1999 Fiscal Year Final Research Report Summary
Study on mechanical environments and tribo-failures at the operating surfaces of mechanical elements
| Project/Area Number |
09450071
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
設計工学・機械要素・トライボロジー
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
ICHIMARU Kazunori Kyushu University, Graduate School of Engineering, Professor, 工学研究科, 教授 (60037760)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Hiroyoshi Kyushu University, Graduate School of Engineering, Research Associate, 工学研究科, 助手 (80264076)
MORITA Takehiro Kyushu University, Graduate School of Engineering, Research Associate, 工学研究科, 助手 (70175636)
IZUMI Naoshi Kyushu University, Graduate School of Engineering, Associate Professor, 工学研究科, 助教授 (60184579)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Mixed lubrication / Surface roughness / Transient EHL / Direct contact / Rolling fatigue / Fretting wear / Contact stress / Contact of cylindrical bodies |
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| Research Abstract |
A numerical method of analysis for unsteady mixed elastohydrodynamic lubrication with direct contacts was developed. In order to make the analysis possible, three states of the contacting regions are distinguished, I.e., the hydrodynamic-film-formation, the direct contact and the cavitation regions, to which different equations are applied, respectively. in place of Reynolds equation applied to the hydrodynamic-film-formation region, elasticity equation is used as the governing equation of the direct-contact region. Not only pressure and film-thickness, but also the oil mass quantity at each point in the calculation region are always grasped and used to decided the state of the point and the governing equation. This numerical calculation method was applied to the cases where mixed elastohydrodynamic lubrication with direct contacts occurred.
Experimental study on false brinelling of ball bearings, which is identified as fretting wear caused by repeated microslip in raceways, has been conducted in oscillatory motion in order to investigate the effect of several operating conditions and lubrication on the service life. The state of oil-film formation was measured with the electric resistance method, and it was found that the life depends on the state of oil-film formation. The roughness of raceways can affect the state of oil-film formation and the life of ball bearings in oscillatory motion.
Experimental study on pitting has been conducted using two-roller machine. The surface of test rollers were recorded in video tape at every adequate loading cycles and evident pitting cracks observed after a long running were followed from an early state of running by reversing the time. The influences of the plastic flow direction and the rheological properties of lubricating oils were recognized significantly.
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