2006 Vol. 26, No. 4
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2006, 26(4): 289-293.
doi: 10.11883/1001-1455(2006)04-0289-05
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Abstract:
By applying the smoothed particle hydrodynamics (SPH) method to the detonation driving plate problems, a clear wave structure in the metal plate and the varying process of the projection angle were obtained. According to the projection angle equation, the Taylor formula was modified and the improved Taylor formula was obtained. Comparing the improved Taylor formula and other projection angle formulas, the improved Taylor formula correctly reflected the decreasing process of the projection angle to the final value and could describe the projection angle more accurately.
By applying the smoothed particle hydrodynamics (SPH) method to the detonation driving plate problems, a clear wave structure in the metal plate and the varying process of the projection angle were obtained. According to the projection angle equation, the Taylor formula was modified and the improved Taylor formula was obtained. Comparing the improved Taylor formula and other projection angle formulas, the improved Taylor formula correctly reflected the decreasing process of the projection angle to the final value and could describe the projection angle more accurately.
2006, 26(4): 294-302.
doi: 10.11883/1001-1455(2006)04-0294-09
Abstract:
The present paper studies the perforation of circular metallic plates struck by a blunt rigid projectile with a nose-cabin-column. Effects of transverse shear, bending and membrane deformations on the perforation process are included in a rigid-plastic analysis. Especially the effect of an ahead structural response, induced by the nose-cabin-column impacting the target plate, is considered in the model. Analytical formulae for the perforation ballistic limit and the residual velocity are obtained for a range of plate thickness, which agree with available experimental results on the perforation of metallic plates struck by semi-piercing warheads.
The present paper studies the perforation of circular metallic plates struck by a blunt rigid projectile with a nose-cabin-column. Effects of transverse shear, bending and membrane deformations on the perforation process are included in a rigid-plastic analysis. Especially the effect of an ahead structural response, induced by the nose-cabin-column impacting the target plate, is considered in the model. Analytical formulae for the perforation ballistic limit and the residual velocity are obtained for a range of plate thickness, which agree with available experimental results on the perforation of metallic plates struck by semi-piercing warheads.
2006, 26(4): 303-308.
doi: 10.11883/1001-1455(2006)04-0303-06
Abstract:
A miniature-Hopkinson bar technique, which was used to measure the mechanical behavior of materials at high strain rates, was proposed. For some metals, the strain rate can exceed 104 s-1. The validation of this technique was proven by using laser occlusive radius detector (LORD), and by comparing tests with conventional Hopkinson bar technique. The results show that the strains measured by miniature Hopkinson bar technique have a good agreemant with the strains obtained with LORD. Over the low strain rate ranges, the flow stresses are consistent with that of conventional Hopkinson bar. The miniature Hopkinson bar can be utilized to measure the dynamic behavior of materials at the strain rate beyond 104 s-1.
A miniature-Hopkinson bar technique, which was used to measure the mechanical behavior of materials at high strain rates, was proposed. For some metals, the strain rate can exceed 104 s-1. The validation of this technique was proven by using laser occlusive radius detector (LORD), and by comparing tests with conventional Hopkinson bar technique. The results show that the strains measured by miniature Hopkinson bar technique have a good agreemant with the strains obtained with LORD. Over the low strain rate ranges, the flow stresses are consistent with that of conventional Hopkinson bar. The miniature Hopkinson bar can be utilized to measure the dynamic behavior of materials at the strain rate beyond 104 s-1.
2006, 26(4): 309-314.
doi: 10.11883/1001-1455(2006)04-0309-06
Abstract:
For CV non-Fourier media subjected to high heating rates，an iteration method was proposed for the solution of the coupled thermal-mechanical problem. Two uncoupling problems were computed alternately, and the sufficient precision solution was obtained step by step. These two problems were thermo-stress analysis when temperature was given and the non-Fourier thermal conduction problems when displacement, strain and stresses were provided respectively. The method is adaptable to the Fourier media and independent of the uncoupling problems computing method. The transient response of a Fourier plate was discussed as an application. Results show that the more the times of alternate computing, the more the precision of the result.
For CV non-Fourier media subjected to high heating rates，an iteration method was proposed for the solution of the coupled thermal-mechanical problem. Two uncoupling problems were computed alternately, and the sufficient precision solution was obtained step by step. These two problems were thermo-stress analysis when temperature was given and the non-Fourier thermal conduction problems when displacement, strain and stresses were provided respectively. The method is adaptable to the Fourier media and independent of the uncoupling problems computing method. The transient response of a Fourier plate was discussed as an application. Results show that the more the times of alternate computing, the more the precision of the result.
