高压物理学报

Experimental Study of Methane Hydrate Prepared through Reaction of Al4C3 with H2O

LI Wen-Qiang, KOU Zi-Li, LI Wen-Yong, WANG Zhao, ZHANG Wei, HE Duan-Wei

2011, 25(4): 289-295 . doi: 10.11858/gywlxb.2011.04.001

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Abstract:
Methane hydrate is successfully prepared through the reaction of Al4C3 and H2O using a laboratory designed high pressure hydrate apparatus. Experimental results indicate that this method is an effective solution to introduce CH4 in the synthetic experiments of methane hydrates, and the pressure-temperature formation conditions of the methane hydrate approach the natural situation. In addition, the products of the reaction of Al4C3 and H2O can simulate the real formation process of methane hydrate in the ocean environment and offer an effective route to natural gas hydrate research. With this method, a preliminary study is presented concerning the formation, dissociation and dynamic processes of methane hydrate under different temperature and pressure conditions.

A System for Measuring Two-Stage Light Gas Gun Projectile Velocity with Laser Screen and Photodetector

DENG Yun-Fei, ZHANG Wei, JIA Bin, PANG Bao-Jun, CAO Zong-Sheng

2011, 25(4): 296-302 . doi: 10.11858/gywlxb.2011.04.002

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Abstract:
A new velocity measurement system is set up for measuring the millimetresized projectile velocity in two-stage light gas gun. The system consists of an installation platform and a laser velocimeter which using red light semiconductor laser as lamp-house and silicon photodiode as photodetector. The platform installed in the barrel test section has numerous advantages of simple structure, aseismic design, easy adjustment and measurement. Using this new measurement system, the metallic and non-metallic projectiles velocities are successfully achieved. Moreover, the velocities of metallic projectile measured by this system are compared with those using magnetic induction sensors. The results show that this system not only has high reliability and accuracy but also high sensitivity, strong anti-interference and wide range of applications.

Use and Pressure Calibration of 1 000 Tons Walker Module High Pressure and High Temperature Apparatus

YANG Bin, LU Feng-Guo, ZHAO Xu-Dong, LIU Xiao-Yang

2011, 25(4): 303-309 . doi: 10.11858/gywlxb.2011.04.003

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Abstract:
The two-stage 1 000 tons Walker module large-volume high temperature and high pressure apparatus can generate different pressures with different truncated edge lengths of anvils (12, 8, 6, and 4 mm). If tungsten carbide is chosen as an anvil, the maximum pressure obtained is above 20 GPa. The sample assemblies of Walker module apparatus are determined. The pressure calibration is performed by the fixed points of phase transitions method for different truncated edge lengths. The phase transition pressures of standard materials of pressure calibration (Bi, Tl, ZnTe, Pb, ZnS, GaAs) are achieved by measuring the resistance change with oil load under high pressure. The calibration curve of the sample pressure versus load is obtained, which provides exact information for future high pressure experiments using this apparatus.

A Novel Strain Type High Chamber Pressure Test System

LI Xin-E, ZU Jing, XU Peng

2011, 25(4): 310-316 . doi: 10.11858/gywlxb.2011.04.004

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Abstract:
According to the characteristics of electronic piezo gauge, a novel strain type high chamber pressure test system is developed, which takes the end cover of the electronic piezo gauge as an elastic sensitive component. The mechanical characteristics of electronic piezo gauge shell are analyzed using the deformation theory of thick plates. The stress/strain distribution and model of the elastic sensitive components are simulated by ANSYS software, and the 50-550 MPa static and dynamic calibration experiments are also conducted for comparison. The experimental results show that the linear error, basic error, sensitivity, and measurement range of the system are 0.62%, 4.6%, 2.231 310-12 Pa-1, and 0-600 MPa, respectively. Therefore, the strain type high chamber pressure test system is feasible and accurate.

Thermoelectric Properties of AgSbTe2-Sb2Te3 Prepared by High Pressure Synthesis

SU Tai-Chao, ZHANG Shu-Guang, LI Xiao-Lei, MA Hong-An, LI Shang-Sheng, JIA Xiao-Peng, 

2011, 25(4): 317-320 . doi: 10.11858/gywlxb.2011.04.005

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Abstract:
The p-type thermoelectric materials of AgSbTe2 alloyed with Sb2Te3 ((AgSbTe2)1-x(Sb2Te3)x, 0x0.3) are prepared by high pressure method. The structure and thermoelectric properties of (AgSbTe2)1-x(Sb2Te3)x are studied at room temperature. Experimental results indicate that the samples are near single phase AgSbTe2 when x0.1. The electrical resistivity of the sample decreases dramatically with the increasing of synthetic pressure and Sb2Te3 content x. The Seebeck coefficient increases. The high pressure combining with Sb2Te3 doping can improve the power factor of AgSbTe2 effectively. Moreover, the enhanced power factor reaches 10.4 W/(cmK2), and the high figure of merit reaches 0.466 for (AgSbTe2)0.9(Sb2Te3)0.1 prepared at 2.0 GPa, which is close to that of Bi2Te3.

