高压物理学报

Phonon Spectrum and Elastic Constants of Copper at High Pressure

MA Gui-Cun, LIU Wei-Feng

2008, 22(4): 337-342 . doi: 10.11858/gywlxb.2008.04.001

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Abstract:
Based on the embbeded atom method (EAM) of Foiles, Baskes and Daw, We have established the EAM potential of Copper by using Vinet-Rose universal equation of state. Phonon spectrum and elastic constant of copper at high pressure are calculated by first principle perturbation theory and embedded atom methods. Through properly adjustment of the parameters in EAM potential, we get almostly the same results for the two methods. Furthermore the spectrum of phonons and the specific heat of lattice are all coincide with the experimental values.

Numerical Simulation of Projectile Shape Effects on Craters in Hypervelocity Impact on Thick Alloy Aluminum Target

ZHANG Wei, GUAN Gong-Shun, JIA Bin, PANG Bao-Jun

2008, 22(4): 343-349 . doi: 10.11858/gywlxb.2008.04.002

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Abstract:
The numerical simulation of projectile shape effects on craters in hypervelocity impact on thick alloy aluminum target at normal angles has been carried out using the AUTODYN hydro-codes in this paper. The results of 2D and 3D simulation are given. The effect of projectile aspect ratios with different shapes and impact orientations etc. on damage characteristics sizes and shapes of craters produced by hypervelocity impact on alloy aluminum targets have been investigated with the same mass and velocity. The simulation results are compared with the crater created by spherical projectiles. It is shown that projectile has a larger aspect ratio, it has a larger crater depth; the damage characteristics sizes and shapes of craters created by non-spherical projectiles impact are different with the projectile shapes and impact orientations.

Study on Chemical Reaction Models in Gaseous Detonation Numerical Simulation

WANG Gang, ZHANG De-Liang, LIU Kai-Xin

2008, 22(4): 350-356 . doi: 10.11858/gywlxb.2008.04.003

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Abstract:
Three common chemical reaction models in gaseous detonation numerical simulation have been studied in this work based on an improved space-time conservation element and solution element method. Planar and cellular detonations have been simulated and the numerical results have been compared and discussed. We found that the cellular patterns simulated by the three chemical reaction models all could agree well with the experimental results, though the accuracies of detonation parameters calculated by the three chemical reaction models were different. The three chemical reaction models all have advantage and disadvantage. Adopting which chemical reaction model should consider the specified problems.

Eulerian Grid Subdivision Algorithm Based on Unsplit Method

NING Jian-Guo, LIU Chun, MA Tian-Bao

2008, 22(4): 357-363 . doi: 10.11858/gywlxb.2008.04.004

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Abstract:
When dealing with the problems of multi-material interaction explosion and impact numerical simulation, hydrodynamics numerical methods of Euler is one of the most effective ways. When using unsplit method to deal with pure cells in Euler coordinate, mixed cells are subdivided based on Youngs' interface reconstruction algorithm which can avoid complicated transport calculation. This paper gives all of the possible distribution modes to eight neighboring cells of both pure ones and subdivided ones. In the end, this unsplit method is added into numerical simulation program of MMIC-2D universal multi-material two-dimension explosion and impact which is developed by ourselves. The simulation results verify that our method can not only improve calculation precision efficiently, but also reduce workload and save time.

The Experiment Design for Explosive Welding of Multilayer Amorphous Foils

FU Yan-Shu, SUN Yu-Xin, WANG Xiao-Ping, ZHANG Xiao-Li

2008, 22(4): 364-369 . doi: 10.11858/gywlxb.2008.04.005

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Abstract:
Because of the high strength and temperature sensitivity of the metal glass, its lower limit is higher and upper limit is lower than crystal metal when bulk metal glass was prepared by amorphous foils explosive welding. In this paper, the surface of foils was coated by copper to decrease surface hardness. Results showed that this method can reduce the lower limit, concentrate the energy of plastic collision mainly on coating layer and remarkably minimize foils heat effect zone. Besides, during the experiment designing, ideas of damage mechanics were used to set defects to accelerate the attenuation of tensile waves, so the tensile strength which arrived at welding interfaces can be reduced,combined with the model of thermosoftening at welding interfaces, it can be concluded that the upper limit was increased. Both of upper limit and lower limit were improved, it can be sure that the welding window was effectively expended, so the purpose of preparing bulk metal glass by explosive welding amorphous foils would be easier to implement.

