2009 Vol. 29, No. 5
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2009, 29(5): 449-456.
doi: 10.11883/1001-1455(2009)05-0449-08
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Abstract:
In order to explore the failure mechanism of the structures with adhesively-bonded single-lap joints, a Hopkinson tension bar technique was applied to investigate influences of adherent thickness, temperature and velocity (the maximum velocity at the end of the specimen) on the strength of this kind of joint. Experimental results show that the strengths of the specimens tested increase with the increase of the adherent thickness and velocity and the decrease of the temperature. The finite element method was adopted to analyze the stress distribution in the adhesive layer. Analysis displays that shear stress affects the strength of the specimen more dominatingly than peel stress. An influencing factor, which was the value of peel stress divided by shear stress, was introduced to further discuss the effect of peel stress on the strength of the specimen. Further discussions indicate that the effect of peel stress decreases with the increases of adherent thickness and velocity and the decrease of temperature.
In order to explore the failure mechanism of the structures with adhesively-bonded single-lap joints, a Hopkinson tension bar technique was applied to investigate influences of adherent thickness, temperature and velocity (the maximum velocity at the end of the specimen) on the strength of this kind of joint. Experimental results show that the strengths of the specimens tested increase with the increase of the adherent thickness and velocity and the decrease of the temperature. The finite element method was adopted to analyze the stress distribution in the adhesive layer. Analysis displays that shear stress affects the strength of the specimen more dominatingly than peel stress. An influencing factor, which was the value of peel stress divided by shear stress, was introduced to further discuss the effect of peel stress on the strength of the specimen. Further discussions indicate that the effect of peel stress decreases with the increases of adherent thickness and velocity and the decrease of temperature.
2009, 29(5): 457-462.
doi: 10.11883/1001-1455(2009)05-0457-06
Abstract:
A series of model experiments were conducted to explore the failure modes of stiffened plates subjected to underwater explosion. By analyzing the experimental results, three failure modes were established such as Mode I(large plastic deformation),Mode II(tensile failure) and Mode III(shear failure). According to the difference of the load and stiffeners, every failure mode was divided into three sub-modes. And a dimensionless damage factor was proposed to be used as a criterion for predicting the failure modes.
A series of model experiments were conducted to explore the failure modes of stiffened plates subjected to underwater explosion. By analyzing the experimental results, three failure modes were established such as Mode I(large plastic deformation),Mode II(tensile failure) and Mode III(shear failure). According to the difference of the load and stiffeners, every failure mode was divided into three sub-modes. And a dimensionless damage factor was proposed to be used as a criterion for predicting the failure modes.
2009, 29(5): 463-468.
doi: 10.11883/1001-1455(2009)05-0463-05
Abstract:
The 75-mm-diameter split Hopkinson pressure bar (SHPB) technique was applied to experimentally obtain axial or radial stress and strain peaks, average strain rates of different concrete specimens laterally confined by steel sleeves under different impact loads. The damage values of concrete materials were calculated, the damage situations of concrete materials under impact load were described, and the experimental results were analyzed. It is indicated that ductibility and damage resistance of concrete materials increase under passive confining pressure. The failure strains of concrete materials under passive confining pressure is 1.8~2.8 times as large as that in the conventional SHPB experiments.Failure stress is above 150 MPa, which is 2~5 times as large as the static failure stress without passive confining pressure. The result is helpful for the investigation on security protection and failure law of concrete under the lateral confining conditions.
The 75-mm-diameter split Hopkinson pressure bar (SHPB) technique was applied to experimentally obtain axial or radial stress and strain peaks, average strain rates of different concrete specimens laterally confined by steel sleeves under different impact loads. The damage values of concrete materials were calculated, the damage situations of concrete materials under impact load were described, and the experimental results were analyzed. It is indicated that ductibility and damage resistance of concrete materials increase under passive confining pressure. The failure strains of concrete materials under passive confining pressure is 1.8~2.8 times as large as that in the conventional SHPB experiments.Failure stress is above 150 MPa, which is 2~5 times as large as the static failure stress without passive confining pressure. The result is helpful for the investigation on security protection and failure law of concrete under the lateral confining conditions.
