• KSTLE International Journal
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• 제2권2호
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• pp.103-113
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• 2001

The influence of aerated oil on high-speed journal bearing is examined by classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing. Convection to the walls and mixing with supply oil and re-circulating oil are considered. The live oil surface tension is considered as functions of temperature, API gravity and air volume ratio. With changing eccentricity ratio, it is investigated the effects of air bubbles on the performance of a high-speed plain journal bearing. Just at the moderate eccentricity ratios, even if the involved aeration levels are not so severe and the entrained air bubble sizes are not so small, it is found that the bearing load and friction farce may be changed so visibly for the high speed bearing operation.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.111-112
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• 2002

The influence of aerated oil on a high-speed proceeding bearing is examined by using the classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing including the live surface tension of aerated oil. Convection to the walls and mixing with supply oil and re-circulating oil are considered. The considered parameters for the study of bubbly lubrication are oil aeration level, air bubble size and shaft speed. The results show that, if the live surface tension is considered, the effect of air bubbles on the bearing load capacity is reduced due to temperature engagement comparing with that under the condition of a constant surface tension.

• 한국자동차공학회논문집
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• 제16권3호
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• pp.137-143
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• 2008

For most bearings, it is a common requirement to have long durability. Especially wheel bearing fatigue life is the most important in automotive quality. The contact fatigue life analysis of automotive wheel bearing considering real raceway rough surface is presented in this paper. Contact stresses are obtained by contact analysis of a semi-infinite solid based on the use of influence functions; the subsurface stress field is obtained using rectangular patch solutions. Mesoscopic multiaxial fatigue criterion which can yield satisfactory results for non-proportional loading is then applied to predict fatigue damage. Suitable counting method and damage rule were used to calculate the fatigue life of random loading caused by rough surface. The life analysis considering real rough surface of wheel bearing raceway is in good agreement with the experimental results.

• 대한기계학회논문집A
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• 제25권4호
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• pp.725-733
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• 2001

Flying attitudes of the slider, which are flying height, pitch and roll, are affected by the air flow velocity, the skew angle, and the manufacturing tolerances. Traditional designs of the air bearing surface have considered only the flying performances for the variations in the air flow velocity and the skew angle, which are determined by the radial position. In this study, we present the new shape design of the air bearing surface by considering the track seek performance and the air bearing stiffness as well as the traditional design requirements. The optimization technique is used to improve the dynamic characteristics and operating performance of the newly proposed air bearing surface shape design further. The optimized configuration is obtained automatically and the optimally designed sliders show the enhanced flying and dynamic characteristics.

• Tribology and Lubricants
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• 제14권1호
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• pp.7-13
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• 1998

The static characteristics of a five-pad tilting pad journal bearing of load on pad (LOP) type have been investigated experimentally under the different values of bearing load and shaft speed. The diameter and length of the bearing are 300.91 mrn and 149.8 mm, reslx;ctively. Circumferential distribution of the film pressure, film thickness, journal surface temperature and beating surface temperature are measured. A noticeable inlet pressure rise is observed at the entrance of each pad, especially the bottom pad. The inlet pressure is increased by the increase of shaft speed as well as bearing load. In the five-pad tilting pad joumal bearing of LOP type, almost all of beating load is being carried only by the bottom pad. The maximum bearing surface temperature is observed at near the minimum film thickness. It is observed that the metal temperature of the mid-plane is higher than that of the edge at the inlet region, while the metal temperature of the edge is higher than that of the mid-plane at the outlet region.