Construction and Analysis of SSH-cDNA Library Induced by High Pressure in Rice Seeds during Germination

LIU Xun-Cheng, ZHANG Mei, DUAN Jun

2008, 22(4): 370-376 . doi: 10.11858/gywlxb.2008.04.006

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Abstract:
In order to study the effect of expression pattern of high hydrostatic pressure on high plant, a SSH-cDNA library was constructed with rice germinating seeds in this paper. Suppression subtractive hybridization (SSH) in combination with mirror orientation selection (MOS) was performed using the mRNA from rice germinating seeds treated by 75 MPa high hydrostatic pressure as tester and the mRNA from control (seeds untreated by high hydrostatic pressure) as the driver. 580 recombinant clones were picked through blue/white screening. PCR detection of the recombinant clones showed that the size of inserts mainly ranged from 200 bp to 1000 bp, and the average size of these inserts were about 575 bp. Among the 580 recombinant clones, 542 clones (93.3%) were identified to be effective single band ones. After sequencing some of the recombinant clones, it was found that the genes induced by high hydrostatic pressure were mainly involved in metabolism, stress response and transcriptional regulation. The research paved the way for studying the gene expression patterns of rice seeds responding to high hydrostatic pressure.

Numerical Analysis of the Characteristics of Debris Clouds Produced by Hypervelocity Impacts Using SPH Method

XU Jin-Zhong, TANG Wen- Hui, XU Zhi-Hong

2008, 22(4): 377-383 . doi: 10.11858/gywlxb.2008.04.007

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Abstract:
The characteristics of debris clouds produced by hypervelocity impacts are simulated and analyzed by smoothed particle hydrodynamics (SPH). The variational laws of the diameter of holes, the debris clouds width, the cumulative percentage of fragments, the dimensionless momentum MD/M0 and the residual velocity are given. By fitting computational data, the cumulative percentage of fragments as a function of the fragment mass and the impact velocity is presented. The computational results show that the function agrees with SPH results very well.

The measurement of Velocity-per-Fringe Constants of VISAR

MA Yun, ZHANG Lin, PENG Qi-Xian, WANG Xiang, LI Jian-Feng, CAI Ling-Cang, LI Jia-Bo, WANG Xiao-Song, WENG Ji-Dong, CHEN Hong

2008, 22(4): 384-388 . doi: 10.11858/gywlxb.2008.04.008

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Abstract:
Four experimental approaches had been developed to measure the velocity-per-fringe constants of VISAR. In particular, owing to the high accuratity and the wide applicable range, the integrated VISAR and DISAR approach should be a versatile method to measure arbitrary velocity-per-fringe constants of VISAR. In the absence of the integrated VISAR and DISAR system, the velocity-per-fringe constants of VISAR can also be measured through the measurement of the VISAR's delay time, the relatively standard velocity source produced by the fused silica symmetric impacting with a window, or the calibrated VISAR.

Optimization of High Pressure Sintering Process for PDC by Orthogonal Experiments

LIN Feng, JIANG Wei, FENG Ji-Fu, LI Li-Wei, Lü Hai-Bo

2008, 22(4): 389-396 . doi: 10.11858/gywlxb.2008.04.009

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Abstract:
The wear ratio, resistance, integrality and hardness of polycrystalline diamond compacts (PDC) are investigated. The high pressure sintering processes are optimized using orthogonal experiments. According to our experimental results, the optimized parameters for the high pressure sintering of PDC are determined as below: pressure 5.5 GPa, temperature 1 350 ℃, temperature rising rate 200 ℃ /min, cooling time 14 min, and sintering time 16 min. It is found that the wear ratio and micro-hardness can be improved by increasing sintering temperature. The temperature distribution in the sample cell is reduced and PDC microstructure becomes more uniform by prolonging the heating time. The residual stress is also found to be decreased by prolonging the cooling time.