2009, 29(5): 468-473.
doi: 10.11883/1001-1455(2009)05-0468-06
Abstract:
Detonation in suspended mixed RDX and aluminum particles in air was numerically simulated with the two-phase flow model. Formation and propagation of detonation was examined and the parameters of detonation were obtained. In calculation the diameter of RDX particle is 20.0 m. Numerical results show that aluminum particles added in high explosive dust can enhance the parameters of detonation waves. As the diameter of aluminum particles is 3.4 m, the ignition distances of two kinds particles are almost the same. As the diameter of aluminum particle is 7.0 m, the ignition distance of aluminum particles is much longer than that of high explosive particles, and a double front detonation can occur in the suspended mixed RDX and aluminum dust.
Detonation in suspended mixed RDX and aluminum particles in air was numerically simulated with the two-phase flow model. Formation and propagation of detonation was examined and the parameters of detonation were obtained. In calculation the diameter of RDX particle is 20.0 m. Numerical results show that aluminum particles added in high explosive dust can enhance the parameters of detonation waves. As the diameter of aluminum particles is 3.4 m, the ignition distances of two kinds particles are almost the same. As the diameter of aluminum particle is 7.0 m, the ignition distance of aluminum particles is much longer than that of high explosive particles, and a double front detonation can occur in the suspended mixed RDX and aluminum dust.
2009, 29(5): 474-480.
doi: 10.11883/1001-1455(2009)05-0474-07
Abstract:
With the theory of stress wave, it discussed mechanism of jointed rock loosing under blasting load. And this was verified by a numerical simulation using the dynamic finite element method. Results show that, compression of blasting load can store strain energy in rocks and quick unloading of the stresses can lead to elastic recovery, which are the essential reason for rock loosing during blast excavation. Blast disturbance can induce rock loosing, typical characteristics are shear moving of rocks in the normal direction of excavation surface and opening of weak planes in the parallel direction. The dynamic finite element method, which adopts Lagrange coordinates, can be used to simulate better the loosing process of jointed rock under blasting load. For example, the program of ANSYS/LS-DYNA is good for this case.
With the theory of stress wave, it discussed mechanism of jointed rock loosing under blasting load. And this was verified by a numerical simulation using the dynamic finite element method. Results show that, compression of blasting load can store strain energy in rocks and quick unloading of the stresses can lead to elastic recovery, which are the essential reason for rock loosing during blast excavation. Blast disturbance can induce rock loosing, typical characteristics are shear moving of rocks in the normal direction of excavation surface and opening of weak planes in the parallel direction. The dynamic finite element method, which adopts Lagrange coordinates, can be used to simulate better the loosing process of jointed rock under blasting load. For example, the program of ANSYS/LS-DYNA is good for this case.
2009, 29(5): 481-485.
doi: 10.11883/1001-1455(2009)05-0481-05
Abstract:
An underwater card gap test method was proposed to measure shock sensitivity of explosives by combining the underwater explosion method and the small card gap test. The shock sensitivity of six explosives, which included PETN, RDX, 8701, Desensitized RDX, TNT, expanded ammonium nitrate explosive, was measured by the proposed underwater card gap test method.The experimental results show that the shock sensitivity of six explosives including PETN, RDX, 8701, Desensitized RDX, TNT and expanded ammonium nitrate get down successively. The results by the underwater card gap test method were compared with the results by the traditional gap test and the results from literatures. Comparison indicates that the experimental results are believable. Furthermore, effect of charge density on shock sensitivity of explosives was investigated by the underwater card gap test method.
