高压物理学报

High Pressure Dissociation of Typical Diatomic Molecular Solids and Their Atomic Phases

LI Quan, MA Yan-Ming

2013, 27(3): 313-324. doi: 10.11858/gywlxb.2013.03.001

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Abstract:
High pressure can effectively modify the inter-atomic interaction of materials (i.e., the electron orbital overlap, chemical bonding, and electron charge distribution of materials), and further the crystal structures, mechanical, thermal, optical and electrical properties of materials. For more than one century, the progress in experimental generation of highest pressure and the development of advanced theoretical method have significantly moved forward the high pressure science. One of the most challenging research topics under high pressure is targeted to the investigation of pressure induced diatomic molecular dissociation. This article reviewed the high pressure dissociation of typical diatomic molecular solids of H2, O2 and N2 and their atomic phases reported in the literature, and the dissociation mechanisms were also discussed.

Ambient Humidity Influence on Explosion Characteristics Parameters of Gaseous Epoxypropane

TAN Ru-Mei, ZHANG Qi, HUANG Ying

2013, 27(3): 325-330. doi: 10.11858/gywlxb.2013.03.002

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Abstract:
To evaluate the hazard of gaseous epoxypropane-air explosions, characteristic parameters of gaseous epoxypropane explosion inside 5 L-sphere closed vessel with 40% and 88% relative humidity were measured. The obtained results show that: Maximum overpressures reduce slightly at near optimum explosion concentration, the others make no difference; a major influence of the initial humidity on maximum rates of pressure rise is observed only at 7.0% in the examined ranges of the gaseous epoxypropane concentrations; and the maximum temperature and the maximum rates of temperature rise are slightly influenced by the initial humidity.

Reactive Hydrokinetics in the Early Stage of Shock Initiation of PBX 9501

CHEN Jun, TIAN Zhan-Dong, ZENG Dai-Peng, ZHANG Zhen-Yu, DUAN Zhuo-Ping

2013, 27(3): 331-336. doi: 10.11858/gywlxb.2013.03.003

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Abstract:
Through the application of Lambourn's CIM model, a simplified analytic method was proposed to study the post-shock reactive flow in the case of unknowing the real formula of reaction rate. Based on this method, a more reasonable empirical reaction rate can be extracted to better understand the initial hydrodynamic phenomenon during shock to detonation transition. The method assumes that reaction rate is a function of time. The history and relationship of particle velocity, pressure, extent of reaction and reaction rate can be obtained by combining with experimental particle velocity. The results show that the decrease of particle velocity on impact interface relates with extent of reaction, and peak reaction rate after shock wave appears within the peaks of particle velocity and pressure.

Microstructure and Mechanical Properties of Internal Thread during Cold Extrusion for Q460 High Strength Steel

MIAO Hong, ZUO Dun-Wen, ZHANG Rui-Hong

2013, 27(3): 337-342. doi: 10.11858/gywlxb.2013.03.004

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Abstract:
According to the forming process of internal thread, the microstructure, microhardness and mechanical properties of internal thread surface layer were investigated. The microstructure change and deformation mechanism, harden ability and depth of hardening layers on the crest, the flank and the root of the thread along the layer depth direction were obtained. The results showed that the grains on the surface layers of the thread were refined after the cold extrusion. Fibrous structure of the metal surfaces on the root of thread was pressed to distinguish the grains difficultly, and formed a layer of flown line and smoothly rounded the root to flow from the flank to the crest. The grains on the root were the smallest, followed by the flank and the crest. In the extrusion processes, the microhardness and the tensile strength of the material were increased significantly, and the plasticity and the toughness were decreased. The work-hardening phenomenon greatly increased the surface texture and the mechanical strength of internal thread with cold extrusion.

