高压物理学报

The Numerical Investigations of Standing Detonation Wave Structure and Performance at the Different Initial Temperatures

DONG Gang, FAN Bao-Chun

2011, 25(3): 193-199 . doi: 10.11858/gywlxb.2011.03.001

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Abstract:
The numerical simulations were performed to study the standing detonation wave structure and performance induced by a supersonic inflow impinging on a cone. The variations of detonation wave structure and the pressure behind the wave at the different initial temperatures of inflow were analyzed. The results show that the ratio of pressure increase is enhanced along with the decrease of the initial inflow temperature, which is benefit from the improvement of propulsion performance of oblique detonation wave engine. At the higher initial inflow temperature, the detonation wave front shows a smooth shape, while at the lower initial temperature, the triple structures appear at the front. The lower initial temperature is, the more number of the serried triple points are. These triple points with higher pressure contribute to the pressure variations behind the standing detonation wave.

Sintering Process of Polycrystalline Diamond Compact under High Pressure

XU Guo-Ping, YIN Zhi-Min, CHEN Qi-Wu, HUANG Ji-Wu

2011, 25(3): 200-206 . doi: 10.11858/gywlxb.2011.03.002

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Abstract:
The polycrystalline diamond compact (PDC) samples sintered at 1 460 ℃, 5.6 GPa and at varied sintering time were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and EDX. In the XRD patterns, graphite (002) peak was found in the sample sintered for 40 s. It was also found that the WC (100) peaks in different samples change from weak to strong and then to weak, and finally disappear with the increase of the sinter time of PDC. Furthermore, the calculated results from the XRD data show that the magnitude of the cell parameter of the cobalt in the diamond layer of PDC increases with the sinter time due to the solution of the W or C. It was observed that the distribution of the cobalt diffusing from the substrate of WC is uneven.

Experimental Investigation on Interface Dynamic Friction of Granite under Combined Pressure and Shear Impact Loading

XU Song-Lin, ZHENG Wen, LIU Yong-Gui, ZHENG Hang

2011, 25(3): 207-212 . doi: 10.11858/gywlxb.2011.03.003

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Abstract:
To investigate the dynamic friction behaviors of rock interface, series of experiments including oblique planar impact with inclination angle 20 and 30, impact loading velocity ranging from 42.2 m/s to 130.6 m/s for Fangshan granite, are carried out. Experiments with inclination angle 20 were carried out to study interfacial properties for specimen without interfacial sliding, and those with inclination angle 30 were used to study the dynamic friction behaviors for specimens with interfacial sliding. Experimental results preliminarily revealed the dynamic friction behaviors of granite surface under the pressures range from 317 MPa to 685 MPa and the surface sliding velocities range from 2.76 m/s to 24.88 m/s. The preliminary results indicated a complicated process of the dynamic friction, which is helpful for the understanding of the earthquake slip.

Confined Pressure Calibration for 3 GPa Molten Salt Medium Triaxial Pressure Vessel under High Pressure and Temperature

HAN Liang, ZHOU Yong-Sheng, HE Chang-Rong, YAO Wen-Ming, LIU Gui, LIU Zhao-Xing, DANG Jia-Xiang

2011, 25(3): 213-220 . doi: 10.11858/gywlxb.2011.03.004

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Abstract:
A triaxial deformation apparatus with 3 GPa molten salt medium pressure vessel was developed. It is based on the conventional Griggs design and the molten salt cell concept modified. There is a huge difference between apparent confined pressure and true confined pressure due to the friction in the assembly and the strength of the confined medium under high temperature and pressure. In this study, we used the partially molten method of LiCl-KCl to make the confined pressure calibration on the basis of the temperature calibration. We successfully observed the simultaneous variation of confined pressure displacement, axial stress and temperature disturbance when the specimen molten initially, then we calculated the true confined pressure by the given equation. Finally, we obtained a series of true confined pressure under different apparent confined pressure of 300~1 400 MPa. Additionally, we gave a interpretation about the friction in the pressure vessel. When the pressure is at 300~500 MPa, the friction percentage changed from 52% to 31.2% gradually. When the pressure is 700~1 200 MPa, the friction percentage dropped about 11.4%. When the pressure is 1 400 MPa, the friction percentage showed a slightly rise from 11.4% to 15.5%. The true confined pressure of the new pressure vessel is not only more accurate than the old one, it has reached the same level with the similar apparatus in other laboratories of the world.

