| Project/Area Number |
01550119
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
機械要素
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| Research Institution | Kyushu University |
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Principal Investigator |
YAMAMOTO Yuji Kyushu Univ., Fac. Eng., Prof., 工学部, 教授 (10037997)
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| Co-Investigator(Kenkyū-buntansha) |
GONDO Seigo Kyushu Univ., Fac. Eng., Assist., 工学部, 助手 (50037975)
SUGIMURA Joichi Kyushu Univ., Fac. Eng., Assoc. Prof., 工学部, 助教授 (20187660)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1990: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1989: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Tribology / EHL / Lubricant / Solidification / Critical shear stress / Glass transition / 弾性流体潤滑 / トラクション / 粘弾性 / 弾塑性 |
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| Research Abstract |
Lubricants behaved as elastic-plastic solid at temperatures below their glass transition temperatures in shear ring tests carried out with a concentric double cylinder apparatus. In the temperature range a lubricant were sheared only within a narrow shear band in the vicinity of the inner cylinder surface. There was a critical shear stress, of which the magnitude decreased with the sliding velocity. A lubricant with high traction coefficient in two disc machine testing had a large critical shear stress.
In four ball testing, the lubricant with the lowest solidification pressure made the thickest oil film. Once a thick solidifies film was formed under a condition of high sliding velocity, the thick film was retained and had an ability to prevent the rubbing surfaces from direct contact even when the sliding velocity was decreased.
Under rolling/sliding contact conditions, in contrast to viscous fluid the traction coefficient decreased with an increase in the shear rate or the sliding velocity in cases where the lubricant behaved as a elastic-plastic solid. The traction coefficient of the elastic-plastic solid could be practically determined only by the value of ap, where a is the viscosity-pressure coefficient of the lubricant and p the mean contact pressure. The ap seems to be a measure of the packing state of the lubricant molecules in the contact region.
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