Molecular structure of synthetic hydrocarbon oils and their rheological properties governing traction characteristics

Muraki, Masayoshi

doi:10.1016/0301-679x(87)90063-6

Cited by 51 publications

(27 citation statements)

References 10 publications

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“…Much systematic research to relate EHD friction to molecular structure has been driven by the design of traction fluids which requires high EHD friction [4][5][6][7][8][9][10][11]. In an important study in 1970, Hammann et al [4] demonstrated that molecules with one, and especially with two cyclohexyl rings, gave high EHD friction.…”

Section: Previous Workmentioning

confidence: 99%

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Effect of Base Oil Structure on Elastohydrodynamic Friction

2016

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The EHD friction properties of a wide range of base fluids have been measured and compared in mixed sliding-rolling conditions at three temperatures and two pressures. The use of tungsten carbide ball and disc specimens enabled high mean contact pressures of 1.5 and 2.0 GPa to be obtained, comparable to those present in many rolling bearings. The measurements confirm the importance of molecular structure of the base fluid in determining EHD friction. Liquids having linear-shaped molecules with flexible bonds give considerably lower friction than liquids based on molecules with bulky side groups or rings. EHD friction also increases with viscosity for liquids having similar molecular structures. Using pure ester fluids, it is shown that quite small differences in molecular structure can have considerable effects on EHD friction. The importance of temperature rise in reducing EHD friction at slide-roll ratios above about 5% has been shown. By measuring EHD friction at several temperatures and pressures as well as EHD film thickness, approximate corrections to measured EHD friction data have been made to obtain isothermal shear stress and thus EHD friction curves. These show that under the conditions tested most low molecular weight base fluids do not reach a limiting friction coefficient and thus shear stress. However, two high traction base fluids appear to reach limiting values, while three linear polymeric base fluids may also do so. Constants of best fit to a linear/logarithmic isothermal shear stress/strain rate relationship have been provided to enable reconstruction of isothermal EHD friction behaviour for most of the fluids tested.

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Section: Previous Workmentioning

confidence: 99%

“…Muraki [6] studied both ring and branched chain structures and found that for the latter EHD friction increased with the degree of branching. He analysed friction data using a viscoelastic Eyring model and noted that the Eyring stress decreased with degree of branching and also with molecular volume.…”

Section: Previous Workmentioning

confidence: 99%

Effect of Base Oil Structure on Elastohydrodynamic Friction

2016

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“…Muraki derived a theoretical formula for the maximum traction coefficient using thermal analysis based on the nonlinear Maxwell model. As a result of applying the above formula for the range of 293 to 393 K, µ max decreases almost linearly with increasing temperature (12) . Kato obtained µ max at more than 313 K based on µ max of 313 K. In this case, µ max decreases almost linearly with increasing temperature (13) .…”

Section: Influence Of Film Thickness On Traction Coefficientmentioning

confidence: 92%

“…δ is obtained by substituting the estimated film thicknesses of grease A and grease B into Eq. (12). The estimation formula for the µ max of traction grease considering the difference in film thickness between traction oil and grease is obtained by substituting δ into Eq.…”

Section: Property Change From Traction Oil To Traction Greasementioning

confidence: 99%

Evaluation of Property Difference between Traction Oil and Traction Grease

Yamanaka

Kumagai

Inoue

et al. 2009

JAMDSM

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In this paper, the characteristics of traction grease are evaluated. The difference in film formation ability between traction oil and traction grease is focused on, and the state of film formation and the traction coefficient of traction oil and two types of traction grease with different consistencies are measured simultaneously while varying temperature, Hertzian pressure and rolling speed. The traction coefficient of traction grease at a low temperature, a low pressure and a high peripheral speed shows a value larger than that of traction oil. The film thickness of traction grease is measured by the contact ratio method and decreases markedly at a low temperature and a high peripheral speed compared with that of traction oil. An estimation formula for traction grease considering film thickness is developed. These results lead to the conclusion that the property change between traction oil and traction grease is caused by the change of the film formation state.

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“…Values of r,, obtained from traction tests using (14) are typically less than 6 MPa [36,38] for cycloaliphatic traction fluids under conditions of Figure 14. Clearly, from Figure 14, the Newtonian limit exceeds 6 MPa and is close to 25 MPa.…”

mentioning

confidence: 99%

Deformation Behavior of Thin Lubricant Films at Elevated Pressure.

Bair¹

1994

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Molecular structure of synthetic hydrocarbon oils and their rheological properties governing traction characteristics

Cited by 51 publications

References 10 publications

Effect of Base Oil Structure on Elastohydrodynamic Friction

Effect of Base Oil Structure on Elastohydrodynamic Friction

Evaluation of Property Difference between Traction Oil and Traction Grease

Deformation Behavior of Thin Lubricant Films at Elevated Pressure.

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