Flatness Study on the Metallic Flyer Driven by Explosive Loading Assembly

ZHANG Zhu, LUAN Guang-Bo, NING Jian-Guo

2011, 25(3): 221-226 . doi: 10.11858/gywlxb.2011.03.005

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Abstract:
The split Hopkinson pressure bar and light gas gun as the two common means of dynamic loading are widely used in dynamic mechanical characteristics of many materials, while it can not meet the experimental study requirements of the concrete and reinforced concrete because of the small loading samples dimensions. To solve this problem, a simple large-dimension explosive loading assembly, which directly drive the flyer devised cone shape to achieve a large-dimension loading, was presented. Numerical simulation was first used to complete the design optimization of experiment conception. The dynamic process which an explosion drove the flyer was simulated based on ALE and Lagrange coupling methods. Then target range experiments were performed and the flyer flatness was measured by using self-made concentric pins, pulse networks and two oscilloscopes. The improvement was proposed prepared for the finally dynamic experiments of the large-dimension concrete and reinforced concrete samples.

Simulation of Ablation Mode Laser Propulsion Efficiency of Confined Target Geometry

TONG Hui-Feng, TANG Zhi-Ping

2011, 25(3): 227-234 . doi: 10.11858/gywlxb.2011.03.006

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Abstract:
Under the irradiation of high power laser, the surface matter of solid target can be vaporized and ionized instantly. The ejected high temperature and high pressure plume generates propulsion force, this is the fundamental of ablated laser propulsion. A general Godunov finite difference WENO (Weighted Essentially Non-Oscillatory) schemes which have fifth-order accuracy is used to conduct a numerical calculation for laser ablated solid target and its ablated propulsion efficiency. Simulation results show that the propulsion efficiency is dependent to varied degrees on the coupling of target cross direction radius with the laser spot size; the confined geometry of the target surface strengthens the propulsion efficiency dramatically.

On the Shape Evolution of Underwater Explosion Bubbles by Cylindrical Charges

HUANG Chao, WANG Bin, LIU Cang-Li, WANG Yan-Ping, TAN Duo-Wang

2011, 25(3): 235-241 . doi: 10.11858/gywlxb.2011.03.007

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Abstract:
Oscillation images of underwater explosion bubbles generated by cylindrical PETN with length to diameter ratio from 3.35 to 6.75 are conducted in a water tank by using high-speed photography technology. Bubble shape evolution is investigated by involving real detonation processes and Rayleigh-Plesset function. Results show that the initial bubble has an asymmetric shape, and the asymmetry is enhanced as the length to diameter ratio increases. The bubble-water interface expansion motion at the side of the charge exhibits an exponential decay, while along the charge axis the decay tends to piecewise linear, both differ from the Rayleigh bubble. These differences are potentially attributed to the asymmetric energy structure of cylindrical charge, which is similar to the usable energy distribution of a cylindrical charge underwater explosion shock wave.

The Study on Black cBN Synthesis with Different Systems

DU Yong-Hui, ZHANG Tie-Chen, ZHANG Wei-Sen

2011, 25(3): 242-246 . doi: 10.11858/gywlxb.2011.03.008

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Abstract:
As well known, cubic boron nitride display more integrated morphology and larger crystal sizes with the color burn. In this paper, black cBN crystals were synthesized in the systems of Mg+hBN, LiH+hBN, Li3N+hBN+B and B+Li3N, respectively. Optical microscope (OM), X-ray diffraction and Raman spectroscopy were used to make a comparison with different black cBN crystals on the aspect of the synthetic condition, crystal morphology, grain size and residual stress. The results showed that the synthesized cBN with the different system exhibited obvious difference. In order to optimize the cBN synthesis, the appropriate system should be chosen according to diverse demands in practical applications.

Electrical Properties of Thermoelectric Material of PbTe1-xSex Prepared by High Pressure Synthesis

SU Tai-Chao, ZHU Hong-Yu, LI Hong-Tao, LI Shang-Sheng, LI Xiao-Lei, MA Hong-An, JIA Xiao-Peng

2011, 25(3): 247-250 . doi: 10.11858/gywlxb.2011.03.009

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Abstract:
The n-type thermoelectric materials of PbTe alloyed with PbSe (PbTe1-xSex) were prepared by high-pressure and high-temperature method. The structure and electrical properties of PbTe1-xSex were studied at room temperature. X-ray diffraction results indicated that the PbTe1-xSex sample exhibited the NaCl crystal structure. As the increasing of Se content x, the lattice parameter, Seebeck coefficient and resistivity for PbTe1-xSex all decrease, and the power factor increases first and then decreases. The maximum power factor of 21.7 W/(cmK2) was obtained at the x=0.1, which is about 20% higher than that of PbTe.

Numerical Investigation of Penetration Performance of Segmented Rods Penetration into Steel Target

DENG Yun-Fei, ZHANG Wei, CAO Zong-Sheng, CHEN Yong

2011, 25(3): 251-260 . doi: 10.11858/gywlxb.2011.03.010

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Abstract:
The penetration performance of blunt segmented rods was studied with numerical simulations by using hydro code ANASYS-AUTODYN systematically, and the dependence of penetration performance on the connect configuration, shape, spacing distance, impact velocity of segmented rods was also investigated. The numerical results indicated that penetration performance of the segmented rods is significantly greater than the parent continuous rods under some conditions. Simulations on the tests from open literature validate the present work, which can be used to guide the optimal design of weaponry segmented-rod projectiles.

