高压物理学报

Experiment and Numerical Simulation of Cylindrical Explosive Isostatic Pressing

CHEN Lang, LU Jian-Ying, ZHANG Ming, HAN Chao, FENG Chang-Gen

2008, 22(2): 113-117 . doi: 10.11858/gywlxb.2008.02.001

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Abstract:
The experiments of cylindrical explosive isostatic pressing were carried out. The internal temperatures in pressed explosives were measured by thermocouples. A thermal/structural coupled model of the explosive isostatic pressing was set up. The numerical simulations of cylindrical explosive were conducted. The calculated pressures and temperatures in explosives were given. The deformations,pressures and temperatures distribution were analyzed. The calculated results indicated that each surface center of the cylindrical explosive was sunken by isostatic pressing. During the isostatic pressing of cylindrical explosive, the internal temperature of the explosives increases, and the temperature and pressure are not uniform.

Effect of Inertia on the Dynamic Behavior of Cellular Metal

LIU Yao-Dong, YU Ji-Lin, ZHENG Zhi-Jun

2008, 22(2): 118-124 . doi: 10.11858/gywlxb.2008.02.002

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Abstract:
Although the mechanical property of metal foams has been widely studied, there are some conflicting conclusions on the strain-rate effect and the inertia effect of metallic foams. For a deep understanding of the role of inertia in the dynamic response of cellular metals, finite element method is used to study the dynamic compression of 2D Voronoi honeycombs. Three deformation modes are formulated. Numerical experiments are conducted by changing the density of wall material and the impact velocity. Corresponding macroscopically-averaged stress-strain curves measured on the impact surface and support surface and the plateau stress of the specimens are obtained. According to the simulation results, the influence of inertia is analyzed. It is found that the inertia of the honeycomb has no effect on the stress-strain curve as the macroscopic deformation is homogeneous. However, the inertia effect will result in nonuniform deformation as the impact velocity is high, and thus the plateau stress is obviously increased.

Experiment Research on Spallation Strength under Deviatoric Stress

ZHANG Shi-Wen, LIU Cang-Li, LI Qing-Zhong

2008, 22(2): 125-130 . doi: 10.11858/gywlxb.2008.02.003

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Abstract:
Overstress assembly by heating is adopted to achieve pre-compression along the radial direction of disk-shaped LY12 Al samples. Different deviatoric stress can be obtained using the assembly methods. The spallation signals of these pre-compressed samples were measured with VISAR in light-gas gun shock experiments. The obtained data show that the pullback amplitudes of the free surface velocity in the samples varied significantly even under the same impact velocity. The material's spallation strength is decreased with the incremental deviatoric stress. This method can be used to investigate the relation between spherical spallation and uniaxial strain spallation.

Rapid Preparation and Characterization of Carbon/Zirconia Nanometer Composites

WANG Zuo-Shan, LI Feng-Sheng, LIU Yu-Cun, ZHANG Jing-Lin, LIU Jian-Xun

2008, 22(2): 131-136 . doi: 10.11858/gywlxb.2008.02.004

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Abstract:
Nanometer carbon/zirconia compound powder was synthesized via novel shock wave plasma technique. X-ray diffraction and Raman spectrum were respectively used to characterize the crystal phase composition of the compound powder. Transmission Electron Microscope was used to observe the size and appearance of the as-synthesized powder, precursor and the as-synthesized product. The composition of the compound were tested through DTA/TG analysis. The preparation mechanism was also discussed. The results indicated that the carbon/zirconia compound powder of 10 nm in diameter was synthesized via shock wave plasma technique. The components of the compound powder include 63% (mass fraction) graphite and 37% tetragonal zirconia.

Approximately Theoretical Resolution of the Velocity of the Metallic Flyer Plates Driven by Magnetic Field

WANG Gui-Ji, SUN Cheng-Wei, JIANG Ji-Hao, MO Jian-Jun, TAN Fu-Li, ZHANG Ning

2008, 22(2): 137-141 . doi: 10.11858/gywlxb.2008.02.005

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Abstract:
Based on the energy conservation relation and some assumptions, an onedimensional physical model is proposed to predict the velocity of the metallic flyer plates driven by magnetic field. In this model, the dynamic change of the inductance in work space, the ablation energy and the magnetic field energy produced during the process of magnetic driving are considered. Three experimental examples are used to verify the validity of the model. The results show that the model can accurately predict the velocity of the flyer plates under the conditions of no shock formation and no obvious internal energy accumulation in the plates.

