高压物理学报

Determination of the Input Parameters B0K, B0K and 0K for 0 K Universal Isothermal Equation of State

WU Qiang, JING Fu-Qian, LI Xin-Zhu

2005, 19(2): 97-104 . doi: 10.11858/gywlxb.2005.02.001

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Abstract:
A method that is independent of the concrete forms of the isothermal equation of state is proposed to accurately determine the input parameters, which are the isothermal bulk modulus B0K, its first pressure derivative B0K and the specific density 0K at zero pressure and 0 K temperature, directly from the experimental Hugoniot data and without any assumption on the behavior of Grneisen parameter at high pressures and temperatures. Comparisons of these data with ultrasonic experiments demonstrate that the values of B0K, B0K and 0K calculated from this method are rational and of better precision.

A New Conceptual Model to Describe Spallation

CHEN Da-Nian, YU Yu-Ying, YIN Zhi-Hua, LIU Guo-Qing, WANG Huan-Ran, XIE Shu-Gang

2005, 19(2): 105-112 . doi: 10.11858/gywlxb.2005.02.002

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Abstract:
A new conceptual model to describe spallation was presented basing on the original Cochran-Banner spall model. The strength function given by Cochran-Banner was maintained using the redefined damage, and the correction concerning the volume of the mesh cells was realized considering it unnecessary to expect that it is much easier to open microcracks once they are formed than to strain the solid further. Once the spall strength was reached, the damage in the new conceptual spall model would be only determined by a series of closed equations including the stress relaxation relationship given by the strength function, the energy conservation equation, the equation of state, and the constitutive equations for the damaged aggregate. The new conceptual spall model contains only two parameters: the spall strength and the critical damage, the determination of which should make the computed results of spall tests under the appropriate initial and boundary conditions consistent with the experimental free surface velocity profile of target or the stress profile of interface between target and low impedance buffer and the observed damage at spall plane for spall tests. It is worth to note that choosing a strength function or a stress relaxation equation provides a possibility of determining the damage and excludes any extra equation of damage evalution.

Evaluation for Uncertainty of Particle Velocity in Hugoniot Measurements

DAI Cheng-Da, WANG Xiang, TAN Hua

2005, 19(2): 113-119 . doi: 10.11858/gywlxb.2005.02.003

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Abstract:
Uncertainty of particle velocity (u) was systemically analyzed in terms of the general guide to uncertainty evaluation, focusing on two principal types of Hugoniot measurementsflyerplate-impact experiment and relative measurement. The uncertainties of the shock velocity (D), shock pressure (p), compressional density () and compressional specific volume (v) were also formulated in detail based on the law of propagation of uncertainty. For both asymmetric impact (different kinds of sample and driver) and relative measurement, the uncertainty resulted from the approximation of doubleshock Hugoniot or release to the mirror reflection of the principal Hugoniot should be taken into account as Type B evaluation of uncertainty. The situations, such as the obvious difference of the same kind of materials, the temperature rise of the flyer prior to impact and so on, should be avoided in Hugoniot experiments.

Experimental Study on the Process of Fuel Explosive Dispersion

GUO Xue-Yong, HUI Jun-Ming, XIE Li-Feng

2005, 19(2): 120-126 . doi: 10.11858/gywlxb.2005.02.004

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Abstract:
Local records of static explosion were taken by the high-speed video for the 3 kinds of FAE devices. On the analysis of experimental data, the process of fuel explosive dispersion was divided into three regimes: Ejection stage, transition stage and expansion stage, based on the radical expanded velocity caused by explosion acting force and aerodynamic force. For FAE devices with similar structure, according to the experiment data obtained from high-speed video, we got that end-time of different stages and cloud diameters before detonation were proportional to the cube root of fuel quantity, which illuminated that small device can simulate big FAE device. The ratios of cloud diameter to device diameter were 5.5, 30 and 45 at the end moment of different stages, respectively.

An Experimental Study on Shock Response of No-Co Steel

GUI Yu-Lin, WANG Yan-Ping, LIU Cang-Li, SUN Cheng-Wei, ZHANG Ke-Ming

2005, 19(2): 127-131 . doi: 10.11858/gywlxb.2005.02.005

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Abstract:
In this paper, the shock response of no-Co steel is studied, in the impact pressure range from 3 GPa to 20 GPa. The two-wave structural profile of the free surface velocities are recorded by a velocity interferometer system for any reflector (VISAR). Using the material longitudinal elastic wave speed at standard atmosphere instead of the elastic precursor wave speed at low shock pressure, we obtained the Hugoniot relationship between the plastic shock wave speed and the particle velocity for no-Co steel. From the information of the free surface velocity profiles, we also obtained the Hugoniot elastic limit, spall strength, spall thickness.