Application of the MVPPM-Based Fluid-Solid Coupling Method to the Explosion Vessel Simulations

BAI Jing-Song, LIU Kun, ZHANG Hong-Ping, LI Lei, LI Ping

2013, 27(3): 343-351. doi: 10.11858/gywlxb.2013.03.005

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Abstract:
The flow field evolvements inside the explosion vessel volume and the dynamic response of the vessel shell are basic data in designing of the vessel shape, structure and material selection. But for some reason of the vessel large scale, multi-component, high-density ratio and complex structure, and thus the numerical simulation of explosion flow field inside the vessel is very difficult. In this study, we utilized the level set method differentiate the large deformation of the flow field from the small deformation of the vessel, and the Euler MVPPM method and Lagrange were respectively used in numerical calculations. The ghost fluid technology was employed to deal with the fluid and solid at the interface of the physical information. We successfully applied the present method to the ellipsoidal head and the similar spherical explosion vessel simulations.

Cell-Centered Arbitrary Lagrangian-Eulerian Method Based on a Global Grid Generation Technology

LIU Yan, SHEN Wei-Dong, TIAN Bao-Lin

2013, 27(3): 352-360. doi: 10.11858/gywlxb.2013.03.006

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Abstract:
A cell-centered arbitrary Lagrangian-Eulerian method based on a global grid generation technology was developed to simulate compressible multimaterial flows with large deformation. The method adapts well to subdomain grid generation and global grid generation. The static and dynamic numerical examples demonstrated the efficiency of the global grid generation. For the examples with complex regions, the calculated results show the efficiency of the global grid generation.

Effects of Strain Rate and Temperature on Compressive Properties of an Aluminized PBX

CHEN Ding-Ding, LU Fang-Yun, LIN Yu-Liang, JIANG Bang-Hai

2013, 27(3): 361-366. doi: 10.11858/gywlxb.2013.03.007

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Abstract:
Weapons have to face some extremely abominable situations, such as high temperature, high pressure, shock loadings, etc. In such situations, the mechanical properties of the high explosive filled in weapons will decide the level of security of the whole system, making it necessary to get a deep understanding on the mechanical properties of these explosives. In this work, we tested the dynamic compressive properties of an aluminized polymer bonded explosive (PBX) at four temperatures (12, 29, 45 and 62 ℃) by using split Hopkinson pressure bars. Specimens were heated individually before fixed to the bars to get the target temperature. The strain rate was ranged from 250 s-1 to 1 200 s-1. The results show the failure compressive stress is strongly dependent on strain rates and temperatures, while the failure strain almost keeps constant. The failure stress increases obviously with the rise of strain rates and the decrease of temperatures. And a double-linear function is used to fit the compressive failure stress-strain rate temperature relationship. However, this relationship for dynamic compression may become invalid when the temperature is lower than the glass transition temperature.

One-Dimensional Model and Calculation for Fast Cook-off of RDX

TIAN Zhan-Dong, ZHANG Zhen-Yu, LU Fang-Yun, ZHAO Jian-Heng, TAN Fu-Li

2013, 27(3): 367-371. doi: 10.11858/gywlxb.2013.03.008

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Abstract:
Based on gas-phase reaction mechanism, a fast cook-off model was established to study the process of RDX in a confined vessel irradiated by laser. The model considers steel vessel, air gap and condensed explosives. The heat conduction in air gap was used to describe the nonideal thermal contact. The process of decomposition, melting and evaporation in condensed RDX, and the reaction of multi-species and multi-steps in air gap were considered in model calculation by use of finite difference. Results show that the fast cook-off process of RDX can be approximately divided into three stages: inert heating, accumulation of reactants and increase of temperature, and ignition caused by rapid chemical reaction.

