高压物理学报

Study on Photoluminescence of Mn2+ in Zn0.83Mn0.17Se and ZnSe/Zn0.84Mn0.16Se Superlattics under Pressures

WANG Wen-Jie, DENG Jia-Jun, Ding Kun

2011, 25(5): 385-389 . doi: 10.11858/gywlxb.2011.05.001

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Abstract:
The photoluminescence of Mn2+ in Zn0.83Mn0.17Se and ZnSe/Zn0.84Mn0.16Se superlattics was investigated at different pressures. The 4T16A1 transition of Mn2+, which shows different pressure dependence in bulk materials and superlattics, was observed. The pressure coefficients obtained from them are -42.4 and -29.5 peV/Pa, respectively. The theoretical calculation for pressure coefficient of the emissions in Zn0.83Mn0.17Se gave the result -38.3 peV/Pa, which is almost consistent with experiment. Further analysis of pressure dependence for emission intensity confirms that the emission characteristic of Mn2+ was mainly affected by near crystal field. Their different properties mainly root in different band structures and strains in ZnSe/Zn0.84Mn0.16Se superlattics.

Numerical Simulation of the Gas Gun Experiment with Pillow Impactor Loading

BAI Jing-Song, LUO Guo-Qiang, HUANG Jiao-Feng, LI Ping

2011, 25(5): 390-394 . doi: 10.11858/gywlxb.2011.05.002

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Abstract:
The present study is for verification and validation (VV)of the onedimensional elastic-plastic hydrodynamic code MLEP (Multi-material Lagrangian Elastic-Plastic) and method of the mixing model of different material system. Two gas gun experiments with pillow impactor loading were calculated by MLEP, in which one is from the Lawrence Livermore National Laboratory (LLNL) of 19 layers model and the other is from the National Key Laboratory for Shock Wave and Detonation Physics Research (LSD), Institute of Fluid Physics CAEP of 29 layers model. Our simulation results are excellently consistent with the experiments. The work that we have carried out in this paper will become a part of VV and of the further research of controllable loading experiment.

A Numerical Simulation of H2-O2-N2 Gaseous Detonation Based on Detailed Chemical Reaction Model

NING Jian-Guo, LI Jian, WANG Cheng, ZHAO Hui

2011, 25(5): 395-400 . doi: 10.11858/gywlxb.2011.05.003

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Abstract:
Numerical simulation has been performed to study the cellular detonation wave in a mixture using a detailed chemical reaction model with 12 species and 23 elementary reactions and a fifth-order weighted essentially non-oscillatory (WENO) scheme with a third-order TVD Runge-Kutta time stepping method. We study one-dimensional ZND detonation, the detailed structure of self-sustained detonation and flow structure around a triple point. The simulation results suggest that two-dimensional detonation wave front formations are greatly enhanced by the presence of transverse waves. The motion of transverse waves generates triple points, which cause the detonation propagation to become self-sustained.

Experimental Study on Ballistic Resistance Property of 7A04 Aluminum Alloy Against Rod Projectiles Impact

ZHANG Wei, WEI Gang, XIAO Xin-Ke, MU Zhong-Cheng

2011, 25(5): 401-406 . doi: 10.11858/gywlxb.2011.05.004

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Abstract:
7A04 aluminum alloy with high strength-to-density ratio has been extensively applied for armour material domain. The projectiles normal impacting 7A04 aluminum alloy plates with 10 mm thickness was conduct by light gas gun, where blunt and ogival steel rod projectiles were involved. The damage modes and penetration characteristics of the 7A04 aluminum alloy targets were obtained. The whole impact process and the residual velocity were obtained by the high-speed camera system. The comparison of the initial velocity versus residual velocity between blunt-projectile penetration events and ogival-projectile penetration events indicated that 7A04 aluminum alloy plates own stronger resistance ability to ogival projectile impact than that of blunt projectile.

Dynamic Compression Properties and Constitutive Model with Strain Rate Effect of Rubber Material

PANG Bao-Jun, YANG Zhen-Qi, WANG Li-Wen, CHI Run-Qiang

2011, 25(5): 407-415 . doi: 10.11858/gywlxb.2011.05.005

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Abstract:
This paper presents experimental study on the quasi-static and dynamic impact response for three kinds of rubbers: carbon black rubber, silicone rubber and foam rubber by using Instron machine and SHPB device. Experimental strain rate covers a wide range from 0.002 s-1 to 15 000 s-1. The strain rate effects on mechanical properties of rubber materials are discussed. The results show that the quasi-static and dynamic engineering strain-stress curves exhibite different strain hardening forms. Under dynamic loading, the significant rate sensitivities are observed i.e. with strain rate increasing the hardening effect is enhanced. With quasi-static and high strain rate (12 000－15 000 s-1) loading, the mechanical properties of foam rubbers show typical three stages: elastic deformation, plastic deformation and collapse portion. A constitutive model with strain rate effect is presented based on Rivilin strain energy function, which shows good agreement with experimental data.