Simulation of Energy Coupling of Laser and Ablated Plasma at Target Surface

TONG Hui-Feng, TANG Zhi-Ping

2008, 22(2): 142-148 . doi: 10.11858/gywlxb.2008.02.006

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Abstract:
Under the irradiation of power laser, the material of solid target surface evaporated instantly and then the vapor plasma of target generated, coupling the energy of laser beam with plasma during the laser go through the plasma field to arrive at the target surface were the main physical process of laser interaction with plasma. A general Godunov finite difference schemes-WENO (Weighted Essentially Non-Oscillatory) schemes which have fifth-order accuracy is used to perform a numerical calculation for 2-dimensional axis symmetrical laser-supported plasma flow field under laser ablated solid target. The models for the calculation of ionization degree of plasma and the interaction between laser beam and plasma and the simplified EOS (equation of state) of plasma are considered in the simulation, the energy of laser absorbed in the plasma and the shielding effect of plasma were analyzed. Simulation results showed that the main portion of laser energy was used to drive the plasma flow, the shielding effect played an important role in the coupling of laser and plasma, the variation of the duration time of laser pulse could adjust the shielding effect which influenced the coupling of laser energy and plasma.

Backward Integration Method for Tracing Isentropic Compression Field

WANG Gang-Hua, BAI Jin-Song, SUN Cheng-Wei, MO Jian-Jun, WANG Gui-Ji, ZHAO Jian-Heng, TAN Fu-Li, HU Xi-Jing

2008, 22(2): 149-152 . doi: 10.11858/gywlxb.2008.02.007

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Abstract:
The govering equation of hydrodynamics are discreted over time. Using a VISAR trace as initial conditions, they are numerically integrated backwards in space. A detail analysis shows good precision has gotten. The traced pressure load history at load surface is consistent with Bai's results. The deduced stress-strain behavior of copper agrees well with the isentropic used in Bai's code.

Numerical Simulations of the Perforation of Aluminum Targets Struck by a Deformable Projectile

HE Tao, WEN He-Ming

2008, 22(2): 153-159 . doi: 10.11858/gywlxb.2008.02.008

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Abstract:
Numerical simulations are conducted on the perforation of aluminum targets struck by an ogive-nosed steel projectile using the commercial FEM code ABUQUS/Explicit. It is assumed that the target response can be represented by a velocity dependent forcing function which is derived from spherical cavity expansion (SCE) analysis. Free surface effects are also considered and a modified forcing function is used in numerical simulations. This approximation eliminates the need for discretizing the target as well as the need for a contact algorithm. It is shown that the numerical simulations are in good agreement with the experimental data for 6061-T651 aluminum alloy targets struck by a VAR 4340 steel projectile.

Study on Standard Cylinder Test Technology and Data Processing Method

SUN Zhan-Feng, LI Qing-Zhong, SUN Xue-Lin, WU Jian-Hua, TANG Tie-Gang

2008, 22(2): 160-166 . doi: 10.11858/gywlxb.2008.02.009

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Abstract:
Standard cylinder test technique and data processing method were studied, and new effective techniques of lighting, negative interpretation and data processing for slit scan experiments were established, and the results of displacement, velocity, acceleration and specific kinetic energy of the cylinder wall particle with high precision and abundant information were obtained. VISAR was used to measure the cylinder expansion velocity and displacement simultaneously. The obtained results are consistent with those from slit scan experiments. The testing reliability was further improved.

The Brittle-Plastic Transition in Experimentally Deformated Quartzite

SONG Juan, ZHOU Yong-Sheng, HE Chang-Rong

2008, 22(2): 167-174 . doi: 10.11858/gywlxb.2008.02.010

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Abstract:
Deformation experiments have been conducted to investigate the brittle-plastic transition of quartzite under temperature of 500~1 000 ℃ and confining pressure of 1 251~1 440 MPa. Mechanical behavior and microstructural characteristics indicated that the brittle-plastic transition of quartzite in experimental condition underwent three deformation mechanisms, namely the semibrittle faulting, semibrittle flow and plastic flow. At least two transitions of deformation mechanism were involved with increasing temperature. The first is the transition from semibrittle faulting to semibrittle flow at 700~800 ℃, and the second is the transition from semibrittle flow to plastic flow at 900~950 ℃. In comparison with the similar results reported by Hirth and Tullis (1994), the temperatures of two transitions we determined is higher by 100 ℃ than Hirth and Tullis' results. In addition, coesite was found in the thin section of severely deformed plastic flow samples.