An underwater card gap test method was proposed to measure shock sensitivity of explosives by combining the underwater explosion method and the small card gap test. The shock sensitivity of six explosives, which included PETN, RDX, 8701, Desensitized RDX, TNT, expanded ammonium nitrate explosive, was measured by the proposed underwater card gap test method.The experimental results show that the shock sensitivity of six explosives including PETN, RDX, 8701, Desensitized RDX, TNT and expanded ammonium nitrate get down successively. The results by the underwater card gap test method were compared with the results by the traditional gap test and the results from literatures. Comparison indicates that the experimental results are believable. Furthermore, effect of charge density on shock sensitivity of explosives was investigated by the underwater card gap test method.
2009, 29(5): 486-491.
doi: 10.11883/1001-1455(2009)05-0486-06
Abstract:
Equations of motion were analyzed for governing underground explosion-induced stress waves spreading in an elastic domain to explain that this stress wave transmission processes could be described by a time-independent linear system model. According to the impulse response methods in the system identification field, the relationships were established to link the impulse series and source functions in the measured points with the response series. Based on the established relationships, a response model was developed to depict the relevancy between the stress series in the measured points. And a method was introduced to calculate the relevant parameters by adopting the adaptive optimization method of neural network and some important parameters were listed. The relevant response model was validated by the experimental data for a certain chemical explosion in soil. The predictions by the relevant response model are in agreement with the measured data and the relevancy between different measured points is determined only by the distributions of the explosion source, measured points and geological parameters.
Equations of motion were analyzed for governing underground explosion-induced stress waves spreading in an elastic domain to explain that this stress wave transmission processes could be described by a time-independent linear system model. According to the impulse response methods in the system identification field, the relationships were established to link the impulse series and source functions in the measured points with the response series. Based on the established relationships, a response model was developed to depict the relevancy between the stress series in the measured points. And a method was introduced to calculate the relevant parameters by adopting the adaptive optimization method of neural network and some important parameters were listed. The relevant response model was validated by the experimental data for a certain chemical explosion in soil. The predictions by the relevant response model are in agreement with the measured data and the relevancy between different measured points is determined only by the distributions of the explosion source, measured points and geological parameters.
2009, 29(5): 492-496.
doi: 10.11883/1001-1455(2009)05-0492-05
Abstract:
In order to study features of energy distribution for blasting vibration signals, an energy analysis method for blast-induced seismic based on power spectrum is put forward. In some extent, power spectrum density can be regarded as the characterization of relative size of the energy of a certain frequency harmonic. Then a method for calculating the energy-frequency distribution of blasting vibration is derived. Example analysis shows that this method is effective. And the comparative analysis shows that the principle of this method is consistent with the method based on wavelet transform. The method based on power spectrum achieves the transformation from time domain to frequency domain by using spectral analysis. So this method is simple in operation, quite clear in physical meaning, and it can be understood easily.
In order to study features of energy distribution for blasting vibration signals, an energy analysis method for blast-induced seismic based on power spectrum is put forward. In some extent, power spectrum density can be regarded as the characterization of relative size of the energy of a certain frequency harmonic. Then a method for calculating the energy-frequency distribution of blasting vibration is derived. Example analysis shows that this method is effective. And the comparative analysis shows that the principle of this method is consistent with the method based on wavelet transform. The method based on power spectrum achieves the transformation from time domain to frequency domain by using spectral analysis. So this method is simple in operation, quite clear in physical meaning, and it can be understood easily.
2009, 29(5): 497-502.
doi: 10.11883/1001-1455(2009)05-0497-06
Abstract:
A 2-D finite element code was adopted to compute several one-dimensional overdriven shock states of flyer plates impacting on PBX-9501 explosive with the JWL(Tang) equation of state. And the velocities of the flyer plates driven by the explosive were presented. The results of numerical simulation agree well with that of the experiment by Fritz J N, et al. The new equation of state with correction and the adapted code are verified.
