effects of structures and the strain-rate effects of materials. In both approaches, stress wave propagation plays a key role. In the present paper, some important aspects associated with this problem are discussed, particularly in relation to the SHPB technique. Both the assumption of uniform distribution of stress and strain along the specimen and the assumption of uniaxial stress are analyzed in detail.
2005, 25(1): 26-30.
doi: 10.11883/1001-1455(2005)01-0026-05
Abstract:
This article reports Ignition and Growth equations of aluminized explosives containing oxidizer (RDX/AP/Al/HTPB=20/43/25/12). VLW EOS (equations of state) is applied to calculate the parameters of JWL EOS for this explosives. The free-surface velocities of the metal plate and the interface particle velocities between the explosive and sodium chloride window were recorded by the VISAR velocity interferometer. We have performed 3D numerical simulation for the particle velocities test to evaluate the parameters of the reactive rate EOS. The results show that the VLW EOS method and the explosion/widow interface velocity can be used to determine the JWL EOS and the reactive rate EOS. The results of metal plate acceleration test agree well with calculations.
This article reports Ignition and Growth equations of aluminized explosives containing oxidizer (RDX/AP/Al/HTPB=20/43/25/12). VLW EOS (equations of state) is applied to calculate the parameters of JWL EOS for this explosives. The free-surface velocities of the metal plate and the interface particle velocities between the explosive and sodium chloride window were recorded by the VISAR velocity interferometer. We have performed 3D numerical simulation for the particle velocities test to evaluate the parameters of the reactive rate EOS. The results show that the VLW EOS method and the explosion/widow interface velocity can be used to determine the JWL EOS and the reactive rate EOS. The results of metal plate acceleration test agree well with calculations.
2005, 25(1): 31-34.
doi: 10.11883/1001-1455(2005)01-0031-04
Abstract:
A double sensitivity VISAR system is used to measure the flyer velocity of electrically exploding foil initiator. The flyer surface is treated by plating a metal film, which eliminates the interference caused by bridge foil exploding, and enhances the reflectivity of the flyer surface. For a EFIs with a 0.36 mm wide and 8.4 m thick bridge foil, and a 1.2 mm diameter and 0.12 mm thickness flyer, under 4.5 kV charge, the peak flyer velocity is 4.1 km/s, the accelerating duration is about 150 ns, and the displacement of the flyer is about 0.3 mm till reaching the peak velocity.
A double sensitivity VISAR system is used to measure the flyer velocity of electrically exploding foil initiator. The flyer surface is treated by plating a metal film, which eliminates the interference caused by bridge foil exploding, and enhances the reflectivity of the flyer surface. For a EFIs with a 0.36 mm wide and 8.4 m thick bridge foil, and a 1.2 mm diameter and 0.12 mm thickness flyer, under 4.5 kV charge, the peak flyer velocity is 4.1 km/s, the accelerating duration is about 150 ns, and the displacement of the flyer is about 0.3 mm till reaching the peak velocity.
2005, 25(1): 35-40.
doi: 10.11883/1001-1455(2005)01-0035-06
Abstract:
The anomalous response of elastic-plastic circular plate subjected to various rectangle and triangle impulse loadings is studied. The influences of various loading modes and loading areas on the counter-intuitive behavior of the plate are numerically analyzed in detail. The characteristics of the counter-intuitive behavior under different loadings are obtained. The relation between the number of the displacement peaks in the time-displacement curve and the loading range corresponding to the anomalous response is discovered. The results show that the minimum number of the successive counter-intuitive behaviors can be evaluated from the time-displacement curve corresponding to the first counter-intuitive behavior.
The anomalous response of elastic-plastic circular plate subjected to various rectangle and triangle impulse loadings is studied. The influences of various loading modes and loading areas on the counter-intuitive behavior of the plate are numerically analyzed in detail. The characteristics of the counter-intuitive behavior under different loadings are obtained. The relation between the number of the displacement peaks in the time-displacement curve and the loading range corresponding to the anomalous response is discovered. The results show that the minimum number of the successive counter-intuitive behaviors can be evaluated from the time-displacement curve corresponding to the first counter-intuitive behavior.
2005, 25(1): 41-46.
doi: 10.11883/1001-1455(2005)01-0041-06
Abstract:
This paper summarizes some test and theoretical results and evaluates several experimental formulas for estimating the penetration and scabbing limit thickness of concrete targets under projectile impact. The parameters of four types of missiles with different characteristics and concrete targets are given. The corresponding penetration and scabbing limit thicknesses are calculated under different velocities. The results indicate that there are minor difference in estimating penetration but significant difference in estimating scabbing limit thicknesses using existing experiential formulas.
This paper summarizes some test and theoretical results and evaluates several experimental formulas for estimating the penetration and scabbing limit thickness of concrete targets under projectile impact. The parameters of four types of missiles with different characteristics and concrete targets are given. The corresponding penetration and scabbing limit thicknesses are calculated under different velocities. The results indicate that there are minor difference in estimating penetration but significant difference in estimating scabbing limit thicknesses using existing experiential formulas.
