高压物理学报

Research of Temperature Rise at the Particles Interface Caused by Adiabatic Friction in Explosive Consolidation of Powders

LI Xiao-Jie, WANG Jin-Xiang, ZHANG Yue-Ju, LI Rui-Yong, ZHAO Zheng

2004, 18(2): 97-102 . doi: 10.11858/gywlxb.2004.02.001

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Abstract:
In this paper, a slanting impaction model of two parallel plates was proposed to research the effect of friction between particles during explosive consolidation of powder. The change tendence of the interface friction of the particles with the change of temperature was analyzed, and influence of shock compression, grain size of powders and intensity of material on the time for the holes compaction was researched by LS-DYNA program. A formula to calculate the temperature rise at interface caused by adiabatic friction is given. The result shows that the temperature rise is related to factors of material's characteristics, size of particles, angle of shock-direction and shock compression and so on. The temperature rise decreases with the increase of ability of heat deposit and transfer, and the intensity of material's. It increases as the porosity of material, size of diameter or shock pressure increases. The temperature at the interface can be higher than melting point of the material if the grain diameter and compact force are appropriate.

Experimental Study on the Influence of Device Parameters of FAE to Fuel Dispersion and Explosive Power

HUI Jun-Ming, ZHANG Tao, GUO Xue-Yong

2004, 18(2): 103-108 . doi: 10.11858/gywlxb.2004.02.002

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Abstract:
According to observation results of explosive dispersion process of FAE (fuel-air explosive) test device with fast kinematics analysis system, the different dispersion stages of fuel were characterized and the influence of specific central explosive, ratio of height to diameter and shell material to fuel dispersion was studied in this paper. The results show that dispersion process can be divided into the following three phases, jet formation and expansion movement phase, two-direction expansion movement phase and gas-liquid amalgamation movement phase. The different stages of fuel dispersion process correspond with different hydrodynamics characteristics and contribute to the formation of cloud in respective. Under the conditions of general optimization of test device, cloud area and volume were expanded by properly increasing specific central explosive. The ratio of height to diameter was not a remarkable factor influencing cloud status, but larger ratio of height to diameter dispersed fuel better. Cloud dispersion of steel shell was better than that of aluminum shell. It is concluded that ideal detonation status of cloud and high power effect can be attained when the steel shell, specific central explosive about 3% and ratio of height to diameter between 3 and 5 are adopted and are well-matched of three device parameters above.

Thermal Vinet Equation of State and Its Applications

SUN Jiu-Xun, WU Qiang, CAI Ling-Cang, JING Fu-Qian

2004, 18(2): 109-115 . doi: 10.11858/gywlxb.2004.02.003

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Abstract:
Based on the Einstein model, the universal equation of state for solids proposed by Vinet et al. is extended to include the thermal effect. Employing the nearest neighbor generalized Lennard-Jones potential to describe the effective interaction between the ions, the lattice part of potential energy per atom is expanded as quadratic function of displacement of ion to derive the Einstein temperature and Debye-Grneisen parameter as a function of the volume. The theory contains four potential parameters except for the three parameters in the Vinet EOS, but only five of them are independent, and as the temperature being higher than the Debye temperature, the number of independent parameter can be further reduced to four. The theory is applied for 23 metallic solids, to predict Debye-Grneisen parameters and compressibility coefficients at chamber temperature. The predicted results are in good agreement with the experimental data. The predicted variation of compressibility and thermal expansivity coefficients with temperature for gold, copper, xenon and sodium chloride also are in good agreement with the experimental data.

Numerical Simulation of the Experimental Hypervelocity Launcher

BAI Jing-Song, HUA Jing-Song, Shen Qiang, DAI Cheng-Da, LI Ping, TAN Hua, ZHANG Lian-Meng

2004, 18(2): 116-122 . doi: 10.11858/gywlxb.2004.02.004

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Abstract:
Based on multi-fluid VOF and PPM methods, we develop a MFPPM shock wave physics code to simulate the experiment configuration of the hypervelocity launcher and test the resolution of the algorithms in this code. By using the MFPPM, we simulate some experimental hypervelocity launchers from Sandia National Laboratories, and obtain the numerical results with maximal relative error 1% to 1D, 4.7% to 2D problems compared to that experiments and CTH simulations. Also, a designed model of hypervelocity launcher is simulated too, and some results are given in this paper.

