高压物理学报

An Optimal Design for Planar Two-Stage Strong Detonation Driving Device

WEN Shang-Gang, SUN Cheng-Wei, ZHAO Feng, TAN Duo-Wang

2009, 23(2): 81-86 . doi: 10.11858/gywlxb.2009.02.001

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Abstract:
Based on the improved Gurney model for explosive acceleration, a planar two-stage strong detonation driving device has been optimized with genetic algorithm. The flyer and the explosive are steel and JO-9159, and the thicknesses of the first and the secondary flyer are 2.5 mm and 0.5 mm, respectively. The maximal velocity of the secondary flyer and the optimized thickness of the explosive are obtained at different velocities of the first flyer from 5.0 km/s to 6.5 km/s. In a similar way, the optimized parameters are also obtained when the flyer's material is aluminium, copper, molybdenum and tantalum, respectively, with a initial velocity of the first flyer of 5.0 km/s. The calculation results can be used in experimental design of planar two-stage strong detonation driving device.

High Pressure Synthesis and Electric Transport Properties of La Filled CoSb3 Skutterudite Thermoelectric Materials

JIANG Yi-Ping, JIA Xiao-Peng, MA Hong-An, SU Tai-Chao, DONG Nan, DENG Le

2009, 23(2): 87-90 . doi: 10.11858/gywlxb.2009.02.002

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Abstract:
La-filled skutterudite compounds LaxCo4Sb12 (0＜x1.0) were successfully synthesized at 3.5 GPa and 900 K. The X-ray diffraction results indicate that all synthesized samples exist as a single phase with a crystal structure of CoSb3. The composition-dependent electric transport properties of La-filled CoSb3 have been studied at room temperature. The lattice parameters of the samples increase gradually with the increasing of La content. No La phase is found in the range of x from 0.1 to 1.0. The La-filled skutterudite is p type semiconductor. The electrical resistivity and Seebeck coefficient increase firstly with the increasing of La content and then decrease. When the La content x is 0.3, the electrical resistivity and Seebeck coefficient both reach the maximum value. The maximum power factor is obtained when the La content x is 0.5.

Thermodynamic Characteristics of Machining Insulating Engineering Ceramics with Electrical Discharge Channel

LIU Yong-Hong, YU Li-Li, XU Yu-Long, JI Ren-Jie, LI Qing-Yun

2009, 23(2): 91-97 . doi: 10.11858/gywlxb.2009.02.003

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Abstract:
A new technique of machining insulating engineering ceramics with instantaneous high temperature produced by electrical discharge channel (EDC) flowing insulating engineering ceramic surface is developed. The mathematical models for the temperature and thermal stress of machining insulating ceramics with EDC are established. The numerical simulation on the temperature gradient and thermal stress of electrical discharge machining insulating engineering ceramics are done. The distribution of the temperature gradient and thermal stress produced by EDC on the insulating engineering ceramic surface are given. The simulation results give the theoretic foundation for revealing the micro-scale mechanism of removing insulating engineering ceramics with EDC, predicting the microcosmic profile of insulating engineering ceramic surface machined by EDC, and selecting the electrical parameter for the new process.

Design and Temperature Calibration for Heater Cell of Split-Sphere High Pressure Apparatus Based on the Hinge-Type Cubic-Anvil Press

CHEN Xiao-Fang, HE Duan-Wei, WANG Fu-Long, ZHANG Jian, LI Yong-Jun, FANG Lei-Ming, LEI Li, KOU Zi-Li

2009, 23(2): 98-104 . doi: 10.11858/gywlxb.2009.02.004

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Abstract:
A new type of heater cell for the split-sphere high pressure apparatus based on the hinge-type cubic-anvil press was reported. This heating apparatus has the advantages of being simple, low cost, fast temperature rising, good heat insulation, and the temperature signal can be easily extracted. Carbon tube was used as a heating element for side-heating in our experiments. The size of the sample in the cell can reach 3 mm in diameter, and 7 mm in height. The relationship between the heating electric power and cell temperature was calibrated with Pt6%Rh-Pt30%Rt thermocouples under different pressures. The experimental results indicate that the temperature can reach 1 700 ℃ under the oil hydraulic pressure of 40 MPa (cell pressure is about 10 GPa).The temperature can keep stable for more than 2 h under a fixed power.