Synthesis of SrAl2O4: Eu2+, Dy3+ Nanometer Phosphors by Detonation and Combustion Method

QU Yan-Dong, LI Xiao-Jie, ZHAO Zheng, OUYANG Xin

2008, 22(2): 175-180 . doi: 10.11858/gywlxb.2008.02.011

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Abstract:
The SrAl2O4: Eu2+, Dy3+ (SED) nanometer phosphors were synthesized at lower temperature by detonation and combustion method, respectively. The effects of synthesis conditions, annealing temperature on the growth behavior, the particle morphologies and optical properties of the as-prepared SED particles were contrasted. It was showed that the mean size of the SED particles prepared by detonation method increased gradually with increasing heat treatment, and that the mean size of the SED particles prepared by combustion method decreased firstly and then increased quickly and had a minimal value at 600 ℃. The mean size of the SED particles prepared by detonation method increased more quickly than that of the SED particles prepared by combustion method at same annealing temperature. Finally, the mechanism for the long afterglow was discussed and some suggestions on how to improve the synthesis methods were also presented.

Investigation of the Pre-fixed Gap in Single-Pulse Loading Technique of Hopkinson Pressure Bars

CHEN Rong, LU Fang-Yun, LIN Yu-Liang, QIN Jin-Gui

2008, 22(2): 187-191 . doi: 10.11858/gywlxb.2008.02.012

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Abstract:
In conventional Split Hopkinson Pressure Bars (SHPB) experiments, the tension pulse reflected from the sample back into the incident bar will travel to the free end of the bar and then will reflect back to the sample as compression wave. As a result, the sample is loaded many times. The single-pulse loading technique of the Hopkinson pressure bars can solve the problem. This paper presents the basic principle of the single-pulse loading technique of Hopkinson pressure bars. The way to calculate the pre-fixed gap between the transfer flange and reaction mass is given. The experimental results with various pre-fixed gap are obtained. A device of the single-pulse loading technique is set up. High speed photography is applied to confirm the validation of the technique. Both the photoes and the experimental strain waves show that sample was loaded only once.

Raman Spectra Characterization of Cycloheptane under High Pressure

GAO Ling-Ling, MA Yan-Mei, LIU Dan, HAO Jian, JIN Yun-Xia, WANG Feng, WANG Qiu-Shi, ZOU Guang-Tian, CUI Qi-Liang

2008, 22(2): 192-196 . doi: 10.11858/gywlxb.2008.02.013

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Abstract:
In situ Raman spectra of cycloheptane have been characterized under high pressure generated by diamond anvil cell (DAC) at room temperature. The pressure is up to 17.00 GPa. With the increase of pressure, the cycloheptane experienced the liquid-solid phase transition at 0.53 GPa. During 3.45~5.58 GPa, both the curve of Raman frequence-pressure and FWHM-pressure presented inflexions, indicating a potential solid-solid phase transition of cycloheptane.

A Vertical Shock Tube for Experimental Studies on Interfacial Instability

ZOU Li-Yong, LIU Jin-Hong, WANG Jian, HUANG Wen-Bin, TAN Duo-Wang, LIU Cang-Li

2008, 22(2): 197-202 . doi: 10.11858/gywlxb.2008.02.014

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Abstract:
A new vertical shock tube was developed in order to investigate different stages of the development of hydrodynamic interfacial instability. The versatile shock tube permits the execution of three kinds of experiments on the turbulent mixing of fluids induced by the (1) Richtmyer-Meshkov instability at the gas-gas interface (initial perturbations are imposed on a thin nitrocellulose membrane), (2) Rayleigh-Taylor instability at the gas-liquid interface (acceleration of the contact boundary of different density fluids g12104 m/s2), and (3) combined Rayleigh-Taylor and Richtmyer-Meshkov instability at the gas-liquid interface (the first shock wave Mach number ranges from 1.05 to 2.5). The main benefits of such a facility are that it allows, first, to perform multiple experiments of interfacial instability and, second, to measure different transition phases from the beginning to the fully developed turbulent mixing stages.

A Combined Measurement with Pyrometer and VISAR

LI Jun, ZHOU Xian-Ming, LI Jia-Bo, WANG Xiang

2008, 22(2): 203-207 . doi: 10.11858/gywlxb.2008.02.015

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Abstract:
Combined measurement with two or three different diagnostic systems in one shock-wave experiment, which could provide more information on high-pressure physical properties of materials and help people better understanding the nature of these properties, is the inexorable trend for the development of the shock-wave experimental technique. A combined diagnostic technique with multi-channel pyrometer and VISAR was primarily developed in two-stage light gas gun experiments. In one experiment, we successfully obtained spectral radiance histories and particle velocity profiles of LiTaO3 sample by this technique, which indicated shock-induced luminescence and shock-induced phase transformation of LiTaO3. The results show that combined measurement with pyrometer and VISAR is practicable for our shock-wave experiment.

