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- 저자 : Xiaokai Yu (검색결과 4 건)
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Life extension analysis of high speed ball bearing based on multi-parameter coupling
Guang Zeng,Chunjiang Zhao,Xiaokai Yu,Qiang Bian,Zhigang Xiao,Bingyang Liu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.4
The internal contact nonlinear characteristics caused by the quasi-static properties of high-speed ball bearing is taken as a breakthrough point. Based on the L-P fatigue life theory, the bearing parameters and the preload load are used as the constraint variables to establish an overall bearing life extension model. Then, combined with the influence of geometric parameters on the osculation, the influence mechanism between spin-to-roll ratio and the life of the bearing are studied under the individual variation of the geometric parameters. Finally, the variation law of the bearing life, frictional heat generation and spin-to-roll ratio under the coupling changes of various parameters, and the priority of each parameter on the bearing life sensitivity, are investigated. The results show that the bearing life could be prolonged when the initial contact angle and the number of rolling elements increase but the inner and outer raceway curvature radius coefficients of the bearing and the preload force reduce. And the priority order of each parameter to bearing life sensitivity is as follows: the inner and outer raceway curvature radius coefficients shows the strongest influence on the bearing life, followed by the number of balls, and then the initial contact angle. This research provides a reliable theoretical basis for the design of high-speed ball bearings and life extension technology.
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Analysis of high speed bearing based on virtual rods model
Guang Zeng,Chunjiang Zhao,Xiaokai Yu,Yufeng Yin,Zhigang Xiao,Yijie Feng 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5
The traditional high-speed ball bearing analysis is based on the quasi-static model proposed by Jones-Harris (J-H). This study gives another bearing analysis model based on the relative position of the ball center and the centers of curvature of the raceway grooves, described by the virtual rods. Specifically, the load and deformation of the virtual rods are determined according to the principle of force transmissibility, the translation theorem of a force, and elastic-contact deformation between steel ball bearings and raceway grooves. And the iterative variables such as the axial, radial and angular deformations are gradually introduced into the calculation model to solve the force and kinematic parameters under pure axial load, bidirectional and tri-directional combined loads. The correctness of the virtual rods model is verified by the contact angle for axial and bidirectional load. The influence of gyroscopic moment and raceway grooves control parameter on the actual contact angle under tridirectional loading conditions are calculated and analyzed respectively. The proposed model uses fewer equations and lower-dimension parameters than those used by the traditional highspeed ball bearing analysis method, improves the solution rate of the equations.
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Lin, Chao,Shinde, Sambhaji S.,Jiang, Zheng,Song, Xiaokai,Sun, Yu,Guo, Linli,Zhang, Hao,Jung, Jin-Young,Li, Xiaopeng,Lee, Jung-Ho The Royal Society of Chemistry 2017 Journal of materials chemistry. A, Materials for e Vol.5 No.27
<▼1><P>A “three birds one stone” strategy for preparing 1D N-doped porous carbon nanotubes embedded with Co@CoOx nanoparticles results in the unprecedentedly high-rate Zn–air batteries.</P></▼1><▼2><P>In this work, we demonstrate a “three birds one stone” strategy for preparing 1D N-doped porous carbon nanotubes embedded with core–shell Co@CoOx nanoparticles (Co@CoOx/NCNTs) from bimetallic ZnO@Zn/Co-ZIF nanowires. The ZnO nanowires played three roles: (i) ZnO acted as a template for 1D metal–organic framework (MOF) growth, (ii) <I>in situ</I> evaporation of Zn during pyrolysis prevented the aggregation of the carbon framework and benefited the formation of hierarchical pores, and (iii) the excess oxygen species released from ZnO <I>in situ</I> reacted with metallic cobalt nanoparticles during pyrolysis, leading to the configuration of a Co@CoOx core–shell structure. The as-prepared 1D Co@CoOx/NCNTs exhibited excellent oxygen reduction reaction performance, including a high kinetic current (4.6 times better compared to 20 wt% Pt/C at 0.7 V), a low Tafel slope of 80 mV dec<SUP>−1</SUP>, outstanding stability, and strong tolerance to CH3OH crossover. The assembled Zn–air batteries with Co@CoOx/NCNTs yielded high open-circuit voltage (1.52 V), superior stability (over 100 h of operation), and unprecedented rate performance that ranged from 1 to 500 mA cm<SUP>−2</SUP>, while existing batteries have never achieved a galvanostatic discharge current density larger than 300 mA cm<SUP>−2</SUP>. Such exceptional rate capability was ascribed to the formation of a uniform interconnected nanotube network, facilitated electron transport, and an enlarged electrochemically accessible surface area in the unique 1D porous tubular structure.</P></▼2>
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