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Li M.S.,South China University of Technology | Du Q.G.,Guangzhou Mechanical Engineering Research Institute
Advanced Materials Research | Year: 2014

By the field test, we carried on the physicochemical tests, the lubrication performance test, the ferrographic analysis and ICP tests for different mileage of CVTF, we also ran the electron microscope analysis of the key components of steel belt of CVT's friction pair and bevel pulley. The transformation law of CVTF' lubrication, the inoxidizability, the friction durability friction, the antifriction performance, the attenuation characteristics of functional elements and the abrasion mechanism of Cone wheel and steel belt are investigated.The result showed that there was the presence of extreme pressure film on the surface of friction pair, the physicochemical parameters of CVTF changed very small, the wear metal elements in petrol within 3000km increased slowly. © (2014) Trans Tech Publications, Switzerland. Source

Ye S.,South China University of Technology | Zeng X.,Guangzhou Mechanical Engineering Research Institute
Tribology and Lubrication Technology | Year: 2014

The friction and wear properties of polytetrafluoroethylene (PTFE) and its composites with fillers such as bronze, glass fiber, carbon fiber, carbon, graphite, and polymer were studied at ambient temperature and high temperature. The wear resistance and hardness were enhanced by the fillers. Results showed that the wear resistance of all composites was much higher than that of pure PTFE. Pure PTFE has the lowest friction coefficient at ambient temperature (temperature: 23 ± 2°C, humidity: 50 ± 10%) but highest friction coefficient at high temperature (above 100°C). The PTFE composite filled with bronze showed the best wear resistance at ambient temperature but the poorest wear resistance at high temperature. The carbon-graphite- or polymer-filled PTFE composite showed a lower friction coefficient and moderate wear resistance at both ambient and high temperature. Source

Jia X.,Tsinghua University | Guo F.,Tsinghua University | Huang L.,Guangzhou Mechanical Engineering Research Institute | Salant R.F.,Georgia Institute of Technology | Wang Y.,Tsinghua University
Tribology International | Year: 2013

bstract This study investigates the effects of structure, material parameters and assembly conditions on the reverse pumping rate and friction torque of the radial lip seal by using a mixed elastohydrodynamic lubrication model. The orthogonal array method is used to make a numerical experiment plan for eight parameters, which are identified as eight control factors. Each factor has five levels. The significance of each parameter on the reverse pumping rate and friction torque of the radial lip seal is evaluated by range analysis and F-test. As a result, optimal values of eight parameters are suggested. The seal with this set of optimal values has a higher reverse pumping rate and lower friction torque than those of a previously-designed seal. © 2013 Elsevier Ltd. Source

Song D.,GuangZhou Research Institute of Nonferrous Metals | Qi W.,GuangZhou Research Institute of Nonferrous Metals | Liang T.,Guangzhou Mechanical Engineering Research Institute | Wang H.,GuangZhou Research Institute of Nonferrous Metals | Zhou N.,GuangZhou Research Institute of Nonferrous Metals
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2012

Four groups of friction stir welded 6061-T6 aluminum alloy were artificial aged, and the microstructure and mechanical properties influence law and mechanism of joint with different aging process were investigated by OM and SEM. The results showed the morphology of the weld cross-section constituted of three typical areas. The grain morphology of the weld zone had no significant change by aging treatment, but grain boundaries were more clear and intragranular precipitates increased significantly than the natural aging joint. The joint strength and microhardness improved with the time of artificial aging treatment increased, and the range of improvement gradually decreased with the holding time. The joint exhibited excellent mechanical properties when holding time was 8 h. The tensile strength passed 265 MPa, about 93.0% of the base metal, and nugget zone microhardness reached to 90 HV, about 90% of the base metal. The second phase particles gradually precipitated from matrix which solid solution during the welding process, joint strength and microhardness increased significantly due to dispersion strengthening effect. The precipitate particles reduced gradually with the aging time, and the strengthening effect gradually weakened. The weak area of joint was located in heat affected mechanical zone of retreating side, and the lowest microhardness value was approximately 75% of the base material. The tensile fracture appeared a typical cut-off with an angle of about 45 ° stretched angle and smooth microstructure. The joint fracture dimples of aging treatment exhibited larger and shallower compared with natural aging, and the plastic reduced slightly. Source

Guo F.,Tsinghua University | Jia X.,Tsinghua University | Huang L.,Tsinghua University | Huang L.,Guangzhou Mechanical Engineering Research Institute | Wang Y.,Tsinghua University
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2014

A mixed lubrication model of rotary lip seals using a statistical approach with flow factors based on reverse pumping mechanism has been developed. The model consists of coupled fluid mechanics analysis, asperity contact analysis and deformation analysis. The oil film pressure and shear stress are obtained from solving the Reynolds equation. Using the GREENWOOD-WILLIAMSON surface contact model computes the contact pressure between the lip and shaft. The deformation analysis of lip seals is carried out using the influence coefficient method. Applying the mixed lubrication model to a typical lip seal, the pumping rate and friction torque are the two most important factors of evaluating seal characteristics, which are the output results of theoretical simulation. Most important, the pumping rate and friction torque are measured with bench test designed by the authors. The measurement of these two factors verifies the validity of the mixed lubrication model. For the reverse pumping action of rotary lip seals is resulted from the surface asperities, the influence of roughness on the pumping rate, friction torque and the contact area are carried out by using the verified theoretical mixed lubrication modle. © 2014 Journal of Mechanical Engineering. Source

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