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Friction moment analysis of space gyroscope bearing with ribbon cage under ultra-low oscillatory motion

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Chinese Journal of Aeronautics 2014年第5期27卷 1301-1311页

作者： Jiang Shaona Chen Xiaoyang Gu Jiaming shen xuejin Research Institute of Bearings Shanghai University Shanghai Tianan Bearing Co. Ltd

This paper presents the model of calculating the total friction moment of space gyroscope ball bearings which usually work under ultra-low oscillatory motion and are very sensitive to the friction moment. The aim is to know the proportion of the friction moment caused by each frictional source in the bearing＇s total friction moment, which is helpful to optimize the bearing design to deduce the friction moment. In the model, the cage dynamic equations considering six degree-of-freedom and the balls dynamic equations considering two degree-of-freedom were *** good trends with different loads between the measured friction moments and computational results prove that the model under constant rate was validated. The computational results show that when the speed was set at 5 r/min, the bearing＇s maximum total friction moment when oscillation occurred was obviously larger than that occurred at a constant rate. At the onset of each oscillatory motion, the proportion of the friction moment caused by cage in the bearing＇s total friction moment was very high, and it increased with the increasing speed. The analyses of different cage thicknesses and different clearances between cage pocket and ball show that smaller thickness and clearance were preferred.

关键词： Ball bearings Cage thicknesses Clearances Dynamic equations Friction moment Frictional sources Oscillatory motion

Study on a New Type of Lubricating Oil for Miniature Bearing Operating at Ultra-low Temperature

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China Petroleum Processing & Petrochemical Technology 2018年第1期20卷 93-100页

作者： Wang Zhiheng Tao Dehua shen xuejin Chen Xiaoyang School of Mechatronic Engineering and Automation Shanghai University

The synthetic oil has been extensively used in the miniature bearing thanks to its good low-temperature fluidity. However, most of commercial synthetic oils cannot meet the requirements for operating at ultra-low temperature, demanding that the lubricating oil should flow below -60℃ with its ISO VG being greater than 10 mm^2/s. In this paper, the relationships between the structures of the ester, polyether, and silicone oils, and low temperature fluidity were investigated. The results showed that the low-temperature fluidity of oil having a shorter molecular chain length and a smaller molecular weight became better. Moreover, except the silicone oil, other synthetic oil cannot reach the requirements for working at ultra-low temperature. Silicone oil has good low-temperature properties, but it has poor lubricating properties in an environment where steel is sliding against steel. Then based on the analytical results, a new type of non-Newtonian oil was developed. The test results showed that the fluidity of the newly developed oil at below -60℃ is much better than that of the commercial 4123, 4129 ester type aviation lubricants. In addition, it has good lubricating performance, which is much better than that of the silicone oil. The non-Newtonian oil demonstrates a promising prospect for application in miniature bearings operating at low load and ultra-low temperature.

关键词： miniature bearing non-Newtonian fluid lubricant low temperature fluidity

A Coupled Cavitation Model in an Oscillatory Oil Squeeze Film

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Computer Modeling in Engineering & Sciences 2020年第4期123卷 129-152页

作者： Xu Liu Xiaoyang Chen Rongyu Kang xuejin shen Ben Ni Shanghai University Shanghai200072China Ford Motor Company DearbornMI 48126USA

In this paper,the oscillatory oil squeeze film is taken as a research object,and a coupled cavitation model based on the theory of bubble dynamics and hydrodynamic lubrication is used and a specific method of numerical calculation is *** the parallel-plate squeeze film test apparatus is used to validate the coupled cavitation *** pictures of the cavitation were captured by a high-speed camera and then processed to obtain the variation of the cavitation area in *** with the experimental results,the model can successfully predict the process of generation and development of *** the same time,the pressure variation calculated by the model is in good agreement with the experimental data and the value of negative pressure is close to the *** this basis,three new parameters that are related to bubble dynamics are studied by comparing the pressure and cavitation area variation in an oscillating squeeze oil *** results show that surface dilatational viscosity,initial radii of cavitation nuclei and number of bubbles per unit area have a significant influence on the generation time of the cavitation,the maximum tensile stress that the oil film can withstand,and the speed of the cavitation collapse respectively.