Yield Strength Analysis of Tantalum in Quasi-Isentropic Compression

ZHANG Hong-Ping, WANG Gui-Ji, LI Mu, ZHAO Jian-Heng, SUN Cheng-Wei, TAN Fu-Li, MO Jian-Jun, ZHU Wen-Jun

2011, 25(4): 321-326 . doi: 10.11858/gywlxb.2011.04.006

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Abstract:
For analyzing the quasi-isentropic compression experimental data of solid materials, a backward integration method with strength effect is presented based on rate-dependent constitutive equation and fluid elastic-plastic model. From the quasi-isentropic compression data of tantalum on CQ-1.5 with a loading time of 700 ns, the yield strength, deviatoric stress and interior information of the tantalum sample are calculated. Moreover, the Lagrangian sound speed and strain rate are also analyzed. As a result, the driving history and stress distribution of the tantalum sample are obtained. It is found that the yield strength of 1.85 GPa corresponds to the peak stress (30 GPa) with strain rates of 10 5 s-1, and the isentropic elastic limit is about 2.9 GPa. Numerical results show that the calculated stress-strain and pressure-volume curves appear to be in good agreement with the experimental data from Sandia National Laboratory.

Study on Effect Mechanism of Aspect Ratio for Vertical Penetration of a Long-Rod Projectile

GAO Guang-Fa, LI Yong-Chi, HUANG Rui-Yuan, DUAN Shi-Wei

2011, 25(4): 327-332 . doi: 10.11858/gywlxb.2011.04.007

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Abstract:
The penetration depth is analyzed for a long-rod projectile penetrating semi-infinite target using dimensional theory. Combining numerical simulation and empirical formula studies, the effect mechanism of aspect ratio is systematically investigated. The results show that the normalized energy density consumption by penetration depth increases as increasing of aspect ratio when the penetration efficiency does not change. For the long-rod penetrators with same volume, the penetration depth increases with the increasing of aspect ratio until reaches a maximum value. The main reason of this phenomenon is due to the funnel-shaped crater and high-temperature generated in subsequent unstable stage of penetration. The interface resistance effect has strong influence on the penetration depth, but which has no apparent connection with the aspect ratio of penetrator.

Equation of Penetration and Crater Growth by Shaped Charge Jet under the Influence of Shock Wave

XIAO Qiang-Qiang, HUANG Zheng-Xiang, GU Xiao-Hui

2011, 25(4): 333-338 . doi: 10.11858/gywlxb.2011.04.008

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Abstract:
When the penetration velocity is greater than the sound speed, a shock wave will be formed which leads the state parameters of the material change after shock wave front. As the shock wave affects the process of jet penetration and crater growth, Bernoulli equation can not be used directly across shock wave front. On the basis of considering the influence of shock wave during jet penetration, the mechanical properties of axial penetration and radial crater growth are analyzed in the process of shaped charge jet penetration, and the propagation and strength degradation of shock wave are assumed. The penetration model is established for the two cases of the penetration velocities greater or less than the sound speed of target respectively and a new equation of shaped charge jet penetration and radial crater growth is proposed. Compared with Szendrei-Held model, the results show that this model is more suitable for the experimental data of Held et al. Moreover, the influence of shock wave on axial penetration is much smaller than that on the radial crater growth.

Penetration Analysis of a Rod-Shaped Projectile in Semi-Infinite Target

JIANG Jian-Sheng, WANG Zheng, LIANG Long-He, HONG Tao

2011, 25(4): 339-343 . doi: 10.11858/gywlxb.2011.04.009

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Abstract:
When analyzing the penetration of a rod-shaped projectile in semi-infinite target, the velocity gradient of the shaped charge jet is taken into account. The jet is divided into a series of segments, and the variations of the length and diameter of each jet segment are calculated at the moment of impacting on the target. Through the Bernoulli equation, linear approximations of velocity and diameter of the jet, and static method, the relationship between penetration depth and hole diameter in the target and impacting jet is obtained. Moreover, the simulated results are in quite good agreement with the experimental data.

Temperature Change and Microstructure Evolution of the Bore Penetrated by Copper Jets

CHEN Hao, TAO Gang

2011, 25(4): 344-350 . doi: 10.11858/gywlxb.2011.04.010

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Abstract:
After metal jets penetrate the steel target, the jets' material adheres on the penetration channel wall. The research on the jets' material is helpful to analyzing the dynamic superplastic deformation and morphological changes of jets in the process of penetration and cooling. Theoretical computation and numerical simulation are used in this work to study the penetration process of copper jets, and the changes of temperature and grain size of copper jets adhered on the penetration channel wall are obtained. The simulated results are in good agreement with the SEM (Scanning Electron Microscope) observation. From the observation of microstructure of copper and steel, we can get the conclusion that the copper jets do not melt but instead undergo dynamic recrystallization in the process of penetration. In addition, the copper grain size increases obviously and the twins are formed in the cooling process.