Improvement on Experiment Technique of Measuring Shear Viscosity of Aluminum under Shock Compression

LI Yi-Lei, LIU Fu-Sheng, MA Xiao-Juan, LI Yong-Hong, ZHANG Ming-Jian, ZHANG Ji-Chun

2009, 23(2): 105-110 . doi: 10.11858/gywlxb.2009.02.005

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Abstract:
Because there are great systematic deviations in viscosity coefficients at high pressure when measured by different experiment techniques, it is necessary to improve the experiment technique and obtain more reliable experiment data. In this paper, by the method of improvement on flyer-impact technique, the oscillatory damping and reverse-phase oscillation process on sinusoidally small-perturbed shock front of aluminum at 101 GPa is detected. The shear viscosity coefficient is deduced to be about 800 Pas based on Miller and Ahrens' analytic solution for non ideal initial condition.

Numerical Simulation of Dynamic Response of Concrete Subjected to Internal Load of Blast

LENG Bing-Lin, XU Jin-Yu, SUN Hui-Xiang, XU Jie

2009, 23(2): 111-116 . doi: 10.11858/gywlxb.2009.02.006

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Abstract:
It is still difficult to give the all-sided and accurate description of explosion damaging effects according to experiment. In this paper, by using nonlinear dynamic finite-element program ANSYS/LS-DYNA, which can deal with fluid-solid coupling algorithm, dynamic response of concrete subjected to internal blast loading such as development of cavitations was simulated. The size of the blast pit, the damage area, pressure contour and stress-time curve in concrete with or without steel composite were analyzed. Also, the damage mechanism of concrete-steel plate composition under explosive loading was studied. Research showed that the fluid-solid coupling algorithm can avoid element abnormality and mesh vanishing, and also improve the efficient. The calculated results described the concrete breakage of the center blasting cavity compression and the free surface tension spalling, which were in agreement with the theoretical results. Synchronously, due to the steel plain reinforcing, the steel plate composite can decrease the pull stress and restrain the development of crack, thereby the capability of the prevent-collapse and integrality of the structure will be improved.

Loading and Unloading Process, Phase Transition, and Spallation in FeMnNi Alloy under High Shock-Compression

LI Qing-Zhong, CHEN Yong-Tao, TANG Tie-Gang

2009, 23(2): 117-122 . doi: 10.11858/gywlxb.2009.02.007

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Abstract:
Using VISAR interferometer and X-ray, phase transition and spalling behavior of FeMnNi alloy under high pressure were studied by symmetric impact and reverse impact experiments. In the loading process, the FeMnNi alloy experienced a phase transformation, the velocity of the transition was greater than that of the plastic wave, and thus incorporated into a single phase transition wave. In the unloading history, the reverse phase transition also might take place and the rarefaction waves S1 and S2 formed besides the center-rarefaction wave R. The multi-spallation happened for symmetrical and same thickness high pressure in FeMnNi alloy. By analyzing the interaction among the rarefaction waves S1, S2 and the rarefaction R, it was found that the phase transition and reverse transition of the sample are the main causes of multi-spallation.

Temperature Measurement of Laser-Induced Plasma Detonation Wave

LU Jian-Ying, CHEN Lang, WU Jun-Ying, FENG Chang-Gen

2009, 23(2): 123-129 . doi: 10.11858/gywlxb.2009.02.008

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Abstract:
When a highly intensive laser beam is focused into quiescent air, a laser induced plasma detonation wave is generated. The plasma temperature is an important parameter to describe the plasma detonation wave characters. It is significant to obtain the plasma temperature by experimental method for understanding the mechanism of laser supported detonation wave. In this paper, the ignition, growth and propagation of the laser induced plasma detonation waves were theoretically analyzed and a laser supported detonation wave model was given. The main factors of influence on plasma temperature were deduced in this model. We used pyrophotometer to measure the light emission produced by laser induced plasma to determine values of the laser supported detonation wave temperature at atmospheric pressure. The temporal evolution of plasma temperatures under different laser energies was obtained. The results show that three wave peaks appeared in the temperature history curve, the maximum temperature of laser induced plasma detonation wave is about 7 000～10 000 K, and variation in the laser energy has no apparent change in the temperature.

