2005 Fiscal Year Final Research Report Summary
Prediction of High-Pressure Pheology of Lubricating Oils Based on Phase Diagram
| Project/Area Number |
16560122
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Design engineering/Machine functional elements/Tribology
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| Research Institution | Saga University |
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Principal Investigator |
OHNO Nobuyoshi Saga University, Faculty of Science and Engineering, Department of Mechanical Engineering, Professor, 理工学部, 教授 (00039265)
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| Project Period (FY) |
2004 – 2005
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| Keywords | tribology / lubricating oil / density / viscosity / phase diagram / free volume / EHL / DAC |
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| Research Abstract |
1.Application of Acoustic Emission for High-Pressure short Time Solidification of Traction Fluids
The lubricating oils solidify at quasi-static high-pressure as the amorphous or glassy solids are verified by a number of studies. However, solidification of lubricating oil under the dynamic condition as the rolling bearings and the traction CVT is not clear. The high-pressure short time solidification of traction fluids is examined by the analysis of dent after the impact tests and AE analysis under impact loads. The intensity of each impact collision is measured by means of an acoustic emission (AE) sensor. The dimensionless AE r.m.s value is investigated by based on phase diagram of testing oils. It was recognized the solidification of oil under the dynamic high-pressure condition almost corresponded to the static condition.
2.Bulk Modulus of Lubricating Oils as Predominant Factor Affecting Tractional Behavior in High-Pressure Elastohydrodynamic Contacts
The phase diagrams were first made
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up by high-pressure density measurements and others. The bulk modulus of lubricating oils was evaluated using a phase diagram. The bulk modulus is closely related to the oil molecular packing parameter T_<VE>-T (where T_<VE> is the viscoelastic solid transition temperature at pressure p, and T is the oil temperature). Next, the elastohydrodynamic lubrication traction was measured by a ball-on-disk machine. The results indicated that the maximum traction coefficient is closely related to T_<VE>-T. As a result, the importance of the bulk modulus as a predominant factor for traction characteristics lubricating oil was pointed out.
3.Anti-Wear Action by Solidified Oil Film in Sliding Concentrated Steel Contacts
The phase diagram of twenty-two kinds of oil was obtained through high-pressure density measurement. The four-ball were teats were used to evaluate the anti-wear characteristics of oils in boundary lubrication condition. The results indicated that the anti-wear action by fluid in sliding concentrated steel contacts is closely related to the oil molecular packing parameter T_<VE>-T and besides the effect of EHL the solidification oils rather has a predominating influence on actual anti-wear performances of boundary lubrication. It is confirmed that the solidified oil film under the boundary lubrication has the anti-wear action.
4.Measurement of the density of lubricating oils at pressures to 2.20 GPa using diamond anvil cell (DAC)
Using a DAC as pressure-generating device, the measurement of of density of drop of oil became possible. The density is calculated by measuring the volume change from the thickness of austenitic stainless steel gasket (thickness 0.5mm) and inner diameter of chamber (inner diameter 0.5mm, height 0.5mm). The density variation with the pressure of traction oil, lubricant for space applications and mineral oil is investigated for pressures up to 2.20GPa. The density variation for each lubricant is presented as a curve fit. The phase diagram of each lubricant is made. Less
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