关键词： Bubble dynamics oscillatory oil squeeze film cavitation

Experimental investigation of EHD grease lubrication in finite line contacts

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Friction 2019年第3期7卷 237-245页

作者： Zhijian WANG xuejin shen Xiaoyang CHEN Dehua TAO Lei SHI Shuangbiao LIU School of Mechatronics Engineering and Automation Shanghai UniversityShanghai200072China Caterpillar Inc 100Sl White BlvdLaGrangeGA30241USA

The objective of this study was to investigate the grease-lubricated film-forming mechanisms in the finite line contact and to improve the grease-lubricated finite line contact’s film-forming *** elastohydrodynamic lubrication(EHL) test rig with two interferometry microscopes,which could simultaneously monitor two different contact locations in the finite line contact,was constructed in order to study the influences of the grease thickener formulation on the film thickness and lubrication *** using the relative light intensity method,the thickness maps of the grease-lubricated film were calculated from the interferometer images captured by the two *** test results revealed that the grease thickener’s formulation had remarkable effects on film formation and the perturbation of film *** the lithium-based grease,the film’s thickness near the two ends of the roller was prone to severe perturbation caused by the conglomeration of clumps that were hard to *** the aluminum-complex-based grease,the fibers tended to accumulate in the middle of the roller rather than at the two *** urea-based grease could be easily sheared into smaller *** addition to the straight-line profile rollers,the logarithmic profile rollers were tested and found to effectively enhance the axial grease flow,increase the axial shear stress,and thus shear more fibers into particles within the contact area.

关键词： EHL finite line contact grease film thickness

ELASTOHYDRODYNAMIC LUBRICATION OF LOGARITHMIC PROFILE ROLLER CONTACTS

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Chinese Journal of Mechanical Engineering 2001年第4期14卷 347-352页

作者： Chen Xiaoyang, shen xuejin (Research Institute of Bearings,Shanghai University) Xu Wen, Ma Jiaju (Zhejiang University) 上海大学上海浙江大学浙江

An account of numerical solutions to the isothermal and flooded elastohydrodynamic lubrication(EHL)of a logarithmic profile roller,which is rolling over a flat plane,is given The analysis takes account of sideways flow of lubricant in the inlet region of the contact When the results are presented in suitable non dimensional groups,it is shown that more uniformly pressure and shape of the film distributing in axial direction is taken place under light loading As the increase of the load,the end closure is displayed and the oil pressure rises sharply at the ends The seal action formed by the end closure makes the film thickness a little And the minimum film thickness is transferred from the central to the ends and the value is reduced rapidly As the increase of the speed,the end closure becomes much serious The optimum crowning value obtained in EHL state is larger than the design value obtained in elastostatic contact state for the same working conditions In order to verify the correctness of theory,optical interferometry is applied to measure the oil film thickness between a logarithmic profiled roller and a glass plate under pure rolling conditions It is found the agreement between numerical solutions and experiments is very good.

关键词： Elastohydrodynamic lubrication(EHL) Logarithmic profile roller Finite line contacts Optical interferom etry measurement

Elastohydrodynamic lubrication properties and friction behaviors of several ester base stocks

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Friction 2015年第3期3卷 243-255页

作者： Yifeng HE Thomas J.ZOLPER Pinzhi LIU Yuzhen ZHAO Xingliang HE xuejin shen Hongwei SUN Qinghua DUAN Qian WANG Research Institute of Petroleum Processing SINOPECBeijing 100083China Department of Mechanical Engineering Northwestern UniversityEvanston IL 60208USA Department of Mechanical Engineering University of WisconsinPlatteville WI 53818USA Chongqing Branch of Lubricant Company SINOPECChongqing 400039China School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200072China

This paper reports a series of studies on the lubricant properties,elastohydrodynamic film thickness,and coefficients of friction of several commercially available ester base stocks,i.e.,diisooctyl phthalate(DIOP),diisodecyl phthalate(DIDP),diisotridecyl phthalate(DITDP),diisooctyl sebacate(DOS),diisotridecyl sebacate(DTDS),trihydroxymethylpropyl trioleate(TMPTO),and pentaerythritol tetraoleate(PETO).The results include densities and viscosities from 303 to 398 K,and elastohydrodynamic lubricant film thicknesses and friction in the boundary,mixed and full-film lubrication regimes measured at several temperatures,loads,and *** ester base stocks have different lubrication abilities owing to their chain lengths,geometric configurations,and molecular *** study provides quantitative insight into the use of ester-based lubricants for low friction through the entire lubrication regime(boundary to full film)by utilization of suitable type and size of the ester base stocks.