The Dynamic Behavior of CO at 5 000 K and 25 GPa

LI Xiao-Feng, PENG Wei-Min, ZHAO Feng, ZHANG Yan-Li, JI Guang-Fu, CUI Hong-Ling

2009, 23(2): 130-136 . doi: 10.11858/gywlxb.2009.02.009

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Abstract:
The chemical reaction of CO, being one of the main explosive denotation products, was investigated at 5 000 K and 25 GPa by ab initio molecular dynamics simulations. The final products are C3O2, CO2, and C2O2. The infrared spectroscopy of the system is agreement with many theories and experiments. Radial distribution function (RDF) of the system shows the characteristics of high density fluid. Density of states (DOS) of the products was also presented. By analyzing the mechanism of products of CO under the extreme condition of 5 000 K and 25 GPa, we found that the reaction of CO is mainly due to intermolecular collisions, and transition state is not found in the system.

Three-Body Interactions and Shock Compression Properties of Condensed Nitrogen

SUN Yan-Yun, LIU Fu-Sheng, ZHANG Ming-Jian, XU Li-Hua

2009, 23(2): 137-142 . doi: 10.11858/gywlxb.2009.02.010

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Abstract:
Based on ab initio calculation of quantum-chemical theory, the repulsive potential among three nitrogen molecules (N2)3, as well as that between two nitrogens (N2)2, were calculated for a large amount of molecular directions from randomly sampling. The molecular distance and the geometry of the considered (N2)3 count the multi-body correlations in condensed nitrogen, and spherically averaged approximation of the orientation described the effect of high temperature. An analytic formula of the effective pair potential, which includes effects from various 3-body interactions, was proposed. It is found that three-body contribution obviously soften the average pair potential. The newly determined repulsive potential, combined with van der Waals long-range correlation, was used to predict Hugoniot curve of liquid nitrogen by the fluid-perturbation variational statistical theory. The good agreement between theoretical Hugoniot and the available experimental data indicates that the present scheme for the effective pair potential is reliable.

Equation of state of detonation products for PETN explosive

ZHAO Yan-Hong, LIU Hai-Feng, ZHANG Gong-Mu

2009, 23(2): 143-149 . doi: 10.11858/gywlxb.2009.02.011

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Abstract:
The equation of state of detonation gas products is described by Ross's modification of hard-sphere variation theory and the improved one-fluid van der Waals mixture model. The Gibbs free energy of dissociated carbon is calculated for the most probable state, which is determined by distinguishing the following four states of carbon: graphite, diamond, graphitelike and diamondlike. The equilibrium compositions of detonation products are calculated by solving chemical equilibrium equations based on minimizing free energy. The detonation properties at CJ point of PETN explosives are calculated with this theory and the results show satisfactory agreement with the experimental data. We have also compared the adiabatic expansion from the CJ point calculated with the present theory and JWL equation. The adiabatic gamma decreases in the present theory but exhibits double peak in JWL equation. We suggest that double peak in JWL equation is made by the equation form itself and it doesn't correspond with actual physical process.

The Influence of Filter on Channel Linearity of Instantaneous Optical Pyrometer

WANG Rong-Bo, LI Ze-Ren

2009, 23(2): 150-154 . doi: 10.11858/gywlxb.2009.02.012

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Abstract:
Filter is an important subassembly of instantaneous optical pyrometer system, and the parameters of filter have serious influence on performance of optical pyrometer. In this paper, the influence of filter's bandpass half width, background transmittance and peak transmittance on the channel linearity had been discussed. The results of calculation indicate that the filter's parameters have greater influence on channel linearity. The results provide reference for selecting proper filter in design of high-performance optical pyrometer.

Numerical Simulation of Extended Penetrator with Attack Angle Penetration into Spaced Targets

LI Chang-Shun, LIU Tian-Sheng, WANG Feng-Ying, GAO Yong-Hong

2009, 23(2): 155-160 . doi: 10.11858/gywlxb.2009.02.013

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Abstract:
The extended penetrator penetrating single layer and two-layer spaced targets with attack angle were simulated with LS-DYNA3D, which were compared to that of the baseline rod with the same mass and outer radius. The variation of kinetic energy with time were obtained for extended penetrator and baseline rod respectively. It was demonstrated that the attack angle, velocity and target delamination have effects on the ability of extended penetrator penetrating targets. The advantage of extended penetrator is obvious at high velocity or little attack angle. When the space of the targets equals to the length of the baseline rod, the influence of the target delamination on the penetrating power of expended penetrator is weak, but the influence on the baseline rod is strong, which indicates that the ability of the extended penetrator penetrating two-layer spaced targets is stronger than that of baseline rod.

2009 Vol. 23, No. 2

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