Penetration and Perforation of Thick Metal Targets Subjected to Impact by Ogival-Nosed Projectiles

WU Qiao-Guo, WEN He-Ming

2013, 27(3): 372-378. doi: 10.11858/gywlxb.2013.03.009

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Abstract:
An analytical investigation into the penetration and perforation of thick metal targets struck normally by rigid ogival-nosed projectiles over a wide range of velocities was conducted. Based on the assumption that the deformation is localized and that the mean pressure offered by the target materials to resist the projectiles is no longer a constant but a linear function of penetration velocity, equations are derived for predicting the depth of penetration in the targets and the ballistic limits or residual velocity in the case of perforation. Furthermore, the range of applicability of the perforation model is discussed. It transpires that the present model predictions are in good agreement with the test data for thick metallic targets in terms of penetration depth, residual velocity and ballistic limits.

Research on Working Performance of Small Spinning Solid Rocket Motor

YANG Wei-Ling, WANG Zai-Cheng, JIANG Chun-Lan, LI Ming

2013, 27(3): 379-384. doi: 10.11858/gywlxb.2013.03.010

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Abstract:
The small spinning solid rocket motor was employed to perform as the power of the radial twice throwing system. Interior ballistic model of spinning solid rocket motor, in which eroding burn effect was considered, was established. The calculated pressure-time curve was set as initial pressure value for subsequent simulations. Fluid field of nozzle with straight segment was simulated by software of Fluent, whether fluid field was supersonic or not can be identified. Finally static and dynamic tests of spinning solid rocket motor were performed. The tested results of spinning solid rocket motor indicate that spinning solid rocket motor works well at 19 000 r/min and meets the working need.

Analysis of the Onset of Detonation in the DDT Process for Combustible Mixture

WANG Jian, DUAN Ji-Yuan, ZHAO Ji-Bo, TAN Duo-Wang

2013, 27(3): 385-390. doi: 10.11858/gywlxb.2013.03.011

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Abstract:
For comparison with several methods used to define the location of the onset of detonation, several of experiments were performed to study on the deflagration to detonation transition (DDT) for premixed C2H2+2.5O2 mixture in a shock tube. A high-speed digital camera was used to track the velocities of flame, shock, or detonation wave. In this work, six methods were used to define the location of the onset of detonation, and six different results of the DDT run-up distance (LDDT) and the time of the detonation onset (tDDT) were obtained. It is found that the methods based on the flame emission radiation and the growth trajectory of flame, shock, or detonation wave can accurately define tDDT and LDDT. The onset of detonation defined by the other methods based on the speed of detonation wave might result in some error or underestimated values due to the localized explosion taking place just prior to the generation of detonation.

Numerical Simulation of Debris Cloud Characteristics of the Mesh Shields

PANG Bao-Jun, LIN Min, ZHANG Kai, FU Xiang

2013, 27(3): 391-397. doi: 10.11858/gywlxb.2013.03.012

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Abstract:
The hypervelocity impact interaction of the sphere projectile with continuous shield and mesh shield, which were of the same thickness or area density, was investigated numerically. The study was aimed at mastering the hypervelocity impact characteristics of the mesh shield and applying effectively it in development of lightweight shields. The study involved the differences in the morphology and the distribution of momentum, velocity and mass of the debris clouds generated by impacting two kinds of shields. The calculations show that the morphologies of the debris cloud vary with the impact locations when a projectile impact the mesh shield, and there is the linear distribution of debris in the front of debris cloud. Comparison between the continuous shield and the mesh shield with the same thickness, the maximum of momentum density in the mesh shield is higher than that in the continuous shield, while the maximums of momentum density are almost near in the two kinds of shields with the same area density. The mesh shield does not effectively slow the penetration velocity of projectile, but can break it up. The dynamical response of the projectile varies with the shields. Impacting the mesh shield, the main part of debris is at the rear end of the debris cloud, which is different from the case of continuous shield.