A 2-D finite element code was adopted to compute several one-dimensional overdriven shock states of flyer plates impacting on PBX-9501 explosive with the JWL(Tang) equation of state. And the velocities of the flyer plates driven by the explosive were presented. The results of numerical simulation agree well with that of the experiment by Fritz J N, et al. The new equation of state with correction and the adapted code are verified.
2009, 29(5): 503-508.
doi: 10.11883/1001-1455(2009)05-0503-06
Abstract:
Effect of numerical fractures on the computational accuracy is analyzed by introducing artificial numerical fractures. A simple adding-particle technique, which can be easily applied in large deformations, is introduced to prevent numerical fractures. During the adding-particle process, the mass conservation and momentum conservation of the system are kept except that the energy has a little change. The experiments of steel projectile impacting on the airplane skin are simulated by the initial and improved SPH methods. The results show that numerical fractures can lead to very large computational errors. Compared with the initial SPH method, the improved SPH method can prevent numerical fractures effectively. The deformation diameter, the deformation depth and the residual velocity of the projectile obtained by the improved SPH method agree well with the experimental results.
Effect of numerical fractures on the computational accuracy is analyzed by introducing artificial numerical fractures. A simple adding-particle technique, which can be easily applied in large deformations, is introduced to prevent numerical fractures. During the adding-particle process, the mass conservation and momentum conservation of the system are kept except that the energy has a little change. The experiments of steel projectile impacting on the airplane skin are simulated by the initial and improved SPH methods. The results show that numerical fractures can lead to very large computational errors. Compared with the initial SPH method, the improved SPH method can prevent numerical fractures effectively. The deformation diameter, the deformation depth and the residual velocity of the projectile obtained by the improved SPH method agree well with the experimental results.
2009, 29(5): 509-515.
doi: 10.11883/1001-1455(2009)05-0509-07
Abstract:
Regarding a viscous shock wave in a high pressure metal as a strong discontinuity, Miller G H, et al pointed out that a little perturbation shock was unstable under little Reynolds number or large viscosity, and material viscosity was a destabilized factor. Aimed at the conclusion by Miller G H, et al, the linear stability theory was adopted to discuss the stability of normal shock waves in a viscous metal. Regarding a viscous normal shock wave in a high-pressure metal as a continuous profile, this paper points out that any little perturbation shock is stable under any Reynolds number, and material viscosity is a stabilized factor. The error by Miller G H, et al was demonstrated that the boundary conditions from inviscid solutions could lead to the increase of a little perturbation shock. An experimental boundary condition was given to guarantee the stability of a viscous normal shock wave. So a viscous normal shock wave can be regarded as a strong discontinuity, and its stability can be guaranteed.
Regarding a viscous shock wave in a high pressure metal as a strong discontinuity, Miller G H, et al pointed out that a little perturbation shock was unstable under little Reynolds number or large viscosity, and material viscosity was a destabilized factor. Aimed at the conclusion by Miller G H, et al, the linear stability theory was adopted to discuss the stability of normal shock waves in a viscous metal. Regarding a viscous normal shock wave in a high-pressure metal as a continuous profile, this paper points out that any little perturbation shock is stable under any Reynolds number, and material viscosity is a stabilized factor. The error by Miller G H, et al was demonstrated that the boundary conditions from inviscid solutions could lead to the increase of a little perturbation shock. An experimental boundary condition was given to guarantee the stability of a viscous normal shock wave. So a viscous normal shock wave can be regarded as a strong discontinuity, and its stability can be guaranteed.
