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Description to wear debris boundaries by radar graph fractal method

Chinese Science Bulletin 2007年第16期52卷 2285-2290页

作者： LIU HongTao1,2.& GE ShiRong1 1 Institute of Tribology and Reliability engineering,china University of {2. & technology,xuzhou 2.1008,china 2.college of mechanical and electrical engineering,china University of {2. & technology,xuzhou 2.1116,china Institute of Tribology and Reliability engineering China University of Mining & Technology Xuzhou 221008 China

In this paper,radar graph fractal method is introduced to describe wear debris boundaries. Research results show that it is a nice way to describe wear debris boundaries. Since the longest axis is selected as the first coordinate axis,its center point selected as the center point of the radar graph,and the co-ordinate value of wear debris boundary selected as the measure parameter,the limitations existing in Yard fractal measure method can be avoided. For any wear debris,its radar graph fractal dimension value is one and only,and as the wear debris shape changes from round to strip,the radar graph fractal dimension value also changes from low to high,showing strong uniqueness and independence. Due to the fact that the researched wear debris is gotten in different wear states,the results also prove that radar graph fractal dimension value is correlated with frictional pairs work condition and wear state. Radar graph fractal method is compared with Yard fractal measure methods,and results show that ra-dar graph fractal dimension values gotten from different wear debris have enough value grads to avoid effect of errors,and provide higher sensitivity for wear debris shape. This paper also discusses the influencing factors for radar graph fractal method. With the increase of the decomposing degree value,the radar graph fractal dimension tends to keep stable at one certain value,showing the typical characteristic of the fractal theory. All this proves that radar graph fractal method is an effective description method for wear debris boundaries.

关键词：磨粒边界雷达图表分形法

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Effect of Preparation Methods on mechanical Properties of PVA/HA Composite Hydrogel

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Journal of Bionic engineering 2010年第3期7卷 235-243页

作者： Dekun Zhang~1, Junjie Duan~1, Dagang Wang~2. Shirong Ge~2.1. School of Materials Science and engineering, china University of {2. and technology xuzhou 2.1116, P. R. china 2. School of mechanical and electrical engineering, china University of {2. and technology, xuzhou 2.1116, P. R. china School of Materials Science and engineering China University of Mining and Technology Xuzhou P. R. China School of mechanical and electrical {2. China University of Mining and Technology Xuzhou P. R. China

Poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogel specimens were prepared with 15% PVA and 1%,2., 3%, 4% and 5% HA by repeated freezing-thawing. The tests of static and dynamic mechanical properties were carried out todiscuss the influence of different contents of HA and freezing-thawing cycles on the mechanical properties of PVA/HA compositehydrogel. The results of static mechanical tests showed that the PVA/HA composite hydrogel with 3% HA and ninefreezing-thawing cycles had excellent stress relaxation properties, higher relaxation ratio, lower stress equilibrium value andpresented better properties of creep and recovery. The results of dynamic mechanical test showed that the PVA/HA compositehydrogel with nine freezing-thawing cycles had higher storage modulus and loss modulus, so was the PVA/HA compositehydrogel with 3% HA.

关键词： composite hydrogel HA contents freezing-thawing cycles static properties dynamic properties

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Relations between thickness of UHMWPE’s wear debris and positive pressure of tribological system

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Chinese Science Bulletin 2008年第9期53卷 1435-1443页

作者： LIU HongTao1,2.3 & GE ShiRong1,3 1 Institute of Tribology and Reliability engineering, china University of {2. & technology, xuzhou 2.1116, china 2.college of mechanical and electrical engineering, china University of {2. & technology, xuzhou 2.1116, china 3 Biotribology Center, State Key Laboratory of Tribology, xuzhou 2.1116, china Institute of Tribology and Reliability engineering China University of Mining & Technology Xuzhou 221116 China college of mechanical and {2. engineering China University of Mining & Technology Xuzhou 221116 China Biotribology Center State Key Laboratory of Tribology Xuzhou 221116 China

MiaoXAM2.5X-50X Ultrahigh Precision Surface 3D Profiler is introduced to research the relations be- tween thickness of UHMWPE’s wear debris and positive pressure of tribological system. Research re- sults show that thickness of wear debris owns evident classification, and the first grade thickness math model and the second grade thickness math model are built. By the second grade thickness math model, the true force condition in the tribological system can be gotten, and the model can be used as a tool to modify simulating parameters of the tribological system, and it is an important inspecting method to the airtight system which cannot be examined in real time. The first grade thickness math model can describe the true working load and surface condition of work piece in the tribological sys- tem, and is an effective description method for the running condition of frictional pairs. The research results at different lubricating conditions testify the relations between thicknesses of wear debris and positive pressure of the tribological system. The fractal relation between maximal thickness of wear debris and positive pressure is discussed. The conceptions of the immutability principle and charac- teristic granularity of wear debris thickness are brought forward and discussed. In conclusion, as a stable tribological parameter owning mechanical theory basis, wear debris thickness will play an im- portant part in fault diagnosis, especially for the airtight system such as artificial joint.