Flash X-Ray Radiography for Diagnosing the Ejecta from Shocked Metal Surface

YE Yan, LI Jun, ZHU Peng-Fei, QIAN Wei-Xin, LIU Zhen-Qing, WANG Xiao, LI Xin-Zhu, LI Zuo-You, LI Ze-Ren, ZHONG Jie

2013, 27(3): 398-402. doi: 10.11858/gywlxb.2013.03.013

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Abstract:
The flash X-ray radiography is an important diagnostic tool for the ejecta from shocked metal surface. The influence of metal surface characteristics on the ejecta is a main aspect of numerical simulations and experiments on ejecta phenomena from shocked metal surface. A commercial flash X-ray tube, an X-ray camera and high accuracy synchronization timing system were used to establish a system of ejecta diagnosis. The radiographs of ejecta from the tin targets with different depths of grooves were captured and analyzed. The experimental results showed that (1) the mass ejection of tin targets with grooves presented the quasi-multilayer in vacuum; (2) the zone width and ejecta mass increased with the depth of target grooves in vacuum; (3) the region width and ejecta mass decreased as in gas pressure of 0.1 MPa.

Numerical Study on the Damage of the Coal under Blasting Loads Coupled with Geostatic Stress

MU Chao-Min, PAN Fei

2013, 27(3): 403-410. doi: 10.11858/gywlxb.2013.03.014

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Abstract:
In order to investigate on cracks propagation of the coal under column charge blasting subjected to geostatic stress, the damage constitutive model was established by considering tension and compression. The improved damage constitutive model was embedded in the FEM software to study the mechanics of cracks propagation coupled by blasting loads and geostatic stress. The precision of simulation is proved because the numerical results are in good with model experiments. The results show that the interaction of the compression wave and unloading wave yield cracks in the coal. The cracks are somewhat inhibited by geostatic stress. The direction of cracks is in accordance with the major principal stress.

Experimental Study and Numerical Simulation on Deformation of Diamond and Sample under DAC Loading

JING Qiu-Min, WU Qiang, BI Yan, YU Ji-Dong, XU Ji-An

2013, 27(3): 411-416. doi: 10.11858/gywlxb.2013.03.015

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Abstract:
The compression experiment of molybdenum foil combined with finite element modeling calculation reveals the history of elastic deformation of diamond and elastic-plastic deformation of sample in the pressure gradient method used for measurement of yield strength at high pressures. The influence from elastic compression and cupping of diamond on the in situ thickness measurement and pressure profiles of molybdenum foil is analyzed. The results show that the elastic compression of diamond is very small and reasonable to ignore at least below 31 GPa which is the highest experimental pressure. The cupping of diamond is somewhat notable. But the agreement of pressure profiles and their pressure gradients between calculation and experiment indicate no evident change due to the influence of cupping of diamond below 31 GPa. The cupping finally leads to the contact of corners of culets at 60 GPa. The proposals of experimental design are also given to reduce the influence from cupping deformation of diamond at high pressure.

Experimental Study on Concrete Exposed to High Temperature under Impact Loading

LI Zhi-Wu, XU Jin-Yu, DAI Shuang-Tian, BAI Er-Lei, GAO Zhi-Gang

2013, 27(3): 417-422. doi: 10.11858/gywlxb.2013.03.016

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Abstract:
Based on the traditional spilt Hopkinson pressure bar (SHPB) apparatus, a SHPB system for testing dynamic compressive properties of materials exposed to high temperature was established after adding a tubular electric furnace, and the dynamic compressive stress-strain curves of concrete at 200-800 ℃ were measured using the system. The results show that the SHPB experimental system can be used to test the dynamic properties of concrete exposed to high temperature; Dynamic compressive strength and critical strain of concrete at different temperatures increase with the rise of projectile velocity; Effects of high temperature on dynamic properties of concrete are remarkable: the critical strain increases with the temperature increasing, dynamic compressive strength increases firstly and then decreases slightly, and decreases rapidly after 600 ℃.