2006, 26(4): 315-322.
doi: 10.11883/1001-1455(2006)04-0315-08
Abstract:
By using characteristics method of wave propagation, the SHPB tests for the so-called ZWT viscoelastic materials are numerically studied to explore how the basic assumption of uniform distribution of stress along the length of specimen can be satisfied. It is found that the material parameters such as the relaxation time 2 and the transient wave impedance ratio Ri, as well as the rise time of incident wave all strongly influence the stress uniformity, the strain uniformity and the average strain rate of the tested specimen. Results may provide theoretical bases for the design of a dynamic test for viscoelastic material.
By using characteristics method of wave propagation, the SHPB tests for the so-called ZWT viscoelastic materials are numerically studied to explore how the basic assumption of uniform distribution of stress along the length of specimen can be satisfied. It is found that the material parameters such as the relaxation time 2 and the transient wave impedance ratio Ri, as well as the rise time of incident wave all strongly influence the stress uniformity, the strain uniformity and the average strain rate of the tested specimen. Results may provide theoretical bases for the design of a dynamic test for viscoelastic material.
2006, 26(4): 323-327.
doi: 10.11883/1001-1455(2006)04-0323-05
Abstract:
A one-dimensional model was proposed to describe the process of EFP (explosive formed projectile) penetration into a target of finite thickness. The aftereffect prametors and the limit penetrating velocity were calculated with a program based on the proposed model. Numerical results are in agreement with the experimental results.
A one-dimensional model was proposed to describe the process of EFP (explosive formed projectile) penetration into a target of finite thickness. The aftereffect prametors and the limit penetrating velocity were calculated with a program based on the proposed model. Numerical results are in agreement with the experimental results.
2006, 26(4): 328-332.
doi: 10.11883/1001-1455(2006)04-0328-05
Abstract:
By three-dimensional finite element dynamic code LS-DYNA3D, the process of collapse, formation, elongation, instability and break-up of rod-like jet is simulated. The predictions of the simulation are in agreement with experimental data. A acceptable method of numerical simulation and parameters of material are obtained. The process of collapse about rod-like jet is discussed. It may be helpful for designing the configuration of shaped charge of rod-like jet.
By three-dimensional finite element dynamic code LS-DYNA3D, the process of collapse, formation, elongation, instability and break-up of rod-like jet is simulated. The predictions of the simulation are in agreement with experimental data. A acceptable method of numerical simulation and parameters of material are obtained. The process of collapse about rod-like jet is discussed. It may be helpful for designing the configuration of shaped charge of rod-like jet.
2006, 26(4): 333-338.
doi: 10.11883/1001-1455(2006)04-0333-06
Abstract:
To achieve the strength criteria under one-dimensional strain condition for a kind of carbon fiber two-dimensional orthogonal plain woven reinforced polymer matrix composite, formulas were proposed to describe the strain rate-dependent stress-strain relationships in its three principal directions respectively, according to just completed quasistatic and dynamic compression experiments. Then the relationships between strain rate and initial yield strength or compression failure strength for the composite were demonstrated. Based on the results, the strain rate-dependent Tsai-Hill yield and failure criteria under one-dimensional strain condition were achieved. The variation of the Tsai-Hill yield and failure criteria with increasing strain rate was computationally obtained. Results show the strength properties of the researched composite are related to strain rate, and the strain rate effects are anisotropic.
To achieve the strength criteria under one-dimensional strain condition for a kind of carbon fiber two-dimensional orthogonal plain woven reinforced polymer matrix composite, formulas were proposed to describe the strain rate-dependent stress-strain relationships in its three principal directions respectively, according to just completed quasistatic and dynamic compression experiments. Then the relationships between strain rate and initial yield strength or compression failure strength for the composite were demonstrated. Based on the results, the strain rate-dependent Tsai-Hill yield and failure criteria under one-dimensional strain condition were achieved. The variation of the Tsai-Hill yield and failure criteria with increasing strain rate was computationally obtained. Results show the strength properties of the researched composite are related to strain rate, and the strain rate effects are anisotropic.