A Study of Penetration Hole Diameter in Thin Al-Plate by Hypervelocity Impact of Al-Spheres

GUAN Gong-Shun, ZHANG Wei, PANG Bao-Jun, HA Yue

2005, 19(2): 132-138 . doi: 10.11858/gywlxb.2005.02.006

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Abstract:
All spacecraft in low orbit are subjected to hypervelocity impacts by meteoroids and space debris, which can lead to significant damage and catastrophic failure. Investigation into the impact damage characteristics has become an important problem for spacecraft protection designing. In this paper, by experiment and numerical simulation of hypervelocity impact on thin Al-plate by Al-spheres, and it is found that AUTODYN-2D SPH is an effective method of predicting penetration hole diameter in thin Al-plates from hypervelocity impact. By numerical simulation of projectile diameter, projectile velocity and thin Al-plate thickness effect on penetration hole diameter in thin Al-plates from hypervelocity impact, and fitting curves with experiment and simulation results, the law of penetration hole diameter and leading factors affecting penetration hole diameter in thin Al-plates from hypervelocity impact was proposed.

Research on Constitutive Relation of a Polymer Bonded Explosive and Pressed Comp.B

WU Hui-Min, LU Fang-Yun

2005, 19(2): 139-144 . doi: 10.11858/gywlxb.2005.02.007

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Abstract:
Compressive behaviors of a polymer bonded explosive (PBX) and pressed Comp.B have been tested by means of a hydraulic material test machine at different strain-rates. Stress-strain curves of the materials at different strain rates have been obtained in this paper. According to the study on the mechanical behaviors of the two kinds of explosives at different strain-rates, the constitutive relations have been derived, which agree well with the experimental data from quasi-static tests during the linear elastic and strain-hardening stages of the stress-strain curves.

Analysis of Energy Deposition Caused by Micro-Void Collapse in Explosive Consolidation of Powders

WANG Jin-Xiang, LI Xiao-Jie, YAN Hong-Hao

2005, 19(2): 145-150 . doi: 10.11858/gywlxb.2005.02.008

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Abstract:
In this paper, the mechanism of distortion and energy deposition at the interface of the particles in explosive consolidation of powders is analyzed. A one-dimension model of spherical symmetry is used to describe the closure of the micro-holes in powders. Effect of heat conduction is added to the one-dimensional flow equations of spherical symmetry, and the temperature distribution during the closure of the hollow sphere is solved by finite-difference under the condition that the material is rigid-plastic fluid and the constitutive equations are thermo-visco-plastic. The results show that effect of heat conduction becomes more remarkable when the scale of the holes become small; during the closure of the holes the state of the interior surface changes from elastic-plastic to fluid, and its temperature is much higher than other part of the spherical shell.

Numerical Simulations on Buckling Failure of Preloaded Cylindrical Shell Irradiated by High Power Laser Beam

WANG Ji, WANG Xiao-Jun, WANG Feng, ZHAO Kai

2005, 19(2): 151-158 . doi: 10.11858/gywlxb.2005.02.009

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Abstract:
With finite-element software ANSYS 7.0 and simple thermal-mechanical coupling constitutive relations, the buckling failure of preloaded shell irradiated by high power laser beam was studied by numerical simulations. Buckling mode and buckling critical loading were analysed for different preloading conditions. The influences of laser intensity, beam irradiation time, preloading conditions, shape and geometric parameters of shell on the buckling mode were discussed. The numerical results showed that: (1) the buckling deformation of the shell was concentrated on the area of laser spot and the radial buckling was the main buckling mode, (2) a linear relationship between buckling eigenvalue and the maximum temperature at the center of laser spot was approached, (3) the buckling failure of shell was attributed to the coupling effect of the material softenning and the radial deformation in the laser spot, and hence to raise the stiffness of the material would enhance the ability of anti-irradiation of structure substantially, (4) the effect was more obvious under internal preloading for different shapes of shell, and the cylindrical shell had larger buckling eigenvalue and higher security.

Analysis of Interatomic Separation-Pressure Relations for Alkali Halides and Periclase (MgO)

LIU Quan, CHEN Li-Rong

2005, 19(2): 159-163 . doi: 10.11858/gywlxb.2005.02.010

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Abstract:
A new method for the determination of interatomic separation-pressure relations is investigated and applied for alkali halides and MgO crystals. The method is developed by using Hildebrand approximation and an ionic model based on Harrison's treatment of overlap repulsive potential which takes into account the interactions up to second neighbors. The van der Waals dipole-dipole and dipole-quadrupole interactions calculated by more accurate methods are also included in the present work. It is found that the new method yield satisfactory results in agreement with the available experimental data.

Shock Compression Experiments for the Nonyl Phenol Polyethyleneoxy Ether

ZHANG Xiu-Lu, YUAN Chang-Ying, SUN Yue, WEI Jian-Jun, DONG Shi, WU Guo-Dong

2005, 19(2): 164-168 . doi: 10.11858/gywlxb.2005.02.011

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Abstract:
A series of dynamic high pressure loadings to the organic macromolecular emulsion－nonyl phenol polyethyleneoxy ether (C35H64O11) are carried out on a two-stage light gas gun. Within the shock pressure range of 11~42 GPa, seven Hugoniot data of the substance are obtained. The experimental results show that an inflexion is presented on the Hugoniot curve at about 17.8 GPa, which may indicate a complicated phase transition is happened at the high pressure and high temperature.