2005, 25(1): 47-53.
doi: 10.11883/1001-1455(2005)01-0047-07
Abstract:
The hypervelocity impact simulation result is studied about 9.53 mm Al-shpere impacting 2.2 mm Al-target at 6.64 km/s to analyze the macro phenomena. It is shown that the SPH simulations with Steinberg material model and Mie-Grneisen EOS are in accordance with the experimental results. The diameter of the hole initially increases, then slow increases, and finally reaches a stable value. The maximum pressure at the interface between the sphere and the plate is two times higher than aluminium strength. The maximum resistance appears at the moment when the maximum diameter of sphere just intrudes the plate. Debris cloud evolves following self-similar law, and the particles of debris cloud move only inside the so-called evolving cone.
The hypervelocity impact simulation result is studied about 9.53 mm Al-shpere impacting 2.2 mm Al-target at 6.64 km/s to analyze the macro phenomena. It is shown that the SPH simulations with Steinberg material model and Mie-Grneisen EOS are in accordance with the experimental results. The diameter of the hole initially increases, then slow increases, and finally reaches a stable value. The maximum pressure at the interface between the sphere and the plate is two times higher than aluminium strength. The maximum resistance appears at the moment when the maximum diameter of sphere just intrudes the plate. Debris cloud evolves following self-similar law, and the particles of debris cloud move only inside the so-called evolving cone.
2005, 25(1): 54-58.
doi: 10.11883/1001-1455(2005)01-0054-05
Abstract:
The expansion of the blast cavity of de-coupling charge in coal is investigated using the pulse X-radiation photography. The expansion speed and bound of the cavity, the energy transferring factor of shock wave, and the particle velocity at different distances from the blast hole centers are obtained.
The expansion of the blast cavity of de-coupling charge in coal is investigated using the pulse X-radiation photography. The expansion speed and bound of the cavity, the energy transferring factor of shock wave, and the particle velocity at different distances from the blast hole centers are obtained.
2005, 25(1): 59-63.
doi: 10.11883/1001-1455(2005)01-0059-05
Abstract:
Nubbly corundum concrete is a new type defending material, whose anti-penetration characteristics can be affected by many factors. In this paper, the penetration of the nubbly corundum concrete by projectiles with different hit velocity is experimentally studied. The results indicate that the penetration depth does not increase with the increasing hit velocity, which is different from the phenomena of the penetration of concrete and rock. The main reason is that the projectiles are destructed and can not continue to penetrate. Moreover, the higher the hit velocity, the higher anti-penetration capability of the nubbly corundum concrete than that of common concrete or rock.
Nubbly corundum concrete is a new type defending material, whose anti-penetration characteristics can be affected by many factors. In this paper, the penetration of the nubbly corundum concrete by projectiles with different hit velocity is experimentally studied. The results indicate that the penetration depth does not increase with the increasing hit velocity, which is different from the phenomena of the penetration of concrete and rock. The main reason is that the projectiles are destructed and can not continue to penetrate. Moreover, the higher the hit velocity, the higher anti-penetration capability of the nubbly corundum concrete than that of common concrete or rock.
2005, 25(1): 64-68.
doi: 10.11883/1001-1455(2005)01-0064-05
Abstract:
The blasting toe-shooting method is a new technique for soft foundation treatment. The mechanism of blasting toe-shooting method used in mountainous area is studied. Based on the basic theory of soil mechanics and explosive mechanics, the formula of charge weights in relation to the parameters of the charge and the soil is given. Furthermore, the construction techniques and testing method for the blasting toe-shooting method are obtained according to the analytical results and the observed data. The final test results show that the blasting toe-shooting method can satisfy the requirements of the bearing capacity and deformation of embankment foundation.
The blasting toe-shooting method is a new technique for soft foundation treatment. The mechanism of blasting toe-shooting method used in mountainous area is studied. Based on the basic theory of soil mechanics and explosive mechanics, the formula of charge weights in relation to the parameters of the charge and the soil is given. Furthermore, the construction techniques and testing method for the blasting toe-shooting method are obtained according to the analytical results and the observed data. The final test results show that the blasting toe-shooting method can satisfy the requirements of the bearing capacity and deformation of embankment foundation.
2005, 25(1): 70-73.
doi: 10.11883/1001-1455(2005)01-0070-04
Abstract:
Extrusion-cast explosive (ECX) is a new type of composite explosive with high energy and low vulnerability. It can be expected that for ECX wide applications will be found in warhead of high performance weapons. In this work, four ECX with HMX were designed. Cylinder expansion tests of explosives with diameter 25 mm and 50 mm were used to identify the power of ECX formulations with energetic and inert plasticizer. It was found that energetic plasticizer FM-1 had great contribution to the energy of ECX. That is, with the same percentage of HMX (88%), the specific energy of ECX-05 with energetic plasticizer was 22%~23% higher than that of ECX-02 with inert plasticizer, and was better than that of the same type ECX (EX-08-EL) produced abroad. The ability of accelerating metal was close to that of LX-14, i. e., pressed PBX with 95.5% HMX.