Pressure Calculation for Hot and Dense Gas Mixture

LIU Hui-Ping, YUAN Jian-Min

2004, 18(2): 123-129 . doi: 10.11858/gywlxb.2004.02.005

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Abstract:
Based on the relativistic self-consistent average atom model, the orbital energies and wavefunctions for the bound electrons are calculated by solving the Dirac equations. The average occupation numbers at each orbital and the average ionization degree of each kind of atom are determined by the Fermi-Dirac distribution. The pressure of hot and dense gas mixtures is presented in terms of a quantum free electron gas, a quantum photon gas, and a classical ion gas. The pressure of Al, the mixture of Al and Mg, Fe, and the explosive HMX are calculated at certain temperatures and densities.

Abnormal Phenomenon of Laser-Drilling a Plate Underwater

XU Rong-Qing, CHEN Xiao, SHEN Zhong-Hua, LU Jian, NI Xiao-Wu

2004, 18(2): 130-134 . doi: 10.11858/gywlxb.2004.02.006

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Abstract:
The efficiency of laser-drilling a metal plate in water was observed higher than that in air. A new mechanical sensor based on optical deflection technique was applied to investigate the force acting on a metal in water and air respectively during laser-matter interaction. It is shown that in air the sample is only affected by laser-induced ablation, while underwater it is impacted not only ablation, but also two liquid-jet impulses. Both the amplitude and duration of three forces underwater are much larger than those in air. By scanning electronic microscope, the shape of laser-drilling holes is observed and their different mechanisms in water and air are analyzed in detail.

TEM Analysis of the Phase Transition in the Cold-Rolling Low Carbon Steel under High Pressure

ZHANG Jing-Wu, GOU Hui-Yang, ZHENG Fei, ZHANG Xin-Yu, ZHANG Xiang-Yi

2004, 18(2): 135-138 . doi: 10.11858/gywlxb.2004.02.007

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Abstract:
In this paper we investigate the recrystallization of being cold-rolled low carbon steel under high pressure and analyzes the structure of phase transition under high pressure by TEM technique. It was found that the high pressure can make the recrystallized grains ultrafine; the structure of low carbon steel can change from the body-centred cubic (BCC) to -martensite (HCP) with the increase of high pressure. The lattice constant was calculated based on the electron diffraction pattern.

Research on the Pressure Loss in the Generating Process of Hyperpressure Waterjet

LI Hai-Jun, HE Yuan-Hang, DUAN Zhuo-Ping, ZHANG Qing-Ming

2004, 18(2): 139-143 . doi: 10.11858/gywlxb.2004.02.008

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Abstract:
The pressure loss in the generating process of hyperpressure waterjet is theoretically studied in this paper. The velocities of waterjets have been measured under different conditions. On the basis of theoretical results and the experimental data, the initial parameters of the hyperpressure waterjet have been obtained. The results show that the pressure loss in the generating process is mainly resulted from the section shrinkage. The lost pressure is about 49 percent of the final kinetic energy of hyperpressure waterjet. As the nozzle diameter increases, the pressure loss decreases and the output power of the waterjet generating system is enhanced. As waterjet pressure increases, the pressure loss increases, but the increased degree decreases.

Effect of High Pressure (HP) Treatments on Polyphenoloxidase (PPO) Activity in Pear Juices

ZENG Qing-Mei, PAN Jian, XIE Hui-Ming, YANG Yi, HUANG Xun-Duan

2004, 18(2): 144-148 . doi: 10.11858/gywlxb.2004.02.009

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Abstract:
The effect of high hydrostatic pressure treatment (0.1~500 MPa) combined with mild heat treatment (20~60 ℃) under different pH values (3.0~7.0) on polyphenoloxidase (PPO) activity of Chinese Dangshan pear juice was investigated in this paper. Results showed that the polyphenoloxidase was activated when the high pressure treatment on the pear juice was carried out under the temperature 50 ℃, the dwell time 10 min, the pH5 and the pressure between 200~300 MPa. The polyphenoloxidase activity reached the maximal level under temperature of 30 ℃ synergizing high pressure treatment, and decreased under the temperature of above 30 ℃. The polyphenoloxidase residual activity was rapidly decreased with the increasing of dwell time. The polyphenoloxidase residual activity and the pressureresistance reached their maximal level under pH6.