关键词：摩擦学磨损面厚度分形数学模型

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Transient temperature field of a friction pair in a HVD device of a belt conveyor

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mining Science and technology 2010年第6期20卷 904-907页

作者： XIE Fangwei, HOU Youfu School of mechanical and electrical {2., china University of mining & technology, xuzhou 2.1008, china School of mechanical and electrical {2. China University of Mining & Technology Xuzhou 221008 China

To show the distribution of a temperature field on a steel disk and to prolong the service life of a friction pair in a Hy-dro-Viscous Drive (HVD) device, a theoretical model of a transient temperature field was established, based on the theory of heat conduction. This theoretical model was solved using a finite element method. The results show that the surface temperature of the steel disk does not increase consistently as a function of the radius; the highest temperature appears short of the maximum radius. The relationship between the surface temperature and the mixed friction time is exponential. With a friction time of 15 s, the tem-perature reached 465.9 °C. Simultaneously, the internal thermal stress is larger than the yield stress of the material, causing a warping deformation of the steel disk. The largest axial deformation is 0.32.mm. The results of the experiment suggest that the de-formation is the same as that obtained from numerical simulation. Therefore, deformation of the steel disk must be considered dur-ing the study of the characteristics of a HVD.

关键词： hydro-viscous steel disk temperature field deformation numerical simulation

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Parameters Relevant to Bubble Detachment when Gas-injecting into Polymer Melt Flow Field

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Journal of Wuhan University of technology(Materials Science) 2005年第1期20卷 68-71页

作者：陈再良 college of mechanical and {2. engineering Soochow University Suz hou 215021 China

The bubble deformation processes were reported when gas was injected into polyme r melt flow field in another paper, the experiments showed that the deformation was severely affected by the volume of the bubble, and in turn, for the different bubbles, several different deformation processes were presented d uring their movement along the flow channel. In addition, we could find that the magnitude of the bubble volume was dependent upon the pressure difference of th e gas injection pressure and the melt pressure. In this paper, more experimental conditions were changed to investigate the parameters relevant to the detachmen t of bubbles from the injection nozzle. The experimental results show that the p ressure difference, the melt flow velocity as well as the melt pressure were all critical for the parameters, such as the bubble detachment time, the maximum bu bble diameters and the magnitude of the bubble volume. The morphology changes of bubble were very large when the flow field was abruptly changed, and the situat ions were more complicated.

关键词： bubble morphology detachment time geometry parameters flow field

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Analysis on Tribological Properties of Potentially New Friction Material with Response Surface Method

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Journal of Wuhan University of technology(Materials Science) 2011年第3期26卷 499-503页

作者：徐蕾 School of mechanical and electrical {2. China University of Mining & Technology

The tribological properties of newly developed friction material were evaluated by statistical analysis of the major affecting *** material for investigation was non-metallic friction material synergistically reinforced with aramid fibre and CaSO 4 whisker,which was developed for hoisting applications in coal *** response surface method（RSM）was employed to analyze the material performances affected by the independent and interactive effect of the factors under the normal working condition and severe working condition,*** showed that under the normal working condition,the newly developed material exhibited stable tribological properties which were insensitive to the test *** under the severe working condition,the sliding velocity was the most dominant factor affecting the friction ***,compared to the commercially available material,the modified material showed superior wear resistance and thermal stability.

关键词： tribological properties friction material response surface method wear

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Research on the Long Time Swelling Properties of Poly (vinyl alcohol)/Hydroxylapatite Composite Hydrogel

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Journal of Bionic engineering 2009年第1期6卷 22-28页

作者： De-kun Zhang~(1,3), Da-gang Wang~2. Jun-jie Duan~(1,3), Shi-rong Ge~(2.3)1. School of Materials Science and engineering, china University of {2. and technology, xuzhou 2.1116, P. R. china2. School of mechanical and electrical engineering, china University of {2. and technology, xuzhou 2.1116, P. R. china3. Biotribology Center, National Key Laboratory of Tribology, Tsinghua University, Beijing 100083, P. R. china School of Materials Science and engineering China University of Mining and Technology Xuzhou P. R. China Biotribology Center National Key Laboratory of Tribology Tsinghua University Beijing P. R. China School of mechanical and electrical {2. China University of Mining and Technology Xuzhou P. R. China

Poly(vinyl alcohol)/hydroxylapatite(PVA/HA)composite hydrogel was prepared by repeated freezing and *** water loss properties of the resultant hydrogel were investigated by using optical *** time immersion tests of PVA/HA composite hydrogel were carried out in the diluted calf serum solution to study the change laws of swelling properties with the freezing-thawing cycles and HA *** micro-morphologies of PVA/HA composite hydrogel after long time immersion were observed by means of the high-accuracy 3D *** results show that the swelling process of PVA/HA composite hydrogel is the converse process of its water *** time swelling ratio curves of PVA/HA composite hydrogel in the calf serum solution are manifested as four stages of quick increase,decrease,slow decrease and stable balance,and its equilibrium swelling ratio decreases with the increase of freezing-thawing cycles and HA *** is revealed that the network structure of the composite hydrogel immersed for a long period is significantly improved with the increase of HA content. Perfect network structures of PVA/HA composite hydrogel as well as full and equilibrium tissues after swelling equilibrium are obtained when the HA content is 3% and the number of freezing-thawing cycles is 7.

