高压物理学报

Surface Stress Characteristics in Pure Nickel after High Current Pulsed Electron Beam Irradiation

QIU Dong Hua, CHENG Du-Qing, GUAN Qing-Feng, ZOU Guang-Tian

2009, 23(5): 321-326 . doi: 10.11858/gywlxb.2009.05.001

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Abstract:
Polycrystalline nickel samples were irradiated with high-current pulsed electron beam (HCPEB). The induced deformation structures were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The relationship between the stress characteristics induced by HCPEB irradiation and the deformation structures was established, and the current numerical simulation results of stress were discussed. The experimental results showed that stress with about 5 GPa had been introduced in the irradiated surface layer, which led to severe plastic deformation (e.g., twin deformation) on the irradiated surface. Both the quasi-static thermal stress and the impact stress wave that induced by plasma pulsed explosion during the HCPEB processing are the main cause of the surface microstructure changes.

Phase Transition of Zn2SnO4 Nanowires under High Pressure

SHEN Xi, SHEN Jun, YOU Shu-Jie, YANG Liu-Xiang, TANG Ling-Yun, LI Yan-Chun, LIU Jing, YANG Hua, ZHOU Wei-Ya, JIN Chang-Qing, et al.

2009, 23(5): 327-331 . doi: 10.11858/gywlxb.2009.05.002

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Abstract:
In situ high-pressure angle dispersive X-ray diffraction (ADXRD) experiments on inverse spinel Zn2SnO4 (ZTO) nanowires were carried out in a diamond anvil cell (DAC) at room temperature. The crystal symmetry becomes lower at around 12.9 GPa and an intermediate phase occurs. At about 32.7 GPa, a phase transition happens and a high-pressure phase appears. After high pressure treatment, the nanowires are broken into nanorods. Through fitting the Birch-Murnaghan equation, we obtained the bulk modulus B0=(168.69.7) GPa for the inverse spinel ZTO nanowires, assuming its first order derivative B0=4 at ambient pressure.

An Experimental Method of Studying Underwater Explosion Bubble Oscillation

WANG Bin, ZHANG Yuan-Ping, WANG Yan-Ping

2009, 23(5): 332-337 . doi: 10.11858/gywlxb.2009.05.003

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Abstract:
Dynamics of bubble oscillation formed during underwater explosions were studied in a 2 m2 m2 m water tank. The theory of shock absorption when elastic wave transmits from high acoustic impedance material to low acoustic impedance material was used. The walls of the water tank were covered with a layer of material having low acoustic impedance. With this set up, the bubble oscillates without influence of the shock waves that reflected from the walls of the water tank. The pressure was measured by piezoelectric pressure transducers, and the explicit pictures of the bubble oscillations and water jet were captured by a digital high speed camera. Another experiment was carried out in an 8 kg test pond to validate the water tank experimental data. The results of the underwater explosion in a water tank are in good agreement with the results getting from the test pond, and the maximal relative deviations between two experimental results is 5.1%. This method is simple and efficient for studying bubble oscillation phenomena.

Wave Velocity and Attenuation Characteristics of Gabbro at 100～300 ℃ and 0.5～4.0 GPa

CHEN Zhi, DU Jian-Guo, ZHOU Wen-Ge, LIU Yong-Gang, LI Ying

2009, 23(5): 338-344 . doi: 10.11858/gywlxb.2009.05.004

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Abstract:
The variations of the elastic properties of gabbro at 100～300 ℃ and 0.5～4.0 GPa and the seismogeological application of the experimental results are discussed based on the measured wave velocities (vP,vS) and quality factors (QP,QS) of the gabbro. The values of vP,vS,QP and QS increase in the pressure range from 0.5 to 4.0 GPa at the given temperatures, but decrease slightly when the temperature increase from 100 to 300 ℃ at the given pressures. The variations of velocities and quality factors may be mainly attributed to the compression of the gabbro sample, and the continuity and elasticity of the sample become better at 0.5～2.3 GPa. The gabbro sample almost becomes continuous elastic medium at 2.3～4.0 GPa, resulting in smaller change of elastic wave velocities and attenuation. The wave velocities and quality factors decrease with increasing temperature because of thermal expansion and density decrease of gabbro. The experimental results can be used to explain the observed geophysical phenomena that the quality factor are enhanced by stress aggregation in the lithosphere, the quality factors may be reduced by rock fracturation and local enrichment of hot fluids in the epicentral areas before and after earthquake occurrence.

