Tribology and Lubricants

Korean Tribology Society (한국트라이볼로지학회)
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Wear Analysis of Journal Bearings Operating in a Shaft During Motoring Start-up and Coast-down Cycles - Part II: Wear Analysis of two Journal Bearings Supporting a Misaligned Shaft

모터링 시동 및 시동정지 사이클에서 경사진 축을 갖는 저어널베어링의 마모 해석 - Part II: 경사진 축을 지지하는 두 저어널베어링의 마모해석

  • Chun, Sang Myung (School of Mechanical Engineering, Dept. of Automotive Engineering, Hoseo University)
  • 전상명 (호서대학교 기계공학부 자동차공학전공)
  • Received : 2017.06.19
  • Accepted : 2017.08.04
  • Published : 2017.08.31
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Abstract

This paper presents a wear analysis procedure for calculating the wear of journal bearings during the start-up and coast-down cycles of a motoring stripped-down single cylinder engine operating with a tilted shaft. In order to decide whether the lubrication state of a journal bearing is in the mixed-elasto-hydrodynamic lubrication regime, we utilize lift-off speed and MOFT (most oil film thickness) under mixed-elasto-hydrodynamic lubrication regime at the corresponding aligned shaft. We formulate an equation for the modified film thickness in a misaligned journal bearing considering the additional wear volume described in Part I of this study. For this, we use the calculation results of the degree of misalignment and tilting angle obtained after finding the eccentricities of the two bearings supporting the crankshaft of a single cylinder engine. In this Part II, we calculate the wear of journal bearings using the fractional film defect coefficient, the asperity load sharing factor, and the modified specific wear rate for the application of mixed-elasto-hydrodynamic lubrication regime. We show that the accumulated wear volume after turning the ignition switch on and off once, increases to ${\sigma}=39{\mu}m$ and then decreases from ${\sigma}=39{\mu}m$ with increasing in surface roughness.

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References

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