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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Tribologists and Lubrication Engineers
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Journal DOI :
The Korean Society of Tribologists and Lubrication Engineers
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Volume & Issues
Volume 17, Issue 6 - Dec 2001
Volume 17, Issue 5 - Oct 2001
Volume 17, Issue 4 - Aug 2001
Volume 17, Issue 3 - Jun 2001
Volume 17, Issue 2 - Apr 2001
Volume 17, Issue 1 - Feb 2001
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Lubricating Mechanism Analyzed from Wear Characteristics of Polyolester Base Oils Haying different Branch Shapes(II)
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 17, issue 3, 2001, Pages 171~178
In order to elucidate the lubricating mechanism of polyolester base oils [POEs], the wear characteristics of 27 kinds of polyolester base oils including mixed POEs were investigated. Their wear results were discussed in terms of the effect of molecular structure on wear performance and compared with those of mineral oil. In addition, the adsorption ability of POEs to reduced iron and their hydrolysis rates were measured and the effect of their molecular structures on the adsorptivity and hydrolysis rate of POEs was discussed, respectively. Finally, the lubricating mechanism anlyzed from these results of wear characteristics, adsorptivity and hydrolysis rate was proposed. That is to say, POEs are firstly adsorbed to friction surface and decomposed by hydrolysis or thermal degradation. Fatty acids obtained by degradation of POEs form adsorption film on friction surface. The larger become cohesive ability among fatty acid molecules in the adsorption film, the better gets the wear performance of POEs.
An Improvement of the Stability of Plane Journal Bearing using Leaf Spring Damper
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 17, issue 3, 2001, Pages 179~184
In order to improve the instability of plane journal bearing, it is introduced the leaf spring damper(LSD). The effects of dynamic characteristics of LSD on the stability of a plane Journal bearing were investigated theoretically. The improvements on the stability of a plane journal bearing with LSD are compared with the results of a floating ring journal bearing and of journal bearing without LSD. It found that a plane journal bearing with LSD will be an effective way in the improvement on the stability of rotor system.
An Experimental Study on Improvement of the Stability of Plane Journal Bearing using Leaf Spring Damper
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 17, issue 3, 2001, Pages 185~190
The purpose of present paper is to prove an improvement on stability of plane journal bearing due to the leaf spring damper (LSD) experimentally. A flexible rotor system is designed and manufactured, in order to generate oil whip instability of journal bearing at relative lower rotating speed. Vibration amplitude and instability onset speeds are investigated for a conventional plane journal bearing and plane journal bearing with LSD. To investigate the damping effects of LSD on stability of bearing, experiments are also conducted on the leaf spring dampers with and without working oil. It is found that the leaf spring damper can considerably increase the instability onset speed of a plane Journal bearing.
A study on the Nano adhesion and Friction at Different Contact Conditions using SPM
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 17, issue 3, 2001, Pages 191~197
Nano adhesion and friction characteristics between SPM(scanning electron microscope) tips and flat plates of different materials were experimentally studied. Tests were performed to measure adhesion and friction in AFM(atomic force microscope) and LFM(lateral force microscope) modes in different conditions of relative humidity. Three different Si
tips (rdaii : 15nm, 22nm and 50 nm) and three different flat plates of Si-wafer(100), W-DLC(tungsten-incorporated diamond-like carbon) and DLC were used. Results generally showed that adhesion and friction increased with the tip radius, and W-DLC and DLC surfaces were superior to Si-wafer. But the adhesion force of Si-wafer showed non linearity with the tip radius while W-DLC and DLC surfaces showed good correlation to the “JKR model”. It was found that high adhesion force between Si-wafer and a large radius of tip was caused by a capillary action due to the condensed water.
A Study on Effects of Oil Aeration Level on Engine Lubrication System by using Computer Program
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 17, issue 3, 2001, Pages 198~208
A Parametric study based on a computer analysis of the lubrication system of a four-cylinder gasoline engine is illustrated. Through the parametric study, the effects of various aeration levels on the change of oil flow rate and pressure are investigated. Also, at high oil temperature and low engine speed, the effect of oil aeration level on oil flow characteristics in lubrication system is investigated. The illustrated results may give to designers the guide lines of oil aeration level for the safe design of engine lubrication systems in terms of minimum pressure at crank oil bore.