Property Comparison of Porous Graphite Nanopowders Prepared by Detonation Splitting Technique with Different Acid Content

SUN Gui-Lei, LI Xiao-Jie, YAN Hong-Hao, WANG Xiao-Hong, JIANG De-An

2008, 22(4): 397-401 . doi: 10.11858/gywlxb.2008.04.010

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Abstract:
N2 adsorption/desorption isotherms and pore diameter distribution of the porous graphite nanopowders, prepared by detonation splitting technique with different acid content in raw materials, were analyzed using Brunauer-Emmet-Teller (BET) equation and Barrett-Joyner-Halenda (BJH) method. The results indicate that there exists hysteresis phenomenon in the product isotherms and the corresponding BET surface area is 5.3~9.2 times of the natural flake graphite which is increasing along with the acid content in raw materials. The difference of the BET surface area among the detonation soot is mainly caused by the pore of which diameter distributing between 3 nm and 7 nm. Moreover, the amount of the pore size at about 4 nm arrived to the maximum after detonation. In addition, the research provides sorption capacity information for application and at the same time it also proves that acid has perfect impact on preparing graphite nanopowders.

Study on the Intensity of the Cylindrical Vessel by the Inner Underwater Explosion Shock Wave

FAN Zi-Jian, SHEN Zhao-Wu, LIAO Xue-Yan, LIU Yuan-Dong

2008, 22(4): 402-408 . doi: 10.11858/gywlxb.2008.04.011

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Abstract:
The paper have analyzed and evaluated the elastic shell strain of the cylindrical vessel by the inner underwater explosion shock wave, according to the thin shell and underwater explosion theory. The numerical results of the relationship between the elastic shell strain and three main factors, i.e. the vessel diameter, the shell thickness and the mass of the inner explosion, is computed, and is evaluated by detailed experiments. The experiment results show better consistency with the numerical results.

Simplification of M-G Model and Experimental Result Analysis of Preheated Mo

WANG Qing-Song, LAN Qiang, WU Jing

2008, 22(4): 409-413 . doi: 10.11858/gywlxb.2008.04.012

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Abstract:
The expressions of Hugoniot parameters of preheated metal were obtained by simplification of M-G EQS model, which made it more easily to determine Hugoniot parameters of metal at various initial temperature using M-G model. The EQS of Mo at 1 400 ℃ had been studied by Miller and Duffy, which was not agree with M-G EQS model. Some problem need to research further.

Temperature Measurement for the Interface of the Dense Bulk Iron/Sapphire Window under Shock Compression

GUO Jin-Liang, LIU Fu-Sheng, HAO Gao-Yu, ZHANG Ming-Jian, ZHANG Dai-Yu, XUE Xue-Dong

2008, 22(4): 414-418 . doi: 10.11858/gywlxb.2008.04.013

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Abstract:
The iron sample is symmetrically impacted by a high speed flyer of the same material, which is launched by use of two-stage light-gas gun. The temperature of the interface between iron and sapphire is determined by measuring the spectra illuminaton. In experiment, a new technique is applied to prepare the bulk iron/sapphire interface, and an improved in-situ method is used to calibrate the pyrometer. As a result, the peak radiation from the directly contacted interface is effectively diminished, and the stable emission from the ideally intacted interface of Fe/Al2O3 is observed. The result shows that the Fe/Al2O3 interface temperature corresponding to the shock pressure of 164 GPa is (3 950180) K.

Multi-Shock Hugoniot Equation of State of Liquid Carbon Monoxide Measured By an Optical Analysis Technique

ZHENG Xue-Ping, LIU Fu-Sheng, ZHANG Ming-Jian, CHEN Xian-Meng, SUN Yue

2008, 22(4): 419-424 . doi: 10.11858/gywlxb.2008.04.014

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Abstract:
The cryogenic target technique and an optical analysis technique are combined to measure multi-shock Hugoniot equations of state of liquid carbon monoxide. The first, second, and third shock pressures are respectively 19 GPa, 60 GPa, and 71 GPa. The maximum compression ratio of volume reaches three point five and twenty percent higher than that of ever reported one. The measured results for specific volume are nearly twenty percent less than the predicted ones by molecular fluid theory, which is attributed to the molecular dissociation reactions of carbon monoxide under shock compressions. The detail of the measurement technique and calculation method are described, and such a scheme can be applied to other molecular fluids to achieve higher pressures and larger compression ratios.

Analyzing Material Strength in Shock-Induced Melting Region with Renormalization Group Theory

RAN Xian-Wen, TANG Wen-Hui, TAN Hua, XU Zhi-Hong

2008, 22(4): 425-428 . doi: 10.11858/gywlxb.2008.04.015

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Abstract:
The material strength in shock-induced melting region was analyzed with renormalization group theory, it indicates that the material strength begin to decrease as soon as the melting mass fraction reach 0.300 798, corresponding to the point at which the longitudinal sound velocity initially turn to bulk sound velocity.