2009, 29(5): 516-522.
doi: 10.11883/1001-1455(2009)05-0516-07
Abstract:
The slag- and fly ash-based geopolymer concrete (GC) specimens were prepared by sodium silicate and sodium hydroxide alkali-activated slag and fly ash，the ordinary Portland cement concrete (PC) specimens were prepared by Portland cement, the 28-day-static compressive strengths of the GC and PC were 56.4 and 61.6 MPa, respectively. Impact compressive experiments were carried out on the GC and PC specimens, respectively, by using a 100-mm-diameter split Hopkinson pressure bar (SHPB) device.The dynamic stress-strain curves in the average strain rate range of 0 to 100 s-1for these two materials were obtained experimentally. These stress-strain curves were compared to explore the dynamic mechanics properties of the GC. The GC takes on favorable impact compressive strength，deformation performance and toughness under impact load. The GC exhibits rate sensitivity, its dynamic compressive strength, deformation performance and toughness increases with the increase of strain rate under impact load. The impact compressive strength and toughness of the GC are less than those of the PC, the deformation of the GC before the specimens start breaking is approximate to that of the PC, while the deformation of the GC after the specimens break completely is less than that of the PC.
The slag- and fly ash-based geopolymer concrete (GC) specimens were prepared by sodium silicate and sodium hydroxide alkali-activated slag and fly ash，the ordinary Portland cement concrete (PC) specimens were prepared by Portland cement, the 28-day-static compressive strengths of the GC and PC were 56.4 and 61.6 MPa, respectively. Impact compressive experiments were carried out on the GC and PC specimens, respectively, by using a 100-mm-diameter split Hopkinson pressure bar (SHPB) device.The dynamic stress-strain curves in the average strain rate range of 0 to 100 s-1for these two materials were obtained experimentally. These stress-strain curves were compared to explore the dynamic mechanics properties of the GC. The GC takes on favorable impact compressive strength，deformation performance and toughness under impact load. The GC exhibits rate sensitivity, its dynamic compressive strength, deformation performance and toughness increases with the increase of strain rate under impact load. The impact compressive strength and toughness of the GC are less than those of the PC, the deformation of the GC before the specimens start breaking is approximate to that of the PC, while the deformation of the GC after the specimens break completely is less than that of the PC.
2009, 29(5): 523-528.
doi: 10.11883/1001-1455(2009)05-0523-06
Abstract:
Ballistic experiments were performed for Kevlar/Vinyl and E-glass/Vinyl 3D orthogonal woven composites (3D-OWC) impacted by spherical and cylindrical bullets. The results show that the anti-penetration abilities of the targets against spherical bullets are higher than those against cylindrical bullets and the absorption energy per unit area density of Kevlar/Vinyl 3D-OWC is more than that of E-glass/Vinyl 3D-OWC. The major failure mechanisms at the impact sides of the targets are shear and compression failure, but only tension failure can be observed at the back sides of the targets. The z-fibers can improve the in-plane strength of 3D-OWC and the in-plane energy absorption is the major energy absorption mechanism of 3D-OWC.
Ballistic experiments were performed for Kevlar/Vinyl and E-glass/Vinyl 3D orthogonal woven composites (3D-OWC) impacted by spherical and cylindrical bullets. The results show that the anti-penetration abilities of the targets against spherical bullets are higher than those against cylindrical bullets and the absorption energy per unit area density of Kevlar/Vinyl 3D-OWC is more than that of E-glass/Vinyl 3D-OWC. The major failure mechanisms at the impact sides of the targets are shear and compression failure, but only tension failure can be observed at the back sides of the targets. The z-fibers can improve the in-plane strength of 3D-OWC and the in-plane energy absorption is the major energy absorption mechanism of 3D-OWC.
2009, 29(5): 529-534.
