高压物理学报

Theoretical Calculation for the Hugoniot Curves of Liquid Nitrogen

YANG Xiang-Dong, XIE Wen, WU Bao-Jian, HU Dong, JING Fu-Qian

1998, 12(1): 1-7 . doi: 10.11858/gywlxb.1998.01.001

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Abstract:
The shock compression properties of liquid nitrogen are studied by means of the improved WCA theory considering the soft-sphere correlation. The excess free energy is calculated using the six exponent potential and Ross' variational fluid perturbation theory. Our theoretical Hugoniot curves agree with the experimental data.

Research on Errors in Situ of Magnetic Measurement in High Hydrostatic Pressure Vessel－(1) The Influence of Leakage Flux

SU Fang

1998, 12(1): 8-16 . doi: 10.11858/gywlxb.1998.01.002

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Abstract:
In order to research the influence of leakage flux in high hydrostatic pressure vessel, we have measured the magnetization curve under five different ambient conditions, then compared the B-H curve measured on table far from iron with B-H curve measured in situ in pressure vessel. Finally we calculated the relative errors, c0/c0, produced by leakage flux of electric solenoid with 13 layers in pressure vessel. The results show that (1) for empty secondary coil, c0/c0=-1.90%～-1.27% (400 Hz), -0.36%～-0.64% (1 000 Hz); (2) for Fe nanometer-scale powder, magnetization curve and initial B-H curve are all straight lines, i.e. both of them possess constant magnetic permeability, . Relative errors produced by leakage flux in high pressure vessel, /=3.9%～3.8%, about one time higher than that of (1).

Study on Thermal Stability of Nanotubes under High Pressure

ZHANG Ming, HE Duan-Wei, ZHANG Xiang-Yi, XU Ying-Fan, WANG Wen-Kui, LIANG Ji, WEI Bing-Qing, WU De-Hai

1998, 12(1): 17-21 . doi: 10.11858/gywlxb.1998.01.003

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Abstract:
In this paper, the thermal stability of nanotubes under 5.5 GPa was studied by X-ray diffraction and transmission electron microscopy. According to previous research results, at high vacuum and ambient pressure, the structure of nanotubes will be kept below temperature of 3 000 K. However, in our study, its structure begin to change at only 950 ℃ under 5.5 GPa; and the nanotubes will transform into graphite at 1 150 ℃. High pressure may be contributed to the transformation. High pressure may promote nanotubes transform into graphite, and decrease thermal stability.

Properties of Solid Hydrogen at High Pressure

CUI Tian, ZOU Guang-Tian, HAN Jie, Whaley K B

1998, 12(1): 22-27 . doi: 10.11858/gywlxb.1998.01.004

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Abstract:
The path integral Monte Carlo method with a constant pressure ensemble is used to study the equation of state of solid hydrogen with translational and rotational degrees of freedom. The results are in quantitative agreement with the experimental data. For understanding the quantum nature of the solid, the energies of the system at different temperatures are also calculated.

Equation of State of Liquid CO2 at High Temperature and High Densities

LIU Fu-Sheng, CHEN Xian-Meng, CHEN Pan-Sen, SUN Yue, JING Fu-Qian

1998, 12(1): 28-33 . doi: 10.11858/gywlxb.1998.01.005

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Abstract:
In this work the shock compression behavior of liquid CO2 is investigated using the two-stage light-gas gun and the cryogenic target established by ourselves. Six new Hugoniot data ranging from 20～60 GPa are obtained. On the basis of these data points, the parameters in the effective potentials of　CO2-CO2 and CO2-O are re-determined according to a statistical mechanics theory including chemical equilibrium. The significant mechanism which causes the p-V softening phenomena above 25 GPa is theoretically confirmed to be CO2CO+O.

Experiments of Needle-Like Diamond Synthesis and Its Formation Mechanism

LIU Qiang, LUO Xiang-Jie, DING Li-Ye

1998, 12(1): 34-39 . doi: 10.11858/gywlxb.1998.01.006

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Abstract:
The regular needle-like diamond were synthesized in the FeFe55Ni29Co16+B4C system at high temperature and high pressure conditions of 1 470 ℃ and 5.9 GPa, which are seldom seen in the experiments of diamond synthesis. The Fe55Ni29Co16+B4C system is compared with the Ni70Mn25Co5+B4C system and the cause of the formation of needle-like diamond is discussed in this paper. The theoretical analyses in the paper provide a possible approach for synthesizing needle-like diamond for practical use.

Simulation of Shock Compression Behavior of Mixture by Using the Finite Element Method

LIN Hua-Ling

1998, 12(1): 40-46 . doi: 10.11858/gywlxb.1998.01.007

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Abstract:
In this paper, the shock compression behavior of mixture is simulated by using a three-dimensional finite element code. The mixture is as a randomly distributed component grains in space. As an example, the mixture composed of copper and aluminum is calculated and the result is compared with the superposition principle. They are in accord with each other.