Simulated Microjet from Free Surface of Aluminum Using Smoothed Particle Hydrodynamics

WANG Pei, QIN Cheng-Sen, ZHANG Shu-Dao, LIU Chao

2004, 18(2): 149-156 . doi: 10.11858/gywlxb.2004.02.010

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Abstract:
Smoothed Particle Hydrodynamics (SPH) is a meshless Lagrangian hydrodynamic computational technique, and the form of SPH equations is simple. An obvious advantage of SPH is that it is meshless, thus large deformation calculations can be easily done with no connectivity complications. In this paper, the dynamic process of microjet from shocked aluminum with grooved surface is simulated with two-dimension SPH code. Jet mass, tip velocity and jet mass mass-velocity were obtained. Numerical results of microjet from grooves with the same depth and different angle are also presented, and compared with experimental ones. It is shown that SPH technique is an effective means for simulating microjet from metal free surface under shock loading.

A Kind of Anodized Aluminium Shock Wave Detectors

SUN Yue, YUAN Chang-Ying, ZHANG Xiu-Lu, WU Guo-Dong

2004, 18(2): 157-162 . doi: 10.11858/gywlxb.2004.02.011

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Abstract:
For making a layer of insulated film, which are both thin, intact, even, compact, and with a higher electric insulating intensity, on a shaped pure aluminium wire (35 mm in length and 1 mm in diameter), we first measured a polarized curve of one half hemispherical end of the aluminium wire based on the anodization principle, and obtained an important technical condition that the aluminium insulated film can be grown steadily in the region of 3 ~13 V at the environment temperature of 50~60 ℃. And then, we confirmed a series of applied operating steps and relevant technical parameters. Therefore, a good experimental recipe, which can be used to direct mass-producing shockwave velocity detectors with a good performance in coherence and reliability, has been determined naturally. At the same time, the influences of temperature condition in electrolysis system and sealing method with boiling water on the film's physical quality and electric insulating intensity were revealed. With the technique, a Al2O3 film of 4~15 m has been made uniformly, which possesses insulating ability of D.C 250 V for 1 min duration. Furthermore, the physical appearance and electric insulating intensity of these detectors are undistinguishable, relative to the original when put them into the liquefied nitrogen for 4 h. The switched on and off consistencies of these probes are measured to be not over 20 ns tested by an impacter forging hammer of 300 Nm. Actually, the performance will be further improved under a higher shock pressure.

A Study of Hypervelocity Impact on 3DBC/SiC Composite Material Dual-Plate Armor

LI Jin-Zhu, HUANG Feng-Lei, ZHANG Qing-Ming

2004, 18(2): 163-169 . doi: 10.11858/gywlxb.2004.02.012

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Abstract:
The dual-plate (or multi-layered) system, first suggested by Whipple in 1940', is a possible means of protecting spacecraft from micrometeoroid impacts. Dual plate armor consists of an outer (bumper) plate, a space, and an inner (catcher) plate. In this work, the bumper plates were SiC ceramic matrix composite reinforced with 3-D braiding fabric (3DBC/SiC) plates, which were comminuted at hypervelocity impacting, resulting in smaller fragments in debris clouds and less damage on catcher plates. Pure aluminum plates and LY12 aluminum plates were also used as bumper plates. But both of them couldn't comminute the projectile and caused severely damage on catcher plates. It is shown that 3DBC/SiC is an ideal material for protecting spacecraft.