关键词： poly (vinyl alcohol) hydroxyapatite composite hydrogel swelling property morphology

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Kinetics analysis of volume phase transition of intelligent neutral thermo-sensitive hydrogels

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Science china(Physics,Mechanics & Astronomy) 2008年第5期51卷 532-540页

作者： WANG XiaoGui1 & LI YiQuan2.1 college of mechanical {2.,Zhejiang University of technology,Hangzhou 310032.china 2.School of mechanical & Electronic {2.,Changchun University of Science and technology,Changchun 13002.,china college of mechanical {2. Zhejiang University of Technology Hangzhou China School of mechanical & Electronic engineering Changchun University of Science and Technology Changchun China

In this work,utilizing the first law of thermodynamics and the Flory mean-field theory,the kinetic deformation studies concerning the volume phase transition of the neutral thermo-sensitive hydrogels were performed *** hydrogel was assumed as a biphasic mixture medium in the framework of the continuum mixture *** the energy conservation of the thermodynamics system of the hydrogel,the governing equations for the kinetics of the nonlinear large deforma-tion were *** explicit analytical expressions of the effective stress tensor and the chemical potential of the fluid of the thermo-sensitive hydrogel PNIPA were also obtained from the Helmholtz free energy,which can model the steady-static volume phase transition quantitatively.

关键词： thermo-sensitive hydrogel volume phase transition effective stress energy conservation

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The characteristics of arc beam shaping in hybrid plasma and laser deposition manufacturing

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Science china(Technological Sciences) 2006年第2期49卷 238-247页

作者： ZHANG Hai’ou1, QIAN Yingping1,3, WANG Guilan1 & ZHENG Qiguang2.1. School of Material Science and technology, Huazhong University of Science and technology, Wuhan 430074,{2. 2. Institute of Laser technology and engineering, Huazhong University of Science and technology, Wuhan 430074,{2. 3. mechanical engineering college, Hubei University of technology, Wuhan 430068,{2. School of Material Science and technology Huazhong University of Science and Technology

As a new direct metal prototyping technology,the hybrid plasma and laser deposition manufacturing (PLDM) is proposed in this paper. In order to figure out the characteristics of plasma arc beam and mould in the PLDM process of high temperature alloy, the high speed CCD camera is used to obtain the picture around the plasma arc. Afterwards the sketch of picture is clearly obtained. And the effect of laser parameter, such as average power, pulse width, pulse repetition frequency and the angle between laser beam and plasma arc beam on the plasma arc appearance, is studied experimentally. The results show that the modality of plasma arc beam is markedly influenced by laser beam. And the improvements of shape precision and surface state of the layer deposited by PLDM are confirmed.

关键词： plasma hybrid laser, direct deposition, plasma arc beam, molding character, high-temperature alloy.

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Microstructure and formation mechanism of twins of laths of austenite with high nitrogen

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Science china(Technological Sciences) 2007年第6期50卷 755-764页

作者： WU CuiLan1,2.& LUO ChengPing2.1 Center for High Resolution Electron Microscopy, college of Materials Science and engineering, Hunan University, Changsha 410082.{2. 2.college of mechanical engineering, South{2. University of technology, Guangzhou 510641,{2. Center for High Resolution Electron Microscopy College of Materials Science and Engineering Hunan University college of mechanical {2. South China University of Technology

The microstructure of composite diffusion layer of the nitrided and chromized 0.2. carbon steel is investigated using TEM and EDS. It is found that laths of austenite with high nitrogen (γ N) precipitate from α-ferrite matrix in the deeper zone of the diffusion layer. These γ N laths are all twins, with their {111} twinning planes parallel to the lath axis, thus forming a characteristic "back-to-back" morphology. There are two types of γN lath. The first is a genuinely {111} twin, and γ N and α keep the accurate K-S relationship, and each γ N and α form a sharp and smooth γ N/α inter- face of {335}γN//{341}α, namely habit plane {335}fcc. The second is a pseudo-twin, with micro-twins {111} or faults formed within the two twin components. Localized lattice deformation (relaxation) seems to have occurred at the interfaces of the second type of γ N due to the formation of micro-twins or faults within the twin components. These micro-twins or faults make the orientation relationship (OR) between each of the γN and the α-matrix deviate from the accurate K-S OR, and the OR between two γ N twin components deviate from the genuine {111} twin relation- ship. In addition, the γ N/α interface of the second type of γ N is not as sharp or smooth as that of the first one.

关键词： austenite containing nitrogen, twins, steel 2., nitriding, composite chromizing

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