关键词： ester viscosity elastohydrodynamic lubrication friction synthetic base stocks

Tribological problems of surface IC processed MEMS

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Science China Mathematics 2001年第S1期44卷 443-448页

作者： CHEN Xiaoyang shen xuejin LU Jingtang School of Mechatronical Engineering and Automation, Shanghai University, Shanghai 200072, China Shanghai Univ Sch Mechatron Engn & Automat Shanghai 200072 Peoples R China

Successful microactuators of simple mechanics on silicon chip are a prerequisite formonolithic microrobotic systems. Recent development in microelectromechanical systems (MEMS)has led to the success in building new types of microactuators. Based on the design of microgrip-pers and linear microvibromotor, which were fabricated using surface micromachining, the analysisof contact pairs and opposite movement forming of moving elements is given in this paper. Thesource and mechanism of tribology of MEMS are discussed. Associated with the developing his-tory of macro-machine, several research methods and possible existing problems about the tribol-ogy of surface IC processed MEMS are pointed out.

关键词： MEMS surface micromachining tribology silicon

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静电梳状硅微单侧直脚谐振器的力学性能

机械工程学报 2009年第5期45卷 49-56页

作者：沈雪瑾上海大学机电工程与自动化学院上海200072

建立单侧支撑直脚型静电梳状硅微谐振器的三次超静定简化力学模型,给出该模型中谐振频率、弹性系数和横向最大位移的计算公式。与五次超静定系统的双侧支撑直脚型静电梳状硅微谐振器的各力学性能参数的计算公式对比发现它们有显著差别... 详细信息

建立单侧支撑直脚型静电梳状硅微谐振器的三次超静定简化力学模型,给出该模型中谐振频率、弹性系数和横向最大位移的计算公式。与五次超静定系统的双侧支撑直脚型静电梳状硅微谐振器的各力学性能参数的计算公式对比发现它们有显著差别。分析表明,与双侧支撑直脚型静电梳状硅微谐振器显著不同,单侧支撑直脚型静电梳状硅微谐振器的谐振频率、弹性系数、横向最大位移会随两根支撑梁的间距变化而改变,并当此间距超过某一值后,上述三变量的变化均很小且趋向于一定值。同样,后者的谐振频率会随支撑梁厚度的变化而单调改变,这也是前者所没有的现象。为此从两者因为超静定次数不同而约束冗余度不同的角度,对此现象进行了物理意义上的解释。经与试验结果对比,单侧支撑直脚型静电梳状硅微谐振器横向谐振频率的理论值与实测值吻合较好,最大误差为12.07%。

关键词：微型机电系统静电硅微谐振器单侧支撑性能分析

交流电作用下电热致动器的热疲劳失效机理研究

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机械工程学报 2016年第18期52卷 77-84页

作者：王振禄沈雪瑾陈晓阳上海大学机械自动化工程系上海200072 兰州城市学院石油工程学院兰州730070

针对电热致动器在交流电作用下承受交变温度载荷而发生热疲劳失效的现象,分析热疲劳失效机理。建立电热致动器的瞬态温度分析模型和力学模型,实测致动位移,实测位移与理论计算、有限元仿真结果一致。温度和应力计算表明,结构形式和施加... 详细信息

针对电热致动器在交流电作用下承受交变温度载荷而发生热疲劳失效的现象,分析热疲劳失效机理。建立电热致动器的瞬态温度分析模型和力学模型,实测致动位移,实测位移与理论计算、有限元仿真结果一致。温度和应力计算表明,结构形式和施加的电压直接影响致动器的温度分布和应力大小,因最大应力小于屈服强度极限而不会发生应力引起的疲劳失效。测试交流电作用下致动位移和循环次数的关系,试验结果和理论计算表明,温度低于脆性-韧性转换温度,电热致动器不发生热疲劳失效,否则在长期循环后会发生热疲劳失效。300～600℃的温度对电热致动器的工作最有利,在此温度范围内能够精确稳定地提供数千万次的致动循环。根据失效现象,分析热疲劳失效机理,得出高温变形是引发热疲劳失效的直接原因,交流电压的幅值和频率对热疲劳的作用都能统一到温度上。

关键词：微机电系统电热致动器交变温度载荷热疲劳失效失效机理