2006, 26(4): 339-344.
doi: 10.11883/1001-1455(2006)04-0339-06
Abstract:
By comparing the results of Taylor test and computational simulation, a validating and optimizing method on dynamic constitutive model material constants was proposed. This method was applied to the Johnson-Cook model for OFHC copper and some uncertainty of Taylor test was analyzed. Results show that it is reasonable for validating and optimizing material constants for dynamic constitutive model with this method.
By comparing the results of Taylor test and computational simulation, a validating and optimizing method on dynamic constitutive model material constants was proposed. This method was applied to the Johnson-Cook model for OFHC copper and some uncertainty of Taylor test was analyzed. Results show that it is reasonable for validating and optimizing material constants for dynamic constitutive model with this method.
2006, 26(4): 345-350.
doi: 10.11883/1001-1455(2006)04-0345-06
Abstract:
In order to explore the effect of the boundary on the pulsation of underwater explosion bubble, the model of the bubble pulsation dynamics of an underwater explosion was proposed, based on the potential flow theory and considering the effects of proximity of the explosion bubble to a horizontal rigid plane, vertical migration of the bubble due to the hydrostatic imbalance. A computer program was used to solve the model. The pulsation dynamics, the distributing of velocity and pressure in the flow field and the loading of bubble pulsation were analyzed. The results show that the model can correctly describe the dynamic characteristics of the explosion bubble and the liquid around it. Quantificational results can be obtained by solving the model.
In order to explore the effect of the boundary on the pulsation of underwater explosion bubble, the model of the bubble pulsation dynamics of an underwater explosion was proposed, based on the potential flow theory and considering the effects of proximity of the explosion bubble to a horizontal rigid plane, vertical migration of the bubble due to the hydrostatic imbalance. A computer program was used to solve the model. The pulsation dynamics, the distributing of velocity and pressure in the flow field and the loading of bubble pulsation were analyzed. The results show that the model can correctly describe the dynamic characteristics of the explosion bubble and the liquid around it. Quantificational results can be obtained by solving the model.
2006, 26(4): 351-355.
doi: 10.11883/1001-1455(2006)04-0351-05
Abstract:
In order to improve CCD images received from the flash X-ray radiography, a new method called intelligent median-nonlinear diffusion filtering (IMNDF) were proposed based on nonlinear Partial Differential Equation (PDE). This method takes the advantage of both the intelligent median filter and the nonlinear diffusion filter. The numerical results show that the proposed method can eliminate the combination of Gaussian noise and impulse noise efficiently with edge-preserving. The PSNR (promotion of signal-to-noise ratio) of the new method is 3~5 times larger than that of the traditional methods. Well denoised results were obtained for flash X-ray radiographic CCD images.
In order to improve CCD images received from the flash X-ray radiography, a new method called intelligent median-nonlinear diffusion filtering (IMNDF) were proposed based on nonlinear Partial Differential Equation (PDE). This method takes the advantage of both the intelligent median filter and the nonlinear diffusion filter. The numerical results show that the proposed method can eliminate the combination of Gaussian noise and impulse noise efficiently with edge-preserving. The PSNR (promotion of signal-to-noise ratio) of the new method is 3~5 times larger than that of the traditional methods. Well denoised results were obtained for flash X-ray radiographic CCD images.
2006, 26(4): 356-360.
doi: 10.11883/1001-1455(2006)04-0356-05
Abstract:
By explosive powder compaction technics, the WC/Al2O3/Cu particle reinforced metal-matrix composites produced are studied, and the effects of process parameters on density of compacts are analyzed. After investigating the microstructure, densification, tenacity and rigidity properties of composites, it is confirmed that WC/Al2O3/Cu composites can be compacted successfully by explosive compaction.
By explosive powder compaction technics, the WC/Al2O3/Cu particle reinforced metal-matrix composites produced are studied, and the effects of process parameters on density of compacts are analyzed. After investigating the microstructure, densification, tenacity and rigidity properties of composites, it is confirmed that WC/Al2O3/Cu composites can be compacted successfully by explosive compaction.
2006, 26(4): 361-366.
doi: 10.11883/1001-1455(2006)04-0361-06
Abstract:
Pressure response data on the concrete frustum frontispiece were gotten by simulation experiment detonating the aluminized explosives JHL-3, under the conditions of single charge being initiated, and two charges being initiated symmetrically and non-symmetrically respectively. The calculation model of peak pressure was obtained and the diffraction and transmission effects of explosion shock wave on concrete frustum in shallow water were analyzed.