High Pressure Sound Velocity Measurement of Material in DAC Using Laser Ultrasonics Technique

MA Yun, ZHANG Yi, LI Jia-Bo, CAI Ling-Cang, LI Jian-Feng, LIU Lei, JING Qiu-Min, WANG Zhi-Gang, WANG Xiang, WENG Ji-Dong, et al.

2011, 25(5): 416-420 . doi: 10.11858/gywlxb.2011.05.006

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Abstract:
A prototype laser-based ultrasound system is designed and built to measure the sound velocity of samples at high pressure in a diamond anvil cell. The system uses a Q-switch laser with 6.3 ns pulse width for excitation of broadband ultrasonic waves, and an optical fiber displacement and velocity mixing interferometer for detection. Both longitudinal acoustic wave velocity and in-situ thickness of copper at the pressure of 2.6 GPa are obtained by this all-optical pump-probe technique, which does not require any information beyond that contained in the signal itself.

A Combined Technique for Measuring Hugoniot and Interfacial Temperature of Preheating Metals

LI Jun, LI Jia-Bo, ZHOU Xian-Ming, WANG Qing-Song, DAI Cheng-Da

2011, 25(5): 421-428 . doi: 10.11858/gywlxb.2011.05.007

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Abstract:
Research of dynamic respond properties for metal at initial high-temperature condition is very important to develop the universal equation of state. Thus, resistance-wire preheating apparatus over initial temperature range of 300－800 K has been built up by our group in light-gas-gun experiments, and a non-contact pyrometer diagnostic technique was developed to perform simultaneous measurements of the shock-Hugoniot and the interfacial temperature on a preheated metal. Examples for measuring dynamic respond properties of tantalum are presented. The measured data for shock velocity versus particle velocity at initial temperature of 300 K is in agreement with previous shock compression data, while the data of 773 K lies below the theoretical Hugoniot that was calculated based on the principal Hugoniot. The obtained interfacial temperatures are in agreement with the melting points that shocked from the ambient conditions and ab initio results. It indicates that our target-preheating apparatus and non-contact pyrometer diagnostic technique is a viable approach to study the temperature effects on shock response of metals.

Numerical Simulation of Unsteady-State Underexpanded Jet Using Positive Schemes

ZHU Sun-Ke, CHEN Er-Yun, MA Da-Wei, LE Gui-Gao

2011, 25(5): 429-434 . doi: 10.11858/gywlxb.2011.05.008

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Abstract:
A numerical simulation of unsteady-state underexpanded jet was carried out using second order positive schemes, which was developed to solve the axisymmetric Euler equations based on two dimensional conservation laws. Computational results indicate that the method can capture the wave structures of jet flowfields including expansion fan, incident shock, reflected shock, Mach disk, jet boundary and the triple point well. Agreements between the numerical results and experimental or existed numerical results are fairly satisfactory. It indicates that the present method has high capability in capturing shocks without numerical oscillation near discontinuous points.

Dynamic Behavior of Titanium Matrix Composites under Hypervelocity Impact

SONG Wei-Dong, LI Jian-Qiao, LIU Hai-Yan

2011, 25(5): 435-443 . doi: 10.11858/gywlxb.2011.05.009

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Abstract:
Based on experimental results, numerical simulations were performed to study the hypervelocity impact of aluminum balls against aluminum targets, verifying the reliability of the numerical model. Hypervelocity impact simulations under three different velocities of 5.52, 7.00 and 8.00 km/s against aluminum target and titanium matrix composite target with the same mass of the aluminum target were simulated. The process of aluminum balls with a diameter of 5.02 mm and titanium matrix composite balls with the same mass of the aluminum balls impacting aluminum shields and titanium matrix composite shields were analyzed by using a dynamic analysis program under the above three velocities, respectively. It can be found that the protective effect of the titanium matrix composite shields is more efficient than that of the aluminum shields when increasing the impact velocities. When the velocity is constant, the protective effect of titanium matrix composite shield against titanium matrix composite ball is good and the protective effect of aluminum shield against aluminum ball is good. With a theoretical analysis on impact process, it can be concluded that protective effect of the titanium matrix composite shields is more efficient than that of the aluminum shields.

Dynamic Mechanical Behaviors of Soil under Impact Loads

ZHU Zhi-Wu, NING Jian-Guo, LIU Xu

2011, 25(5): 444-450 . doi: 10.11858/gywlxb.2011.05.010

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Abstract:
The test of the impact characteristic of soil is made on split Hopkinson pressure bar at various strain-rates. The dynamic mechanics properties and the strain-rate effect of soil are discussed. Based on the characteristics of measured dynamic stress-strain curves, as well as preparatory simulation, a new viscoelastic damage model has been introduced. A linear spring is put to parallel to two Maxwell units with different relaxing time to express distinct plastic flow. In the constitutive model, one Maxwell unit with low relaxing time is used to describe the low strain-rate response of soil; and the other one with high relaxing time is used to describe the high strain-rate response of soil.Simulated stress-strain curves using the model is of good consistency with measured curves, and the simulated parameters indicate that the response of the low strain-rate of soil is just the same as that of concrete. Howevwe, the response of the high strain-rate of soil is much more violent than that of concrete.