Analysis of Rolling Contact Fatigue of Ball Bearing with Various Hardness by X-ray Diffraction
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 17, issue 3, 2001, Pages 209~215
In view of the effects of the hardness of material on fatigue, rolling contact fatigue process in hard metals seems to differ from it in soft metals. This paper has been aimed to compare the rolling contact fatigue process according to the hardness of materials. Rolling contact fatigue tests using the ball bearings assembled with the inner race of four different hardness have been carried out. In addition, residual stress and half-value breadth on/below the inner raceway during individual rolling contact fatigue have been measured by X-ray diffraction. The results of this study showed that the change of residual stress and half-value breadth during the rolling contact fatigue on race way in hard metals is the same as in soft metals. However, plastic deformation by rolling contact in hard metals is in microscopic scale but only for soft metals in macroscopic scale.
An Optimal Design of an ER-SFD Supporting a Rigid Rotor System
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 17, issue 3, 2001, Pages 216~220
This paper presents a parametric study and an optimal design of the ER-SFD supporting a rigid rotor system. An attempt is made to obtain the optimal design of an ER-SFD for a two degree-of-freedom rotor model. Such a simple model is used in order to get a better insight into the physics of the problem. A maximum whirl amplitude, supply pressure and voltage are considered, and a maximum whirl amplitude is minimized over a range of speeds and presented f3r some values of unbalance mass. The results presented in this paper provide important design information necessary to reduce a whirl amplitude of an ER-SFD.
An Experimental Study on the Effect of Wear Particles on the Sliding Behavior of Silver-Coated Bearing Steels
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 17, issue 3, 2001, Pages 221~227
The effect of silver particles on the sliding behavior of bearing steels was studied experimentally by using a ball-on-disk tribometer. Tests were performed in ambient air, dry air and vacuum. Disks of AISI 52100 were silver-coated by a thermal evaporation method, and the effects of silver particle transfer on friction were analyzed. In order to understand further the mechanism of silver particle transfer and its effect on friction and wear, pre-compressed silver particles were artificially introduced into the friction interface and the results were compared to those of silver-coated specimens. Results showed that the introduced silver particles produced transfer layers and resulted in low friction. It also showed that this low friction is closely related to the characteristic behavior of transfer layers. Shakedown occurred at the friction interface affected the friction and wear.
EHL Analysis of Connecting Rod Bearings Considering Effects of Temperature Variation
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 17, issue 3, 2001, Pages 228~235
EHL analysis of connecting rod bearing is proposed which includes effects of temperature variation in lubrication film. Lubrication film temperature is treated as a time-dependent, two-dimensional variable which is averaged over the film thickness, while connecting rod big end temperature is assumed to be time-independent and three-dimensional. It is assumed that a portion of the heat generated by viscous dissipation in the lubrication film is absorbed by the film itself, and the remainder flows into the bearing surface. Mass-conserving cavitation algorithm is applied and the effect of variable viscosity is included to solve the Reynolds equation. Simulation results of the connecting rod bearing in internal combustion engine are presented. It is shown that the temperature variation has remarkable effects on the bearing performance. It is concluded that the EHL analysis considering effects of the temperature variation is strongly recommended to predict the connecting rod bearing performance in internal combustion engine.
Effects of Kurtosis on the Flow Factors Using Average Flow Model
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 17, issue 3, 2001, Pages 236~243
In this study, flow factors are evaluated in terms of kurtosis using random rough surface generated numerically. As h/
become large ø
fp/, approach to 1 and ø
fs/ to 0 asymptotically regardless of kurtosis. ø
fp/ increase with increasing kurtosis in the mixed lubrication regime. ø
fs/ is associated with an additional flow transport due to the combined effect of sliding and roughness. As h/
fs/ increase up to a certain point, and then decrease toward zero. This behavior can be attributed to the increasing number of contacts in the mixed lubrication regime. ø
x/ in the presence of elastic deformation on the surface is larger than ø
x/ in the absence of it because local film thickness(h
T/) increases by elastic deformation.
Development of Diagnostic Expert System for Rotating Machinery with Journal Bearing
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 17, issue 3, 2001, Pages 244~250
A rotating axis diagnostic system supported with journal bearing has been established that has been widely used in the industry. In order to measure the most sensitive signals that would be generated in the abnormal operation, sensors which measure AE(acoustic emission), gap and acceleration have been attached at the various location on the experimental apparatus. Data were obtained in the steady state operational condition of the system which was verified through the empirical measurement. Notable discrepancies were observed in RMS acceleration signal which could be utilized to predict the undesirable operational condition of the system.