The Research on Dissolvability and Phase Transition of Gypsum at High Pressure and Ambient Temperature

WANG Shi-Xia, ZHENG Hai-Fei

2008, 22(4): 429-433 . doi: 10.11858/gywlxb.2008.04.016

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Abstract:
The Raman spectra of gypsum during the pressure of 200~1 100 MPa is studied at ambient temperature, and the dissolvability and phase transition of gypsum are observed. It shows that gypsum is stable at the pressure less than 407 MPa; and then gypsum begins to dissolve with the increasing pressure. Gypsum stops dissolving and phase transition happens (gypsum-bassanite) to some degree. After phase transition, bassanite disappears with the rising pressure. It applies that geological disasters will happen because of dissolvability and phase transition of minerals in the inner of earth.

Microstructural Characteristics in Al-Based Alloys Solidified under High Pressure

SUN Shu-Hua, LI Jie, ZHAO Hai-Li, XU Rui, LIU Ri-Ping

2008, 22(4): 434-438 . doi: 10.11858/gywlxb.2008.04.017

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Abstract:
The microstructures of hypoeutectic and hyper-eutectic Al-Cu and Al-Si alloys solidified at high pressure (5 GPa) have been investigated. The results showed that high pressure has an evident influence on the morphologies and the dimensions of the solidified microstructures. This influence is directly related to the temperature interval of the liquid-solid region in the phase diagram. When the temperature interval is increased by pressure, the solidified microstructure will be coarsened. When the temperature interval is decreased by pressure, the solidified microstructure will be refined. Moreover, a new method is proposed in this paper to easily evaluate the sizes of the cellular and the dendritic microstructures.

Effects of Dynamic Instantaneous High Pressure Treatment on the enzymolysis rate of Dietary Fiber

WAN Jie, LIU Cheng-Mei, LAN Hai-Jun, TU Zong-Cai, LIU Wei

2008, 22(4): 439-444 . doi: 10.11858/gywlxb.2008.04.018

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Abstract:
The enzymolysis rates of cellulase on dietary fiber under dynamic Instantaneous High Pressure (IHP) were studied in the paper. Utilizing the Microfluidizer machinery as the carrier of Instantaneous High Pressure treatment to deal with dietary fiber from bean dregs, we got dietary fiber of different granularities and densities under different pressures and different times with the same pressure. The corresponding enzymolysis rates of cellulase on dietary fiber were different. The hydrolysates of cellulase on dietary fiber were some reducing sugars, such as cellobiose and glucose. The enzymolysis rates could be judged by measuring the contents of the reducing sugars in the dietary fiber of different granularities and densities. The results indicated that with the increase of the pressure in the range of 40～90 MPa, the granularities of the materials reduced greatly, the densities of the materials and the enzymolysis rates increased. And the granularity of the materials was in minimum at 202.4 nm; when the pressure went on increasing, the granularities of the materials tended to increase because of the occurrence of expanding in the system, but the densities started to decreased and the enzymolysis rates kept increasing. The density of the materials was in minimum at 1.027 g/mL, the contents of the reducing sugars after enzyme hydrolysis was maximal at this time. When the pressure higher than 140 MPa, the granularities and density of the materials increased, the enzymolysis rates decreased. It could be due to the reuniting of particles in the system. When the materials were treated separately with instantaneous high pressure between 90 MPa and 140 MPa for several times, the granularities of the materials increased as the increase of dealing times, the density decreased at the start and then increased, and the enzymolysis rates decreased.

Initial Porosity Effect on the Shaped Charge Jet Behavior

LI Ru-Jiang, SHEN Zhao-Wu, WANG Feng-Ying

2008, 22(4): 445-448 . doi: 10.11858/gywlxb.2008.04.019

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Abstract:
Shock heating can cause temperature rise before the porous liner collapse process because of its porous nature, which is possible to increase the jet temperature and enhance the jet ductility. The temperature rise calculation method was presented, and the porous effect on the jet behavior was studied with the pulse X-ray photograph. It was shown that the jet ductility increase with the initial porosity within some value, and the jet diameter become small.

2008 Vol. 22, No. 4

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