Development of a New Fiber Coupled Optical Pyrometer

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

2009, 23(5): 345-352 . doi: 10.11858/gywlxb.2009.05.005

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Abstract:
A fast optical pyrometer for shock temperature measurement was developed based on GDB159/142 photo-multiplier tubes (PMT) and one single optical fiber incorporated with dichroic filters. Main features include the central wavelengths within the spectrum range of 340～811 nm, a rise time of 2～3 ns, and measurable shock temperature span of 2 500～15 000 K. Results of the pulse-linearity measurements indicate that the dynamical linearity values for all six channels are greater than 200 mV (50 load resistor) which meet the requirement for recording on the digital oscilloscopes with good signal-to-noise ratio. Calibration method by the spectral irradiance with a halogen lamp and examples of dynamic measurements are presented. It is demonstrated that this system produces reasonable outputs with stable performance at an economical cost.

Numerical Simulations on Penetration of Rod Projectiles into YB-AD90 Ceramic Targets

SUN Zhan-Feng, XU Hui, LI Ping, HE Hong-Liang, PENG Jian-Xiang, LI Da-Hong

2009, 23(5): 353-359 . doi: 10.11858/gywlxb.2009.05.006

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Abstract:
JH-2 constitutive model parameters of YB-AD90 ceramic were derived from experiments and literatures. The penetration depths and the dynamic penetration processes of rod projectiles into YB-AD90 ceramic targets were numerically simulated using Autodyn-2D. The results indicate that the simulation method and parameters of JH-2 model are acceptable. Some important features in the penetrating processes such as the shape change of the projectile head, the material fragmentation, and the channel collapse are simulated and discussed. The simulation results are consistent with experimental results.

Numerical Simulation on Propagation of Underwater Blast Shock Wave in Absorber Structure

LI Shun-Bo, DONG Zhao-Xing, QI Yan-Jun, SUN Shu,

2009, 23(5): 360-366 . doi: 10.11858/gywlxb.2009.05.007

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Abstract:
The underwater blast shock wave in absorber structure was numerically simulated by ANSYS/LS-DYNA. The results showed that the shock waves decay in the absorption foam layer due to the effect of the constitutive of the foam material, and the peak pressure of the stress wave in the multi-layer structure containing foam concrete has a greater decline than that with foam aluminum, but this has little impact on shock wave transmission. The shock peak pressure in the protective structure with absorbed layer is only 14% of that without an absorbed layer. Further analysis showed that the total energy of foam concrete is higher than that of foam aluminum, indicating foam concrete is superior to foamed aluminum as the absorbed layer in protective structure.

Two-Dimensional Numerical Simulation of Explosion for Premixed CH4-O2-N2 Mixture

LI Cheng-Bing, WU Guo-Dong, JING Fu-Qian

2009, 23(5): 367-376 . doi: 10.11858/gywlxb.2009.05.008

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Abstract:
Based on the reduced methane oxidized element reaction model, CFD software and ISAT algorithm were used to establish a two-dimensional turbulent explosion model for premixed CH4-O2-N2 mixture. Computational results show that the process of ignition, combustion and explosion of the premixed CH4-O2-N2 mixture can be simulated well by the model. The influence of the initial temperature of the high temperature core and the component of mixture on combustion and explosion were considered in the numerical computations. Simulation results indicate that the initial temperature of the high temperature core has an important effect on the ignition delay time and the early combustion phase of the premixed CH4-O2-N2 mixture, but it hardly affects the CJ deflagration phase. The reaction activity of the premixed mixture is reduced by adding N2, which results in the increase of ignition delay time and the decrease of deflagration reaction speed, explosion overpressure and free radical concentration. The computational results of explosion overpressure are in good agreement with experimental results on the same conditions.