doi: 10.11883/1001-1455(2009)05-0529-06
Abstract:
Three groups of emulsion explosives were made of the same emulsion matrix mixed with 2%, 3%, 4% and 5% by the mass of hollow glass microspheres respectively in group 1, and with 2%, 3%, 4% and 5% by the mass of expanded perlite respectively in group two, and with 0.10%, 0.15%, 0.20% and 0.25% by the mass of chemical foaming agent in group 3. The explosion shock waves of all the emulsion explosives in every group were tested in water in two cases that when they were not pressed and after they were compressed by shock waves which were produced by the host charge underwater, and their pressure desensitization degrees were calculated with the peak pressure values of tested shock waves. The pressure desensitization degrees of the emulsion explosives in every group were compared and the influence of their density on the pressure desensitization was analyzed. An emulsion explosive with higher density has a lower pressure desensitization degree.The higher the mass content of expanded perlite or chemical foaming agent mixed with emulsion matrix, the more easily the pressure desensitization of the emulsion explosive occurs.When the mass content of hollow glass microspheres mixed with emulsion matrix increases from 2% to 4%, the pressure desensitization degree of the emulsion explosive increases.But the mass content of hollow glass microspheres mixed with emulsion matrix increases from 4% to 5%, the pressure desensitization degree of the emulsion explosive decreases.Emulsion explosive density influencing its pressure desensitization is mainly due to the emulsion breakage around the density regulator particulates.
Three groups of emulsion explosives were made of the same emulsion matrix mixed with 2%, 3%, 4% and 5% by the mass of hollow glass microspheres respectively in group 1, and with 2%, 3%, 4% and 5% by the mass of expanded perlite respectively in group two, and with 0.10%, 0.15%, 0.20% and 0.25% by the mass of chemical foaming agent in group 3. The explosion shock waves of all the emulsion explosives in every group were tested in water in two cases that when they were not pressed and after they were compressed by shock waves which were produced by the host charge underwater, and their pressure desensitization degrees were calculated with the peak pressure values of tested shock waves. The pressure desensitization degrees of the emulsion explosives in every group were compared and the influence of their density on the pressure desensitization was analyzed. An emulsion explosive with higher density has a lower pressure desensitization degree.The higher the mass content of expanded perlite or chemical foaming agent mixed with emulsion matrix, the more easily the pressure desensitization of the emulsion explosive occurs.When the mass content of hollow glass microspheres mixed with emulsion matrix increases from 2% to 4%, the pressure desensitization degree of the emulsion explosive increases.But the mass content of hollow glass microspheres mixed with emulsion matrix increases from 4% to 5%, the pressure desensitization degree of the emulsion explosive decreases.Emulsion explosive density influencing its pressure desensitization is mainly due to the emulsion breakage around the density regulator particulates.
2009, 29(5): 535-541.
doi: 10.11883/1001-1455(2009)05-0535-07
Abstract:
A finite-difference algorithm linking Euler and Lagrange meshes was developed to compute the cavity-decoupling explosion, in which both the explosion products and ideal air in the cavity were subdivided as Euler mesh but the rock around the cavity was subdivided as Lagrange mesh. The stress wave induced by cavity explosion were simulated and the relations of the seismic source function and the cavity size were discussed. The results show that with the increase of the cavity, the peak stress of the stress wave, the stable value of the seismic source function, and the corner frequency decrease, but the decoupling factor increases.
A finite-difference algorithm linking Euler and Lagrange meshes was developed to compute the cavity-decoupling explosion, in which both the explosion products and ideal air in the cavity were subdivided as Euler mesh but the rock around the cavity was subdivided as Lagrange mesh. The stress wave induced by cavity explosion were simulated and the relations of the seismic source function and the cavity size were discussed. The results show that with the increase of the cavity, the peak stress of the stress wave, the stable value of the seismic source function, and the corner frequency decrease, but the decoupling factor increases.
2009, 29(5): 542-545.
doi: 10.11883/1001-1455(2009)05-0542-04
Abstract:
The split Hopkinson bar technique and the material test system were applied to explore experimentally the mechanical properties of SnAgCu solder at room temperature. The stress-strain curves obtained at different strain rates indicate that SnAgCu solder exhibits a strong strain-rate effect and its plastic hardening moduli have great difference under quasi-static and impact loads. Metallographic analysis shows that the plastic deformation in SnAgCu solder under quasi-static compression is governed by the rotation and deformation of crystal grains, and the dendrite deformation has directivity. While under dynamic compression, the deformation mechanism is distinctly different from that under quasi-static compression, the dendrite as the original phase is no directivity and the primary dendrite arms are broken into secondary dendrite.