Stability of (Mg,Fe)SiO3-Perovskite at Lower Mantle Pressure and Temperature Conditions

ZHANG Li, GONG Zi-Zheng, LIU Hong, DENG Li-Wei, XUE Xue-Dong, JING Fu-Qian

2004, 18(2): 170-176 . doi: 10.11858/gywlxb.2004.02.013

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Abstract:
Shock recovery experiments of (Mg0.92,Fe0.08)SiO3 enstatite were conducted at pressure range from 60 to 110 GPa (the corresponding temperature is estimated as 2 300~4 800 K). X-ray diffraction (XRD) and infrared absorption spectra (IR) of the recovered samples indicate that: (1) The main phase of recovered samples is single-chain structure enstatite, not the perovskite structure; (2) There is no evidence for the existence of oxides SiO2 and (Mg0.92,Fe0.08)O in the recovered samples; (3) After shock compression, some peaks different from original sample were found and these differences are getting more obvious with the increasing of pressure; (4) No obviously different peaks were found between the recovered samples below 85 GPa and those above 97 GPa, from the comparison of XRD and IR spectra among these samples. Combined with the former analysis of experiments of Hugoniot equation of state of enstatite, it was considered that enstatite transformed into perovskite structure under shock compression. The microanalysis requires retrogressive transformation of shocked samples during the process of pressure release. Especially, there is no possibility for the chemical decomposition reaction of (Mg0.92,Fe0.08)SiO3 to oxides SiO2 and (Mg0.92,Fe0.08)O occurring under shock compression, so the high-pressure phase of enstatite－perovskite structure remains stable at the experimental conditions. Meanwhile, we attribute the spectra difference between original sample and recovered samples to a crystal distortion under shock compression or release process and the loading process more probably resulted in such distortion. The results of this investigation provide basic physical evidence for the minerals composition model and the interpretation of seismic wave data for the lower mantle.

The Electrical Conductivity of Pyroxenite at High Temperature and Pressure

WANG Duo-Jun, LI He-Ping, LIU Cong-qiang, YI Li, SU Gen-Li, ZHANG Wei-Gang, XU Zu-Ming

2004, 18(2): 177-182 . doi: 10.11858/gywlxb.2004.02.014

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Abstract:
The electric conductivity of pyroxenite has been measured at pressure of 1.0~2.0 GPa, temperature of 320~700 ℃, and frequency of 105 Hz to 12 Hz, and the conduction mechanism has been analyzed in terms of the impedance spectra. Experimental results indicated that the electric conductivity of pyroxenite depended on the frequency of alternative current. Impedance arcs representing the conduction mechanism of grain interiors are displayed in the complex impedance plane, and this mechanism is dominated at high pressure. The activation enthalpies for pyroxenite are 0.661~0.673 eV. Higher iron content may lead to the higher values of the electrical conductivity in the experiments.

The Numerical Simulation of Solid Liner Implosion in SSS Code

LIU Qi-Tai, SUN Cheng-Wei, HU Xi-Jing

2004, 18(2): 183-187 . doi: 10.11858/gywlxb.2004.02.015

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Abstract:
The SSS code is an one dimensional code for shock and detonation propagations in which the elastic-plastic-hydrodynamic model is used. We modified the pressure boundary condition of SSS code and conducted some numerical simulations for liner implosion experiment. Meanwhile, using the one dimension MHD code, we also conducted the same numerical simulation for the same model. Thinking over the different initial conditions between the two codes, the results are basically consistent. And the consistence between the two codes shows that there is the probability to modify the SSS code as the SSS MHD code.

Measurement of Shock Wavefront Produced by Ejecta Loading Device

ZHENG Xian-Xu, LIU Zhen-Qing, WANG Rong-Bo, LI Zuo-You, YE Yan, ZHONG Jie, LI Ze-Ren

2004, 18(2): 188-192 . doi: 10.11858/gywlxb.2004.02.016

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Abstract:
The shock wavefront produced by ejecta loading device was measured by fiber-pin, and the profile of shock wavefront was acquired by numerical simulation. According to the shape of shock wavefront, the eject time at different point of debris was calculated, and some distribution characteristics of particles ejected from debris surface can be explained by the results.

2004 Vol. 18, No. 2

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