Conditions Analysis of Laser-Driven Plasma Jet

LI Mu, SUN Cheng-Wei, ZHAO Jian-Heng, LUO Zhen-Xiong, ZHONG Jie

2011, 25(4): 351-358 . doi: 10.11858/gywlxb.2011.04.011

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Abstract:
Laser-driven plasma jets provide a new way to simulate astrophysical jets and generate shockless loading in solids to high pressures, which are very important in the researches of high energy density physics. The experiments are all under the conditions with very high laser intensity in literatures, but there is no criterion of the basic condition under which the plasma jets can form from the rear surface of the driven film. The main objective of the current study is to investigate the effects of laser intensity, wavelength, pulse width, target material, and target thickness on plasma jet using analytic numerical methods. The results show that the shock strength before exiting the rear of the reservoir must be higher than a threshold value for jet formation. For polyethylene, this value is about 80 GPa. The lower wavelength, boiling temperature, and ionization threshold value, and higher laser intensity, longer pulse width, thinner target, the plasma jet is more easily achieved for the thin target with low boiling temperature and small ionization threshold value when irradiated by a pulsed laser with high intensity, short wavelength and long pulse width.

Experimental Research of Deflagration to Detonation Transition of Epoxypropane-Aluminum-Air Mixtures in Large-Scale Tube

CHEN Mo, BAI Chun-Hua, LIU Qing-Ming

2011, 25(4): 359-364 . doi: 10.11858/gywlxb.2011.04.012

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Abstract:
Motivated by the current interest in the mechanism of the deflagration to detonation transition (DDT), the DDT experiments of epoxypropane-air mixture and epoxypropane-aluminum-air mixture are carried out by a large-scale tube (32.4 m long and 0.199 inner diameter). The processes of DDT in multi-phase clouds are analyzed, and the mixtures with different concentrations are compared. The self-sustained detonation waves are formed in the epoxypropane-air mixture with epoxypropane concentration of 513 g/m3 and epoxypropane-aluminum-air mixture with epoxypropane and aluminum concentrations of 237 and 643 g/m3, and moreover the cell size of the detonation are 0.28 and 0.5 m, respectively.

Calculation and Experiment of Overdriven Detonation Parameters of C2H2-O2 Mixture

WANG Jian, DUAN Ji-Yuan, HUANG Wen-Bin, ZHAO Ji-Bo, WEN Shang-Gang, TAN Duo-Wang

2011, 25(4): 365-369 . doi: 10.11858/gywlxb.2011.04.013

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Abstract:
Based on the C-J theory and polytropic gas equation of state, a simple physical model is developed to calculate the parameters of overdriven detonation wave for C2H2-O2 mixture with a stoichiometric ratio. The overdriven detonation experiments are also performed in a shock tube using a high speed digital camera and six piezoelectric sensors. The calculated overdriven detonation velocity is in agreement with the experimental value. Therefore, the overdriven detonation parameters obtained by this method are feasible and effective.

Numerical Simulation of the Response of Reinforced Concrete Slabs to Projectile Impact or Explosive Loading

MENG Yang, WEN He-Ming

2011, 25(4): 370-378 . doi: 10.11858/gywlxb.2011.04.014

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Abstract:
Numerical simulation is first conducted herein of the perforation of reinforced concrete slabs by an ogival-nosed projectile using LS-DYNA. The triaxial test data reported in this paper for the 48 MPa concrete are used to determine the values of the parameters employed in the Holmquist-Johnson-Cook (HJC) model. It is shown that the numerical simulations correlate well with the experimental observations in terms of ballistic limit, residual velocity, impact crater, penetration tunnel and scabbing crater. The response of reinforced concrete slabs to explosive loading is also studied numerically by the fluidsolid coupled method of LS-DYNA. The simulation reproduces the transient process of the shock wave and the main rupture process of the slabs. The numerically obtained pressure-time histories are found to be in reasonable agreement with those predicted by the empirical equations; the failure patterns obtained by the numerical simulation are found to be similar to those obtained experimentally.

Molecular Analysis of Stable Mutagenesis in Cucumber Induced by High Hydrostatic Pressure

SHI Wei-Guang, WU Hui-Jie, ZHOU Guo-Qiang, JIANG Qi-Feng, CUI Yin-Qiu, LIU Xiao-Yang

2011, 25(4): 379-384 . doi: 10.11858/gywlxb.2011.04.015

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Abstract:
Two mutant cucumber lines are obtained from the Tianjin cucumber cultivar S9925-3 after treatment with high hydrostatic pressure. DNA fingerprint analyses are performed for the two mutants and their parental wild-type cucumber cultivars by AFLP (Amplified Fragments Length Polymorphism) analysis. A total of 30 randomly selected primer pairs are used for AFLP. Ten specific different bands between the mutants and the wild-type cucumber cultivars are excised from the polyacrylamide gel for DNA sequencing. Alignment of the obtained DNA sequences with NCBI (National Center for Biotechnology Information) database identifies the mutation sites in cucumber genome, which may be the reason of phenotypic changes of the mutant cucumbers. This is the first time that a study has showed at molecular level that treatment with high hydrostatic pressure results in stable mutations in cucumber cultivar. Our results indicate that high hydrostatic pressure-induced mutational breeding can be used as an effective approach for the crop improvement.

2011 Vol. 25, No. 4

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