The split Hopkinson bar technique and the material test system were applied to explore experimentally the mechanical properties of SnAgCu solder at room temperature. The stress-strain curves obtained at different strain rates indicate that SnAgCu solder exhibits a strong strain-rate effect and its plastic hardening moduli have great difference under quasi-static and impact loads. Metallographic analysis shows that the plastic deformation in SnAgCu solder under quasi-static compression is governed by the rotation and deformation of crystal grains, and the dendrite deformation has directivity. While under dynamic compression, the deformation mechanism is distinctly different from that under quasi-static compression, the dendrite as the original phase is no directivity and the primary dendrite arms are broken into secondary dendrite.
2009, 29(5): 546-549.
doi: 10.11883/1001-1455(2009)05-0546-04
Abstract:
A new setup was designed for dynamic tension of metal ring. The line initiation by exploding wire was used in the designed setup. The dynamic tensile experiments of OFHC copper rings at high strain rate were carried out by the designed setup. The radial velocity histories of OFHC copper rings were measured by a laser displacement interferometer. The stress-strain-rate relations for OFHC copper were obtained by processing the radial velocity histories of OFHC copper rings.
A new setup was designed for dynamic tension of metal ring. The line initiation by exploding wire was used in the designed setup. The dynamic tensile experiments of OFHC copper rings at high strain rate were carried out by the designed setup. The radial velocity histories of OFHC copper rings were measured by a laser displacement interferometer. The stress-strain-rate relations for OFHC copper were obtained by processing the radial velocity histories of OFHC copper rings.
2009, 29(5): 550-554.
doi: 10.11883/1001-1455(2009)05-0550-05
Abstract:
Submicron -CL-20 particles with the mean particle diameter of 721.9 nm were prepared by the gas antisolvent technology and were confirmed by the SEM results. Polymorphs of submicron -CL-20 were identified by FT-IR spectroscopy. Small-scale gap tests were performed for submicron -CL-20, and its impact sensitivity and ignition temperature were measured. The gap thickness decreases 58.6% and the characteristic droop is higher 84.1% than that of the raw material, while the ignition temperature with 5 s delay is the same as that of the raw material.
Submicron -CL-20 particles with the mean particle diameter of 721.9 nm were prepared by the gas antisolvent technology and were confirmed by the SEM results. Polymorphs of submicron -CL-20 were identified by FT-IR spectroscopy. Small-scale gap tests were performed for submicron -CL-20, and its impact sensitivity and ignition temperature were measured. The gap thickness decreases 58.6% and the characteristic droop is higher 84.1% than that of the raw material, while the ignition temperature with 5 s delay is the same as that of the raw material.
2009, 29(5): 555-560.
doi: 10.11883/1001-1455(2009)05-0555-06
Abstract:
This paper studied the analysis and processing method for the measured penetration deceleration data, proposed a new method which combining the modal analysis of the test projectile and test equipment with spectrum analysis of the measured data, and obtained corresponding penetration deceleration of the rigid body by selecting low pass cutoff frequency to filter the measured data. The obtained penetration deceleration of the rigid body determined from the measured data by the method presented in this paper shows a good agreement with the calculated results by the cylindrical cavity expansion theory,and the projectile penetration velocity and displacement obtained from integrating the penetration deceleration of the rigid body after filtering also shows a good agreement with the measured results.
This paper studied the analysis and processing method for the measured penetration deceleration data, proposed a new method which combining the modal analysis of the test projectile and test equipment with spectrum analysis of the measured data, and obtained corresponding penetration deceleration of the rigid body by selecting low pass cutoff frequency to filter the measured data. The obtained penetration deceleration of the rigid body determined from the measured data by the method presented in this paper shows a good agreement with the calculated results by the cylindrical cavity expansion theory,and the projectile penetration velocity and displacement obtained from integrating the penetration deceleration of the rigid body after filtering also shows a good agreement with the measured results.