Effects of High Hydrostatic Pressure Treatment on Holothurians Autoenzyme Activity

XIA Yuan-Jing, LIU Zhi-Jun, LI Ning, CHEN Shu-Hua, DENG Ji-Song, LIU Xue-Wu, LI Zhi-Yi

2009, 23(5): 377-384 . doi: 10.11858/gywlxb.2009.05.009

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Abstract:
The high hydrostatic pressure treatment on sea cucumber has many advantages over traditional processes and it has a promising future. Effects of processing parameters on holothurians autoenzyme activity were investigated within the range of the parameters: the processing pressure of 0.1~550 MPa, the pressure-keeping time of 0~30 min, the processing temperature of 24~62 ℃. Under the room temperature and pressure-keeping time of 20 min, the autoenzyme activity decreased to 88.25% at 200 MPa, increased to 106.77% at 250 MPa, and reached the lowest level of 29.81% at 550 MPa. The holothurians autoenzyme activity increased first and then decreased with the increasing of pressure-keeping time and temperature. The effect of pressure-keeping mode on holothurians autoenzyme activity was not significant. The BP artificial neural network was used to predict the effects of high pressure on holothurians autoenzyme. Compared with the experimental results, the average relative error of predicted results was 0.9%. The experimental results show that the holothurians autoenzyme can be activated and inactivated at certain pressure, pressure-keeping time and temperature. The study provides some valuable information for optimizing the high hydrostatic pressure treatment of holothurians autoenzyme inactivation.

Research on the Mechanical Performance of PTFE/Al Reactive Materials

XU Song-Lin, YANG Shi-Qing, XU Wen-Tao, ZHANG Wei

2009, 23(5): 384-388 . doi: 10.11858/gywlxb.2009.05.010

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Abstract:
Reactive material is a kind of novel impact initiated energetic material. Understanding the mechanical property of reactive material is an important premise for its application. The tensile and impact properties of polytetrafluorethylene (PTFE)/Al series reactive materials were investigated experimentally using a universal materials testing machine and an improved pendulum impact tester at room temperature. Experimental results show that with the increasing of Al content in PTFE/Al, the tensile strength increases firstly and then decreases. When the Al content is 6%, the tensile strength achieves 36.1 MPa, which is in good agreement with the calculated result. The damage behavior of PTFE/Al is in three steps, including deformation, ductile crack and reaction. With the increasing of Al content, the toughness of PTFE/Al increases firstly, then decreases subsequently. It reaches the maximum of 72.06 /cm2 when Al content is 40%. At the same condition, the difficulty to reaction is also enhanced and the self-sustaining reaction is suppressed.

Research on Hazard of Fragments from Spherical Tank BLEVE

QIAN Xin-Ming, XU Ya-Bo, LIU Zhen-Yi

2009, 23(5): 389-394 . doi: 10.11858/gywlxb.2009.05.011

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Abstract:
Domino effect is a well-known cause of major accidents in the chemical process industries, resulting in overall consequences which are more severe than those of the primary event. Fragment projection is one of the major escalation vectors to cause domino effect. The present work took a spherical tank with boiling liquid expanding vapor explosion (BLEVE) as an example. The probability distribution density of uncertain parameters in the generation and flight of fragments were determined by the data from literatures, and simulated by Monte-Carlo method. Then the projectile distances of fragments were calculated. In this way, the impact probabilities of fragments on objective vessels were attained. The impact probabilities of fragments on the different objective vessels have great gaps. However, the impact probabilities of fragments produced by vessels with different filling levels on the same object are almost same. This method is of great significance for the risk assessment and control of fragments from explosion of spherical tank. It can be used to provide guidance and reference for determining safety distance to prevent domino effect of fragments between storage tanks.

An Optoelectronic Device for mm-Size Projectile Velocity Measurement

ZHAO Jun-Wei, HU Zhi-Yun, ZHAO Xin-Yan, ZHANG Xiang-Rong, QIANG Xi-Wen, ZHANG Tian-Qing

2009, 23(5): 395-400 . doi: 10.11858/gywlxb.2009.05.012

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Abstract:
A novel laser screen detection system was developed to measure the projectile's flight velocity in two-stage light gas-gun. By means of complex anti-jamming methods such as slit aperture limiting external stray light, narrow band spectrum filtering and low frequency notch filtering, the problem of detecting and catching the instantaneous weak disturbance signals from a bright background source was solved, and a high signal-noise ratio was achieved. A typical experiment of a spherical metal projectile with a diameter of 4 mm was performed in a two-stage light gas-gun. The results showed that the inconsistency in projectile's speed between this device and the coil for real-time monitoring is less than 2%, implying this device can meet the requirement of mm-size projectile's velocity measurement in two-stage light gas-gun.

2009 Vol. 23, No. 5

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