Numerical Simulation on Shaped Charge Jet Being Disturbed by Shearing Movement of Four-Layer Spaced Plates

SUN Li-Zhi, LI Zhi-Yuan, Lü Qing-Ao

2013, 27(3): 423-430. doi: 10.11858/gywlxb.2013.03.017

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Abstract:
Numerical simulation with ANSYS/LS-DYNA software was accomplished on metal jet being disturbed by shearing movement of four-layer equivalent spaced plates. Disturbing performance of moving plates was analyzed according to jet rupturing forms, energy losing values, and the penetrating depth in target plate. The effects of the plates-velocity and the impact angle on the disturbing performance were obtained. The obtained results are as follow: the increasing of the plate velocity can improve the disturbing ability on jet; the disturbing efficiency was greater with the plates velocity beneath 100 m/s than over 100 m/s; and the disturbing extent can increase with the increase of the impact angle. All those results are significant for mechanical armoring research.

Effects of Dynamic High Pressure Microfluidization (DHPM) Extraction on the Antioxidation of Flavonoids from Sweet Potato Leaves and Mechanism Studying

TU Zong-Cai, ZHANG Lu, WANG Hui, YE Yun-Hua, LI Zhi, HUANG Xiao-Qin

2013, 27(3): 431-438. doi: 10.11858/gywlxb.2013.03.018

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Abstract:
Effects of dynamic high pressure micro-fluidization(DHPM) in the extraction processing on the antioxidative activities of flavonoid from sweet potato leaves by DHPM in contrast to the traditional ethanol extraction were performed to explore the possible mechanism in combination with the high performance liquid chromatography combined with mass spectrum (HPLC-MS).The results showed that pretreatment by DHPM could promote cell rupture and unfolding of cell membrane, which caused the increase in the extraction rate of total flavonoid. The best result was achieved at 100 MPa with the highest yield of 5.440%0.006%, which was higher by 21.7%, relative to the enthanol extraction. HLPC-MS analysis revealed that pretreatment by DHPM could improve the purity and content of lower polar molecule in extract solvent. 80 MPa and 100 MPa pressurization treatments decreased the antioxidant activity of samples with identical flavonoid content, but had negligible effects on elements and structure of flavonoid. Pretreatment with 120 MPa (SF120 sample) pressurization had the strongest antioxidation with IC50 for DPPH and OH were (15.991.19)mg/L and (0.0930.012)g/L, respectively. The main flavoniods of SF0, SF80 and SF100 are quercetin, 4',7-dimethoxykaempferol, myricetin, ombuin and rhamnocitrin, while, the main flavoniods of SF120 are quercetin, myricetin and ombuin.

Dynamic Compression and Damage Pattern of Hollow Microsphere/Aluminum Alloy Composites

WANG Shao-Heng, YANG Zhen-Qi, GUAN Gong-Shun, PANG Bao-Jun, CHEN Hai-Bo

2013, 27(3): 439-446. doi: 10.11858/gywlxb.2013.03.019

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Abstract:
The hollow microsphere/aluminum alloy composites were fabricated by press infiltration. The dynamic compression behavior of the composites was investigated by using split Hopkinson pressure bar (SHPB). The microstructure of the specimen after compression was characterized by scanning electron microscopy, and the damage patterns of the hollow microsphere were primarily studied. A single-cell model of the composites was established, and the dynamic compression process of the single-cell was simulated by using the LSDYNA explicit finite element software. With dynamic loading, mechanical behavior of hollow microsphere/aluminum alloy composites showed three typical stages: elastic deformation, plastic collapse and densification. With the increasing of the decrement, the hollow microsphere appeared cracks along the meridians, gradually transitioned into the fragmentation of the equator, and eventually collapsed.