Pressure response data on the concrete frustum frontispiece were gotten by simulation experiment detonating the aluminized explosives JHL-3, under the conditions of single charge being initiated, and two charges being initiated symmetrically and non-symmetrically respectively. The calculation model of peak pressure was obtained and the diffraction and transmission effects of explosion shock wave on concrete frustum in shallow water were analyzed.
2006, 26(4): 367-372.
doi: 10.11883/1001-1455(2006)04-0367-06
Abstract:
In order to estimate the anti-penetrating power of reactive power steel fiber concrete, the deformation and failure model of media is presented according to the relation between state of media and energy distribution in the process of penetration of projectile,and the the scaling relation between near the penetration cavity that energy dissipated and crushing zone is uncovered. Deformation of the medium near the cavity is considered as one-dimension deformation state and similar to hydrokinetics state, accordingly the formulae on of wider applicable confines for calculating penetration is deduced and simplified. And it is considered that the penetration depth is determined by the mass, figure, velocity of the projectile and the strength, density, rupturing temper, deformation wave velocity of the target. The reliability of the formulae is proved by repeated test, and a conclusion is gained that the anti-penetrating ability of RPC is three times as that of general concrete.
In order to estimate the anti-penetrating power of reactive power steel fiber concrete, the deformation and failure model of media is presented according to the relation between state of media and energy distribution in the process of penetration of projectile,and the the scaling relation between near the penetration cavity that energy dissipated and crushing zone is uncovered. Deformation of the medium near the cavity is considered as one-dimension deformation state and similar to hydrokinetics state, accordingly the formulae on of wider applicable confines for calculating penetration is deduced and simplified. And it is considered that the penetration depth is determined by the mass, figure, velocity of the projectile and the strength, density, rupturing temper, deformation wave velocity of the target. The reliability of the formulae is proved by repeated test, and a conclusion is gained that the anti-penetrating ability of RPC is three times as that of general concrete.
2006, 26(4): 373-376.
doi: 10.11883/1001-1455(2006)04-0373-04
Abstract:
By bi-sensitivity VISAR, the shock initiation of JB9014 under divergent spherical shock wave (20 GPa) was experimentally studied. The particle velocity profiles of explosive/window interfaces at different positions were measured. The results show that the run to detonation is within 2~3 mm, and steady detonation is fully developed at 3~5 mm. Preliminary modeling was carried out with hydrocode. The simulation is in accordance with the experimental results.
2006, 26(4): 377-380.
doi: 10.11883/1001-1455(2006)04-0377-04
Abstract:
By scan electric microscope, energy spectroscope, physical observation and chemical dripping, it was found that the deflageration of B/KNO3/RDX produced relatively abundant BN. According to this, a new method of synthesis of BN by the deflageration of energetic materials was proposed. Analyses on the deflageration synthesis principle of BN show that B2O3/NH4NO3 may be an ideal formula for attaining high pure BN.
By scan electric microscope, energy spectroscope, physical observation and chemical dripping, it was found that the deflageration of B/KNO3/RDX produced relatively abundant BN. According to this, a new method of synthesis of BN by the deflageration of energetic materials was proposed. Analyses on the deflageration synthesis principle of BN show that B2O3/NH4NO3 may be an ideal formula for attaining high pure BN.
2006, 26(4): 381-384.
doi: 10.11883/1001-1455(2006)04-0381-04
Abstract:
A method of drop hammer impact sensitivity test for big-bill explosive was developed. The weight of the hammer was 20 kg and the drop height was between 0 ~ 15 m. The size of big-bill explosive was20 mm5 mm and its weight was 2.8 g. Tetryl and JOB-9003 explosives were tested. The threshold heights of ignition for two explosives were 3.5 and 6.5 m respectively. The course of impact for JOB-9003 was simulated. The calculational result well agreed with the test. The test results show this test method can be used to measure the drop hammer impact sensitivity for explosives.
A method of drop hammer impact sensitivity test for big-bill explosive was developed. The weight of the hammer was 20 kg and the drop height was between 0 ~ 15 m. The size of big-bill explosive was20 mm5 mm and its weight was 2.8 g. Tetryl and JOB-9003 explosives were tested. The threshold heights of ignition for two explosives were 3.5 and 6.5 m respectively. The course of impact for JOB-9003 was simulated. The calculational result well agreed with the test. The test results show this test method can be used to measure the drop hammer impact sensitivity for explosives.