• 대한족부족관절학회지
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• 제15권3호
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• pp.159-164
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• 2011

Purpose: This study was performed to analyze the results of radiologic parameters between weight bearing affected single ankle anteroposterior (AP) view and both ankle AP view in ankle osteoarthritis (OA). Materials and Methods: Between January 2009 and August 2010, 41 patients (50 ankles) who visited our institution to treat ankle OA were reviewed retrospectively. In radiographic assessment, weight bearing affected single ankle AP view and both ankle AP view were checked, and measured tibial anterior surface angle (TAS), tibial medial malleolar angle (TMM), talar tilting angle (TT), maximum and minimun joint space width (JSW) of ankle, width between articular surface of medial malleolar and medial articular surface of talus as radiologic parameters. Results: On weight bearing both ankle AP view, TAS was $85.4{\pm}4.1^{\circ}$, TMM was $33.1{\pm}9^{\circ}$, TT was $5.4{\pm}6.1^{\circ}$, maximum JSW was $3.2{\pm}2.7$ mm, minimum JSW was $1.1{\pm}1.3$ mm, width between articular surface of medial malleolar and medial articular surface of talus was $1.8{\pm}1.8$ mm and on weight bearing affected ankle AP view, TAS was $85.3{\pm}3.9^{\circ}$, TMM was $34.3{\pm}10.9^{\circ}$, TT was $5.4{\pm}6.5^{\circ}$, maximum JSW was $3.2{\pm}2.7$ mm, minimum JSW was $1.1{\pm}1.3$ mm, width between articular surface of medial malleolar and medial articular surface of talus was $1.6{\pm}1.7$ mm. Conclusion: There is no statistical significance in radiologic parameters between weight-bearing affected single ankle AP view and both ankle AP view in ankle OA.

• 한국표면공학회지
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• 제18권1호
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• pp.12-19
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• 1985

• 한국유체기계학회 논문집
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• 제12권6호
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• pp.33-40
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• 2009

The temperature of vertical pump bearing metal in the pumped storage power plant has been high enough to shutdown the unit. Attempts such as decreasing the oil supply temperature, increasing the bearing oil gap etc. were performed to resolve the problem, but the issue was not resolved. Finally, the high bearing metal temperature was corrected by adjusting the bearing preload. The preload is formed by the oil wedge between the journal surface and bearing pad surface and the degree of preload is determined by the machined radial clearance, assembled radial clearance, rotor journal diameter etc. This paper focuses on the analysis of the preload depending on the bearing parameters and the result of the modification of the bearing following the analysis. The bearing metal temperature dropped as much as $20^{\circ}C$ which was similar as expected by software calculation. But the shaft vibration could increase when the assembled radial clearance is excessive. So, the adjustment of the bearing preload for the tilting pad type journal bearing should be carefully performed.

• 한국생산제조학회지
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• 제21권5호
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• pp.741-746
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• 2012

The increase of energetic efficiency in plane bearing is getting more important in the transfer mechanism of semi-conductor and display panel manufacturing processes. To accomplish this objective, the technique of surface texturing on bearing surface has recently emerged as one of the most effective candidates. In this study, the effects of various pattern parameters on two bearing performance indices(load carrying capacity and effective friction coefficient) are investigated through a semi-analytic method, i.e., the 2-dimensional Reynolds equation incorporated into the finite difference scheme. Here, cavitation effect is also taken into account by employing an appropriate numerical scheme. In this study, the patterns in the textured surface are composed of a series of semi-spheres or semi-ellipsoids in shape. The effects of their size and number density on the performance indices are examined through the performance of various numerical experiments. Also, the effects of the anisotropy of the semi-ellipsoidal pattern on the bearing's lubrication characteristics are investigated and discussed.

• Journal of Magnetics
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• 제5권2호
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• pp.55-58
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• 2000

Local magnetic properties and magnetization distributions on the air-bearing surface of a thin-film magnetic head have been studied by using scanning magneto-optical Kerr microscopy. The examined head was a merged MR read/inductive writing head with a write gap equal to 0.3 $\mu m$. Sizes of top and bottom pole-tips on the air-bearing surface of the writing head were equal to $3\mu m\times3\mu m$ and $3\mu m\times30\mu m$, respectively, The measured magnetic characteristics on the head air-bearing surface were found to be very sensitive to the head design. In particular, magnetization distributions were discovered to have asymmetrical shape. Maximum magnitudes of the magnetization were located near the shorten pole-tip. So, it was experimentally proved that more magnetic flux emanates just from this part of the air-bearing head surface.