Numerical Simulation of the Interactions between Hyperpressure Waterjet and Explosive

HE Yuan-Hang, LI Hai-Jun, ZHANG Qing-Ming

2005, 19(2): 169-173 . doi: 10.11858/gywlxb.2005.02.012

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Abstract:
The interactions between the high-speed waterjet of 500 m/s and the condensed explosive have been simulated by LS-DYNA3D code with Lagrange method. The pressure distributions in the explosive at different times and the pressure histories at different elements of the explosive have been calculated. On the basis of numerical simulation, the sound speeds of the explosive have been determined. The numerical simulation results accord with the theoretical analysis. During the process of the interaction between the high-speed waterjet and the condensed explosive, the numerical simulation results show that the pressure decreases with the increase in the radial distance of the element and the maximum pressure occurs nearby or in front of the head of the penetrating waterjet.

Experimental Investigation of the Release Isentropes for OFHC Copper

SONG Ping, CAI Ling-Cang, ZHOU Xian-Ming, TAN Hua

2005, 19(2): 174-178 . doi: 10.11858/gywlxb.2005.02.013

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Abstract:
The release isetropes of oxygen-free copper have been measured by explosive loading technique, in which brass is used as the flyer material, copper as the material both for baseplate and sample, and HR2-steel, SiO2-heavyglass, LY12/LF6 Al, MB2 alloy, PMMA and air as the anvil materials. The results showed the measured release isentropes can be described through Grneisen equation of state with constant approximation in the initial releasing pressure range up to 219 GPa, and the relative deviation, (US-2u)/(2u), of the measured end particle velocity, US, with the value of the mirror-line approximation, 2u, increases with increasing initial releasing pressure.

Influence of Ultra High Pressure on Peroxidase Pectin Methyl Esterase and Soluble Protein in Litchi Fruit

HUANG Li, SUN Yuan-Ming, PAN Ke, CHEN Bai-Nuan, LIANG Di-Wen, CHEN Guo-Lian, YU Hong-Ying

2005, 19(2): 179-183 . doi: 10.11858/gywlxb.2005.02.014

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Abstract:
In order to investigate the effects of ultra high pressure (UHP) on the content of soluble protein, peroxidase (POD) and pectinmethylesterase (PME) in litchi fruit, the pulp of litchi (Litchi chinensis Sonn cv. Huaizhi) was subjected to UHP treatment (100~400 MPa for 30 min at 10 ℃). The activities of POD and PME were detected by spectrophotometry, the isoenzymes of POD and PME were detected by native-PAGE and active staining. The content of soluble protein was detected by SDS-PAGE. Results showed that the POD activity raised and the new isoenzyme appeared when a treatment of 100~200 MPa was applied, the treatment of pressure 300~400 MPa made the POD activity decrease and the new isoenzyme disappear. The PME activity ascended and the new isoenzyme of PME appeared at 100 MPa; when the treatment of 200~400 MPa was applied the PME activity lowered and the new isoenzyme disappeared. The content of soluble protein had a little increase at 100 MPa, but continue to declined at 200~400 MPa.

The Influence of Temperature on Photoemission from Silver Nano-Particles Embedded BaO Thin Film

YANG Hai, HUANG Rui-Qin, ZHANG Tao, ZHOU Shao-Hong, HAO Jian-Ming, MA Yong

2005, 19(2): 184-188 . doi: 10.11858/gywlxb.2005.02.015

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Abstract:
The Dependence of the spectral distribution of photoemission from silver nano-particles embedded in BaO semiconductor thin film on temperature are predicted and investigated theoretically. At high temperature the photoemission response curves to wavelengths from 0.2 to 0.8 m are given. It is showed that the higher temperature, the higher photoemission from silver nano-particles embedded in BaO. An explanation is also presented. It is also pointed out that the critical diameters of silver nano-particles between discrete electron eigenstates (quantum sizes region) and quasicontunuous energy bands for energy band of silver ultra-fine particles in the BaO are less than 3.8 nm.

Density Functional Studies on the Bond Dissociation Energy and Pyrolysis Mechanism of Propyl Nitrate

ZHANG Fang-Pei, CHENG Xin-Lu, LIU Zi-Jiang, HU Dong, LIU Yong-Gang

2005, 19(2): 189-192 . doi: 10.11858/gywlxb.2005.02.016

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Abstract:
The geometry of propyl nitrate was fully optimized using the B3LYP method of density functional theory (DFT) and the standard 6-31G* basis set. The bond dissociation energy of propyl nitrate was calculated. Calculations show that the weakest bond is ONO2 and the less weak bond is CO. The pyrolysis mechanism of propyl nitrate was also discussed, and the products after the cleavage of ONO2 as well as CO had been predicted. In addition, the heat of formation was calculated by ab initio, semi-empirical, and density functional methods, and the result of PM3 is in agreement with the experimental data.

2005 Vol. 19, No. 2

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