Extrusion-cast explosive (ECX) is a new type of composite explosive with high energy and low vulnerability. It can be expected that for ECX wide applications will be found in warhead of high performance weapons. In this work, four ECX with HMX were designed. Cylinder expansion tests of explosives with diameter 25 mm and 50 mm were used to identify the power of ECX formulations with energetic and inert plasticizer. It was found that energetic plasticizer FM-1 had great contribution to the energy of ECX. That is, with the same percentage of HMX (88%), the specific energy of ECX-05 with energetic plasticizer was 22%~23% higher than that of ECX-02 with inert plasticizer, and was better than that of the same type ECX (EX-08-EL) produced abroad. The ability of accelerating metal was close to that of LX-14, i. e., pressed PBX with 95.5% HMX.
2005, 25(1): 74-79.
doi: 10.11883/1001-1455(2005)01-0074-06
Abstract:
The rupture modes of thin metal circular plates struck by conical-nosed missiles were experimentally studied at the critical rupture speeds. The modes of piercing, petalling and plugging appeared respectively with increasing cone half-angles. A failure map was established to distinguish these rupture modes according to the cone half-angle of the missile and the target material properties. In the analysis, the missile tip penetration, the wall deformation and the rupture process in local contact region were also considered. For a missile with cone half-angle 30, the rupture of a thin metal plate was always due to piercing. It was found that there was a critical cone half-angle c=arcsin(exp(－0.5f)) that plugging occured for a missile with ＞c and ＞30, and petalling occurs for a missile with 30＜＜c.
The rupture modes of thin metal circular plates struck by conical-nosed missiles were experimentally studied at the critical rupture speeds. The modes of piercing, petalling and plugging appeared respectively with increasing cone half-angles. A failure map was established to distinguish these rupture modes according to the cone half-angle of the missile and the target material properties. In the analysis, the missile tip penetration, the wall deformation and the rupture process in local contact region were also considered. For a missile with cone half-angle 30, the rupture of a thin metal plate was always due to piercing. It was found that there was a critical cone half-angle c=arcsin(exp(－0.5f)) that plugging occured for a missile with ＞c and ＞30, and petalling occurs for a missile with 30＜＜c.
2005, 25(1): 80-84.
doi: 10.11883/1001-1455(2005)01-0080-05
Abstract:
Dynamic compression experiments on a special steel were carried out using a common SHPB system and a two-specimen SHPB system. The dynamic compression stress-strain curves were obtained for different strain rate history. The effect of strain rate history on the stress-strain curves was investigated through comparing the two stress-strain curves with the same average strain rate but different strain rate history for the same specimen. The results show that the stress-strain curves are significantly affected by the strain rate history, and this effect must be accounted for in the study of material constitutive relations.
Dynamic compression experiments on a special steel were carried out using a common SHPB system and a two-specimen SHPB system. The dynamic compression stress-strain curves were obtained for different strain rate history. The effect of strain rate history on the stress-strain curves was investigated through comparing the two stress-strain curves with the same average strain rate but different strain rate history for the same specimen. The results show that the stress-strain curves are significantly affected by the strain rate history, and this effect must be accounted for in the study of material constitutive relations.
2005, 25(1): 85-89.
doi: 10.11883/1001-1455(2005)01-0085-05
Abstract:
The BPM2D (beam-particle model in two dimensions) was used to simulate the problem of concrete penetration. Three types of beam in the BPM2D were used to create numerical models of concrete. The mechanical properties of each type of beam were randomly allocated according to Weibull distribution to reflect the initial heterogeneity of concrete at the mesoscale level. The failure process of a steel bullet perforating into a concrete panel was analyzed with this model. The comparison of the simulated results with the experimental data and the simulated results of the code LS-DYNA3D demonstrated that the BPM2D was applicable to simulating the dynamic failure problems associated with the transition from continuum to discontinuous media.
The BPM2D (beam-particle model in two dimensions) was used to simulate the problem of concrete penetration. Three types of beam in the BPM2D were used to create numerical models of concrete. The mechanical properties of each type of beam were randomly allocated according to Weibull distribution to reflect the initial heterogeneity of concrete at the mesoscale level. The failure process of a steel bullet perforating into a concrete panel was analyzed with this model. The comparison of the simulated results with the experimental data and the simulated results of the code LS-DYNA3D demonstrated that the BPM2D was applicable to simulating the dynamic failure problems associated with the transition from continuum to discontinuous media.
2005, 25(1): 90-96.
doi: 10.11883/1001-1455(2005)01-0090-07
Abstract:
The dynamic response of simply supporting rigid-plastic circular plate is analyzed using the plastic limit method along with Taylor plate theory. Parameters including maximum residual deformation field are obtained and compared with the FEM results. It is shown that the method is feasible for small deformation and short duration of loading. The influence of fluid-structure interaction and cavatation is also discussed.
The dynamic response of simply supporting rigid-plastic circular plate is analyzed using the plastic limit method along with Taylor plate theory. Parameters including maximum residual deformation field are obtained and compared with the FEM results. It is shown that the method is feasible for small deformation and short duration of loading. The influence of fluid-structure interaction and cavatation is also discussed.