Numerical Study on the Acceleration of Metallic Flyers Driven by Planar Detonation Wave of Explosives

LUAN Guang-Bo, HAO Li, ZHANG Zhu, 

2011, 25(5): 451-456 . doi: 10.11858/gywlxb.2011.05.011

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Abstract:
As regards the experimental study on the dynamic properties of materials, planar detonation wave driving flyers to impact target is an important technique. The smoothness and limit speed of flyers under detonation load determine the loading effects. The former determines the target size, and the later determines the pressure to the target. Consequently, based on the coupling ALE and Lagrange method, the simulation for the process of detonation wave driving the flyer is performed, and the smoothness of the flyer is given when it approaches the limit speed. The limit speeds of the flyer from numerical results and analytical solution are comparatively analyzed. Finally, we summariz the numerical results and point out the practicality and effectiveness of the fluid-structure coupling method in studying the motive process of flyers under detonation load.

Relationship between Shock Wave and High-Temperature Flow Produced by Gas Explosion in Coal Mine Roadways

PANG Lei, ZHANG Qi, LI Wei, XIANG Cong, TAN Ru-Mei

2011, 25(5): 457-462 . doi: 10.11858/gywlxb.2011.05.012

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Abstract:
In order to provide theoretical basis for in-depth studies of coal dust explosion after gas explosion in coal mines, the unsteady flow field of gas explosion in roadways was numerically simulated by computational fluid dynamics method. The spatiotemporal relationship between shock wave and high-temperature flow was acquired, and the numerical method was verified by virtue of experiment. The study indicated that the near field and part of the far field are prone to secondary explosion of coal dust in certain period after the gas explosion. The functional relation of region of the possible secondary explosion with methane-air mixture length, and the distribution characteristic of arrival time interval of peak temperature and peak overpressure in far field with axial distance and methane-air mixture length were also proposed.

Investigation of Explosive Effect to Followed Projectiles by Shaped Charge of Tandem Warhead

KANG Yan-Long, JIANG Jian-Wei, WANG Shu-You, MEN Jian-Bing

2011, 25(5): 463-468 . doi: 10.11858/gywlxb.2011.05.013

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Abstract:
The explosion of shaped charge of tandem warhead and the impact process on followed projectile of impulse are simulated with a numerical hydrocode of AUTODYN. The maximum acceleration response and kinetic energy attenuation of followed projectile during impact process are analyzed under different projectile mass and diameter. The result indicates that the projectile's maximum acceleration decreased, remainder kinetic energy increased with followed projectile mass increased. An equation of followed projectile's residual velocity with projectile mass is concluded based on simulation results, and it is validated by experimental results.

Numerical Study of Explosives Initiation by Simultaneous Impact from Two Fragments

JIA Xian-Zhen, CHEN Song, YANG Jian, WANG Jian-Ling

2011, 25(5): 469-474 . doi: 10.11858/gywlxb.2011.05.014

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Abstract:
The explosives initiation by simultaneous impact from two fragments was simulated based on Lee-Tarver ignition and growth model by using finite element code LS-DYNA. In order to verify the simulation method and parameters, the courses that tungsten spheres with different diameters impacted tantalum covered Composition B charges were simulated, and the critical velocity to ignite Composition B was gained, which accorded well with the experimental results. The problems that two tungsten spheres with three kinds of diameters impacted Composition B charges were simulated. It can be found that the critical velocity to ignite explosives by two fragments, which was lower than one tungsten sphere condition, varied with the distance between the two fragments approximately in term of parabolic curve. When the impact velocity was equal to or slightly larger than the critical velocity, there can be different shapes of detonation wave appearing in the charge, including spherical, W-shape, V-shape, VW-shape and so on.

Effects of High Pressure Processing on the Activity and the Conformation of Horseradish Peroxidase

SHANGGUAN Li-Juan, MA Yong-Kun, CUI Feng-Jie, FAN Xiao-Bo

2011, 25(5): 475-480 . doi: 10.11858/gywlxb.2011.05.015

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Abstract:
High pressure treatment on the activity of peroxidase in fruits and vegetables can affect the sensory quality and shelf life of fruit and vegetable products, and thus it is necessary to study the relationship between the changes of peroxidase activity and its structure under the conditions of high pressure. Circular dichroism (CD) and fluorescence spectrometry (FP) were used to study the effect of high pressure treatment at 100, 300, 500 MPa for 15 min at room temperature on the secondary and tertiary structure of horseradish peroxidase (HRP) and its activity. The results showed that HRP was pressure-resistant and HRP activities were decreased respectively by 2.36%, 5.69% and 10.36% with the increase of the above pressure. The contents of -helix, -sheet and random coils in HRP were all increased by less than 4%, while the content of -turn was significantly decreased by over 11%. After HRP was processed by high pressure, the HRP fluorescence intensities at the excitation spectra peak of 234 nm and emission spectra peak of 308 nm were decreased respectively by 18.28%, 5.46% and 4.04%. The fluorescence intensity of HRP treated at 100 MPa, 15 min was decreased to the largest extent. The results showed that high pressure processing obviously inactivated the activity of horseradish peroxidase that was related to its structural changes.

2011 Vol. 25, No. 5

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