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Now showing items 49 - 53 of 53

  • Wear behavior and wear debris distribution of UHMWPE against Si3N4 ball in bi-directional sliding

    Ge, Shirong   Wang, Shibo   Gitis, Norm   Vinogradov, Michael   Xiao, Jun  

    Four kinds of wear tracks possibly occurred in the wear of artificial hip joints, including uni-directional sliding, oval curvilinear sliding, double-elliptical sliding, triple-elliptical sliding, were simulated on the UNIT wear tester by using of a Si3N4 ball sliding on the UHMWPE disc under bi-directional sliding motion. The wear behavior and wear particle distribution of UHMWPE in plasma solution lubrication were studied for these sliding motions. The experimental results indicate that the wear mass loss in uni-directional reciprocating sliding is much smaller than those in bi-directional sliding modes. The wear rates of UHMWPE in bi-directional sliding modes are linearly inverse proportional to the defined frequency factor, as agreed with the cross-shear theory. This result suggests that cross-shear movement with larger intersection angles is a significant factor influencing the wear rate of UHMWPE, and the bi-directional sliding path at direction reversals will play an important role on the increasing of UHMWPE wear compared to uni-directional sliding motion. In bi-directional sliding modes, the wear particle distribution range decreases when direction reversal path increases in the sliding motions. So, the complex wear tracks are harmful to the implant joint due to the higher wear and more active wear particles. The particles sizes follow a lognormal distribution. The central size and the peak accumulation of UHMWPE particles decreases and increases against the frequency ratio, respectively, besides the uni-directional reciprocating sliding. These suggest that the intersection angle increasing on sliding path will contribute to the size decreasing of UHMWPE wear particle. Also, cross-points on sliding track will produce wear particles in smaller size. The radius of curvature of the curvilinear paths may be dictating the size reducing of UHMWPE wear particles. The main wear mechanisms are ploughing in uni-directional reciprocation, while plastic deformation, adhesion and fatigue in the bi-directional sliding modes. (c) 2007 Elsevier B.V. All rights reserved.
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  • A Review on the Research Progress of Nano Organic Friction Materials

    Liu, Yang   Bao, Jiusheng   Hu, Dongyang   Ge, Shirong   Yin, Yan   Liu, Tonggang  

    Background: Traditional organic friction materials are difficult to adapt to people's growing technical requirements for stability, safety, comfort and environmental protection in the braking process. With the rapid development of nanotechnology, the brake's organic friction materials meet new opportunities. This article aims to review the research progress of organic friction materials that have applied nanotechnology. Methods: The research progress of nano organic friction materials was reviewed from four aspects in this article. Firstly, this article outlined the development history of friction materials. Secondly, two preparation methods of the nano organic friction material were summarized as by nano modifying of matrix material and by adding nanoparticles into friction material. Thirdly, it was indicated that the nano organic friction material has generally better mechanical, physical properties and tribological performance than traditional organic friction materials. And the main factors that affect the friction and wear performance were analyzed. Finally, the main existing problems in this field were summarized. Results: It was pointed out that the nano organic friction material may be an important developing trend of friction materials. It was also pointed out that the dispersion of nanoparticles must be a key process during preparation. What is more, the improvement mechanisms of performance by nano modifying were explained. And it was considered at the end that the functional friction material with magnetism or self-adsorption may be a leading developoing direction of nano organic friction materials in the future. Conclusion: The findings of this review confirm the excellent performance of nano organic friction materials. It is concluded that the development of a new functional friction material by using the special effect of nanoparticles will be an important developing trend. Few relevant patents to the topic have been reviewed and cited.
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  • Effect of various kinematic parameters of mine hoist on fretting parameters of hoisting rope and a new fretting fatigue test apparatus of steel wires

    Wang, Dagang   Zhang, Dekun   Zhang, Zefeng   Ge, Shirong  

    The effect effect of various kinematic parameters of mine hoist on fretting parameters of the hoisting rope was investigated and a new fretting fatigue test apparatus was designed. A simulation model of the rope tension was presented to examine the role of various kinematic parameters on the rope tension and tension amplitude during lifting. Ranges of fretting parameters of the rope during lifting with different kinematic parameters were determined. The results show that different kinematic parameters induce different modal shapes of the vibrating systems during lifting, which results in distinct ranges of fretting parameters of the rope. (C) 2012 Elsevier Ltd. All rights reserved.
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    Bao, Jiusheng   Yang, Shuai   Ge, Shirong   Han, Peixin   Yin, Yan  

    The trackless rubber tyred vehicle (TRTV) is an important transporting equipment of underground coal mine auxiliary transportation system in the world. Presently, most TRTVs are driven by flameproof diesel engine. However, few researches were focused on their dynamic performance in the past. In this paper, the characterizing parameters and influencing factors of the dynamic performance of a flameproof diesel engine driven TRTV were summarized and discussed firstly. Then the basic dynamic equations of the TRTV were established. Finally, the dynamic performances of the WCQ-3B type TRTV were simulated by ADVISOR. And some important dynamic performance parameters such as maximum speed, acceleration time and maximum gradability were discussed by simulation. What is more, the fuel economy and emission performance of the vehicle were also analysed. It is shown that the dynamic performance of WCQ-3B type TRTV can satisfy the design and usage requirements of underground coal mine.
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  • Effect of displacement amplitude on fretting fatigue behavior of hoisting rope wires in low cycle fatigue

    Wang, Dagang   Zhang, Dekun   Ge, Shirong  

    The effect of displacement amplitude on fretting fatigue behavior of steel wires in low cycle fatigue at two cyclic strain levels was investigated. Evolutions of normalized tangential force and morphologies of contact scars were investigated to examine the wear mechanisms. Fretting regime and fretting fatigue life were explored. Acoustic emission technique was utilized to reveal wire failure mechanisms. The results show that an increase of displacement amplitude increases normalized tangential force but decreases the fretting fatigue life. Fretting contact conditions are all mixed fretting regimes. Fretting damage and crack nucleation and propagation accelerate with increasing displacement amplitude. (C) 2012 Elsevier Ltd. All rights reserved.
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