Applying Genetic Algorithm to Determine Parameters in Equation of State

JIANG Hou-Man, ZHANG Ruo-Qi, ZHANG Shou-Qi

1998, 12(1): 47-53 . doi: 10.11858/gywlxb.1998.01.008

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Abstract:
Genetic algorithms (GA), emulating the wonderful mechanism of evolution and natural selection of living organisms in nature, are regarded to be among the most promising optimization techniques. In this paper, a genetic algorithm was implemented to decide the target Grneisen-Hugoniot EOS parameters, using the stress history recorded with a Lagrangian gauge in a plane impact experiment. The results are in good agreement with the corresponding actual values. Comparison is made between the optimized results using GA and those obtained using BFGS with different initial iteration points.

Measurement of Grneisen Parameter of Aluminum at High Pressure

WANG Zhu-Ming, XIE Hong-Sen, GUO Jie, XU Ji-An

1998, 12(1): 54-59 . doi: 10.11858/gywlxb.1998.01.009

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Abstract:
Using a quasi-adiabatic method, and measuring the temperature change in the compressive process, we can directly determine the Grneisen parameter in various materials. In the world, only one laboratory had performed such a technique in the high pressure system in which the liquid transmit medium was used. In the present work, we report the results of determination of the Grneisen parameters of Al up to 3.5 GPa. It is the first time to carry out such a measurement in a high pressure system with solid pressure transmission medium.

The Heat Treatment of the Residual Stress Relieved for Explosive Welded Stainless Steel/Carbon Steel Cladded Plate

WANG Zhi-Ping, HE Zhi, LI Qiang, GAO Guo-Qing

1998, 12(1): 60-66 . doi: 10.11858/gywlxb.1998.01.010

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Abstract:
The heat treatment of explosive welded stainless steel/carbon steel cladded plates was conducted in order to relieve the residual stress near the welded interface. The mechanical performances of the samples and the microhardness curves of both sides of interface were measured. The compositions of both sides near the interface were analyzed by the scanning electron microscope and the metalloscopy. The results indicate that whether the sample is heat-treated or not, the compositions of both sides of the interface are diffused each other; When the heat-treated temperature below 550 ℃, the mechanical properties and hardness of the samples do not change much. When the temperature above 650 ℃, the hardness reduces but the decarburization of carbon steel in taken placed. At 750 ℃, the phase change is taken place in the carbon steel. Consequently, the optimum heat-treated temperature is possibly 600 ℃.

Experimental Research for Penetration of Simulated Projectile into Concrete Targets

ZENG Jian-Rong, LIU Gao-Min, WEN Dian-Ying, LIU Quan-Zhong

1998, 12(1): 67-71 . doi: 10.11858/gywlxb.1998.01.011

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Abstract:
For three projectiles which size are reduced in proportion, the impact velocities and penetration process were measured and photographed by using the technique of electric probe and framing camera. The maxima of penetration depth corresponding to each impact velocity have been obtained, and through analyzing these data, an experiential formula for predicting the maximal penetration depth is developed, results show the data calculated from the formula are in good agreement not only with that of our experiments, but also with that in the reference.

Shock Hugoniot Relation of JB-9001 Insensitive High Explosive

YU Chuan, CHI Jia-Chun, LIU Wen-Han, LI Liang-Zhong, YANG Shu-Ying

1998, 12(1): 72-77 . doi: 10.11858/gywlxb.1998.01.012

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Abstract:
Shock Hugoniot relation is the basic characteristic parameters of explosive. JB-9001 is a plastic bonded explosive which mainly contains TATB. JB-9001 explosive and standard material LY12 samples were processed and their sizes are same. Two samples are symmetrically put on the LY12 base plate. One dimensional detonation loading system consists of detonator, initiation charge, plane wave generator and main charge. The LY12 flyer is driven by detonation wave which is attenuated with a metal plate. We use manganin gauges and oscilloscope to record the interface pressure pexp and pAl between the LY12 base plate and the explosive sample as well as between the LY12 plate and LY12 sample. Since the shock Hugoniot relation of LY12 is known, we can determine a reflected shock Hugoniot relation curve on the Hugoniot diagram by measuring the interface pressure pAl. On the basis of the shock wave formula and boundary conditions, the shock wave velocity us and the particle velocity up behind the wave are derived. We have obtained the shock Hugoniot relation of JB-9001 explosive with average density 0=1.875 g/cm3 by using least square method us=(2.780.21)+(1.430.19)up (0.40 km/sup1.51 km/s) experimental measuring error is less than 5%.

1998 Vol. 12, No. 1

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