Numerical Study on Influencing Factors of Dynamic Response of Cylindrical Shell Subjected to Deep Water Blast Wave

JIA Xian-Zhen, HU Yi-Ting, DONG Ming-Rong, XU Xue-Zhong, LIU Jia-Cong

2008, 22(2): 208-214 . doi: 10.11858/gywlxb.2008.02.016

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Abstract:
Numerical investigation was carried out on a cylindrical shell subjected to deep water blast wave by using ABAQUS software package. The simulation contained static analysis by using ABAQUS/Standard and dynamic analysis by using ABAQUS/Explicit, and the analysis result of the former was imported into the latter as the initial condition, and then the influencing factors of dynamic response of cylindrical shell were identified. The calculated results indicated that the dynamic response of cylindrical shell was influenced by depth, orientation of explosion and prestress. The damage and distortion of cylindrical shell increases with depth, and the velocity-time history of cylindrical shell particle becomes smoother as the depth increases. The dynamic response to different orientations of explosion is distinct. Prestress leads to severe damage and distortion of the cylindrical shell, which also relates to orientation of explosion. Research results are valuable in evaluating the vulnerability of submarines.

Effect of Boron Contained in the Catalyst on Thermal Stability of Boron-Doped Diamond Single Crystals

WANG Mei, LI He-Sheng, LI Mu-Sen, GONG Jian-Hong, TIAN Bin

2008, 22(2): 215-219 . doi: 10.11858/gywlxb.2008.02.017

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Abstract:
The synthesizing diamond experiment was carried out at cubic hinge press apparatus with iron-based catalyst made by powder metallurgy, in which hexahedral nitride boron (h-BN) was doped with different proportions. Microstructures and morphologies of the diamond single crystals were observed under stereological microscope, and the boron concentration was investigated by electron probe microanalysis (EPMA) and wave distribution spectrum (WDS). It is shown that boron element exists on the (111) crystal surface of diamond, and the concentration of boron changes with boron content in the catalyst. Static compressive strength was also measured. Furthermore, impact toughness measurement, different thermal analysis (DTA), and thermal gravity (TG) analysis were performed to probe into the thermal stability of different boron-doped diamond in atmosphere. The results demonstrate that boron content in the catalyst plays a very important role in mechanical performance and thermal stability of boron-doped diamond, which possess optimum values with increase of the boron concentration.

Microwave Radiation Measurement on Hypervelocity Impacts

MA Ping, LIU Sen, HUANG Jie, SHI An-Hua, MIAO Jun-Gang

2008, 22(2): 220-224 . doi: 10.11858/gywlxb.2008.02.018

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Abstract:
The microwave radiation intensity measurement on hypervelocity impacts were conducted with the 8 mm microwave radiometer at the hypervelocity impact facility at HAI, CARDC. The paper presented the test results of the microwave radiation resulted from hypervelocity impacts on the semi-infinite aluminum and semi-infinite copper target materials. The projectiles were LY12 aluminum spheres with impact velocity ranged from 1.98 km/s to 4.3 km/s. The projectiles were 5 mm in diameter. The impact angle is 0. The microwave radiation intensity were measured in the approach of fixing projectiles, varying projectile velocity and target materials. The results showed that the hypervelocity impact induced microwave radiation could be detected obviously under test conditions. The microwave radiation intensity of the semi-infinite copper target materials duo to hypervelocity impacts was higher than that of the semi-infinite aluminum target materials under the same conditions.

On the Characteristics of Cavitation Formation Subjected to Underwater Blast Shock Wave

LI Hai-Tao, ZHU Xi, HUANG Xiao-Ming, MU Jin-Lei

2008, 22(2): 181-186. doi: 10.11858/gywlxb.2008.02.019

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Abstract:
On the basis of plane shock wave hypothesis, the characteristics of local cavitation and bulk cavitation formation subjected to underwater explosion were theoretically and experimentally studied. The effects of structure dimensions and shock wave parameters on the cavitation formation were analyzed theoretically. Aiming at validating the local cavitation theory,an underwater explosion experiment in a 5 m diameter columned water tank was carried out. The explosion layout was as follows: 50 g TNT charge was placed at a 1 m stand-off away from a 1 m square and 2 mm thick steel plate.Results show that different structure dimensions can affect significantly the formation of local cavitation under the same shock wave parameters, and the quantity and depth of charges play an important role in the bulk cavitation formation. The experimental results basically agree with those of theoretical analysis.

2008 Vol. 22, No. 2

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