Experimental Study on Damage Effect of Simulated Ship Cabin Subjected to Missile Dynamic Explosion

DU Hong-Mian, WANG Yan, ZU Jing, XU Peng, MA You-Chun

2011, 25(3): 261-267 . doi: 10.11858/gywlxb.2011.03.011

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Abstract:
An experiment of missile dynamic explosion carried by rocket sled was performed. The structure size of simulated cabin, layout of testing points and properties of used instruments were introduced. According to broken lines, acquired light, pressure and acceleration signals, three conclusions were made as follows: First, the designed testing method is effective; Second, the transmission of shock wave in cabin is uneven, while the reflection shock wave on the missile moving direction is about 3.5 times of the other side; The shock wave pressure on the cube corner of cabin is higher than normal reflection pressure on the wall; Finally, the impact vibration on the penetrating bulkhead is about 10 000 g, which is much higher than other points; The vibration amplitude of bulkhead will increases as hit by shell fragments.

The Microstructures in 0.20%C Carbon Steel Induced by High-Current Pulsed Electron Beam

LI Yan, CAI Jie, ZOU Yang, WAN Ming-Zhen, GUAN Qing-Feng

2011, 25(3): 268-274 . doi: 10.11858/gywlxb.2011.03.012

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Abstract:
In order to investigate superfast deformation behavior of metal, annealed 0.20%C carbon steel was irradiated with high-current pulsed electron beam (HCPEB). The microstructures of irradiated samples were investigated by using X-ray diffraction (XRD), optical microscopy and transmission electron microscopy (TEM). The experimental results showed that stress of about 1 GPa order was introduced in the irradiated surface layer, which led to severe plastic deformation on the irradiated surface. Both of the complicated configurations of tangle dislocations and dislocation cells were formed within the sublayer. Simultaneously, dislocation loops companied with the dislocations configurations were also produced. In the situation of multi-pulses, characterization by TEM also revealed that the sublayer consisting of some region with the glassy and nanocrystalline structure. It is suggested that the high-level stress and strain rate induced by HCPEB irradiation could cause the shifting of whole atomic planes synchronously. This is the more possible mechanism of the formation of the glassy and nanocrystalline structure.

p-V Equation of State of (Fe0.03Ni0.97)8(Si0.79P0.21)3

YANG Jing, WU Xiang, QIN Shan

2011, 25(3): 275-281 . doi: 10.11858/gywlxb.2011.03.013

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Abstract:
Perryite (Fe0.03Ni0.97)8(Si0.79P0.21)3 sample was synthesized using the standard solid-state reaction. The X-ray diffraction results show that its space group is R3'c with the lattice parameters (a=b=0.663 8(1) nm, c=3.789 2(2) nm, V=1.446 15(6) nm3). In situ high-pressure X-ray diffraction experiments were carried out up to 21.3 GPa at room temperature. No phase transition was observed in the present pressure range. The unit-cell volumes show a smooth decrease with increasing pressure. The variation of the unit-cell volume with pressure was analyzed by Birch-Murnaghan equations of state. Results of the B-M equations of state yield a unit-cell volume (V0) of 1.441 4 (24) nm3 at zero GPa, an isothermal bulk modulus (K0) of 220(7) GPa. Axial compressibility was fitted linearly by Murnaghan equations of state. We obtained Ka=257(9), Kc=165(4). The c axis was more compressible than the a axis.

Study on the Pressure-Volume-Temperature Properties of AO-80/Nitrile Rubber Composites

ZHANG Guo-Rong, ZHAO Xiu-Ying, GAO Yue-Kai, WU Si-Zhu

2011, 25(3): 282-288 . doi: 10.11858/gywlxb.2011.03.014

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Abstract:
AO-80/Nitrile rubber composites were prepared and characterized. According to DMTA experiments, the peak of tan moved towards higher temperature and the peak height of tan was also enhanced while the quantity of AO-80 increased. The pvT data was obtained by pvT dilatometer under different pressures. The parameters of Tait equations were calculated. The results showed that the pvT relationship calculated by Tait equation agreed well with the qualitative observation. The value of parameter b1 decreased while the quantity of AO-80 increased. The specific volume at Tg is smaller when the content of AO-80 was higher. The value of parameter b2 increased while the quantity of AO-80 increased. The expansion of the system with temperature was higher with the increasing of AO-80. The value of parameter b3 and b4 were constants, meaning that the parameter B was constant. The specific volume of the system was mainly affected by the pressure. The average residual of pvT data between theoretical and experimental values were all less than 0.02. It is showed that the Tait equation can be used to describe the pvT relationship of this system.

2011 Vol. 25, No. 3

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