High Hydrostatic Pressure Pasteurization Effect and Organoleptic Quality Assessment of Vegetables

DONG Peng, YI Jun-Jie, HUA Cheng, ZHANG Yan, HU Xiao-Song, WU Ji-Hong

2013, 27(3): 447-453. doi: 10.11858/gywlxb.2013.03.020

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Abstract:
In order to improve the quality and prolong the shelf-life of vegetables, the effect of high hydrostatic pressure on pasteurization and quality of vegetables was systematically analyzed and assessed by taking white turnip, lettuce and potato as experimental materials. The results were as follows: The bactericidal effect did not change significantly after treatment of 600 MPa for 5 min. The hardness and resilience of HHP-treated vegetables increased significantly, and Vc content of potato, lettuce and white turnip increased respectively by 49.4%, 17.0% and 23.3%, while E decreased as compared to those with thermal treatment. Sensory evaluation showed that vegetables treated with high hydrostatic pressure were similar to fresh vegetables in color, smell, taste and shape. Therefore, high hydrostatic pressure technology can achieve ideal effects in sterilization, and maintain the quality of vegetables.

Calibration of Standard Hydrophones in the Frequency Range of 20 Hz to 200 kHz at 10 MPa Hydrostatic Pressure

CHEN Yi, HUANG Yong-Jun, FEI Teng

2013, 27(3): 454-460. doi: 10.11858/gywlxb.2013.03.021

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Abstract:
This paper describes the coupler reciprocity method and free-field reciprocity method used for standard hydrophones calibration in the frequency range of 20 Hz to 200 kHz at 10 MPa hydrostatic pressure, and the coupler reciprocity calibration facility working in the frequency from 20 Hz to 3.15 kHz and free-field reciprocity calibration facility working in the frequency from 3.15 kHz to 200 kHz was established on these methods. Standard hydrophones RHC14 and RHS30 were calibrated separately using these facilities, and their sensitivities at 10 MPa hydrostatic pressure was presented. Analyze of measurement uncertainties proved that the expand uncertainty (at k=2) of coupler reciprocity calibration facility was 0.5 dB, and free-field reciprocity calibration facility was 0.7 dB (below 100 kHz) or 0.9 dB (100 kHz to 200 kHz).The construction of these facilities and capabilities sets the test foundation for deep-diving underwater sound devices.

Numerical Simulation of Microscopic Dynamic Behavior in the Copper under Explosively Dynamic Loading

YANG Rui, WANG Jin-Xiang, ZHOU Nan, PENG Chu-Cai, XIE Jun

2013, 27(3): 461-467. doi: 10.11858/gywlxb.2013.03.022

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Abstract:
Voronoi method was adopted to establish the micro-geometry model of polycrystalline copper which can reflect the irregularities of grain geometric shape and grain boundaries. The Tie-Break model was used to reflect the binding characteristics of grain boundary. Then the grains deformation and thermal deposition behavior under explosive dynamic loading were studied from the microscopic view recur to LS-DYNA nonlinear finite element program. Finally, the possibility of grain refining was analyzed by high pressure melting point theory and grain growth theory, and the analysis was proved qualitatively by experimental results. The results show that it is feasible to research grain and grain boundary deformation mechanisms as well as the heat deposition for the shock compressed polycrystalline copper by the numerical simulation method built in this work. Stress concentration is easy to form on the grain boundaries; plastic deformation and temperature rise on the grain boundaries are greater than those of the grain interior. The temperature rise caused by the macro-adiabatic compression and the micro-plastic deformation does not cause grain growth.

Research on Electronic Structure and Optical Properties of Oxygen Atom Adsorbed on GaAs Surface

ZHU Shan-Shan, YIN Chun-Hao, XU Zhen-Kun, WU Cai-Ping, HOU Lei-Tian

2013, 27(3): 468-472. doi: 10.11858/gywlxb.2013.03.023

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Abstract:
Electronic structures and optical properties of oxygen atom adsorbed on GaAs surface have been calculated by using the first-principle based on density functional theory. The results show that the presence of O shifts the energy band to the deep part，with impurity level composed of As 4p and Ga 4p and Tamm surface caused by the splitting of As 4s and Ga 4s appearing in the forbidden band. Adsorption of O changes the distribution of d state and sp state electrons. The existence of O improves the defects in lattice-periodicity and changes the transition of electrons, resulting in the change in optical properties.

2013 Vol. 27, No. 3

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