On the concentrated contact as a viscometer

Bair, Scott

doi:10.1243/1350650001543386

Cited by 7 publications

(3 citation statements)

References 12 publications

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“…Several models exist but there is still active debate about which, if any, are appropriate to the extreme conditions present between asperities. 31 Until very recently, all of the above rough-surface EHDtype modelling considered only relatively thick, micro-EHD conditions and did not examine very thin-film contacts where there was the possibility of zero EHD film between asperities, i.e., of true mixed lubrication. Recently, however, Hu and Zhu~2,.…”

Section: Modelling Of Thinfilm Mixed Contactmentioning

confidence: 99%

Basics of mixed lubrication

Spikes

Olver

2003

Lubrication Science

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This paper reviews recent research in mixed lubrication, focusing on the current understanding of lubricant entrainment, and thus film thickness, and of friction in thin‐film, rough‐surface lubricated contacts. By combining research using optical interferometry on the experimental side and numerical modelling on the theoretical side, we now have a reasonable understanding of micro‐elastohydrodynamic lubrication, although design rules are still lacking. The regime of true mixed lubrication, where there are both elastohydrodynamic and boundary lubricated regions within a single contact, remains quite poorly understood. New experimental techniques as well as new information about very thin‐film rheology under high‐strain and high‐pressure conditions are probably needed before much further progress can be made in this area.

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Section: Modelling Of Thinfilm Mixed Contactmentioning

confidence: 99%

Basics of mixed lubrication

Spikes

Olver

2003

Lubrication Science

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“…[4] for octane from the data of the two laboratories. The minimum pressure interval, pl, was varied from I2 to 49 MPa.…”

Section: Example Calculations Of A* and A For Octanementioning

confidence: 99%

Accurate Measurements of Pressure-Viscosity Behavior in Lubricants

Bair

Qureshi²

2002

Tribology Transactions

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T11e l~iezoviscous eflect is accurately characterized for a numher of rel)rr.setrtative Irthricating oil base stocks and a siniple, well-(l~fitrerl Iryrlrocurhori. Proceduws for the generation of accurute presstr,r-~~i.scosity coefficients are outlined. Tlie reciprocal cr.sytirptotic iso~~iscous pressure niay he measured to u~irhin per11rt11.s 1%. Tlre piezovi.scous effect niay he important to automotive jirel ecotroniy. Tlie depart~cre from exporzential behavior at very l o~l ~~~S S I I I Z ' hecon~es nrore prvrloutzced at high temperature.

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“…Viscometers have been in use for many years and are most appropriate to determine the pressure-viscosity coefficient of lubricants, see Bair [4]. Only a few institutes have a high-pressure viscometer, while many have film thickness measurement devices.…”

Section: Introductionmentioning

confidence: 99%

The determination of the pressure—viscosity coefficient of a lubricant through an accurate film thickness formula and accurate film thickness measurements

Leeuwen

2009

Proceedings of the Institution of Mechanical Engineers, Part J:

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The pressure-viscosity coefficient is an indispensable property in the elastohydrodynamic (EHD) lubrication of hard contacts, but often not known. A guess will easily lead to enormous errors in the film thickness. This article describes a method to deduct this coefficient by adapting the value of the pressure-viscosity coefficient until the differences between accurate film thickness approximation values and accurate film thickness measurements over a wide range of values are at a minimum. Eleven film thickness approximation formulas are compared in describing the film thickness of a test fluid with known value of the pressure-viscosity coefficient. The measurement method is based on spacer layer interferometry. It is concluded that for circular contacts the newer more versatile expressions are not better than some older approximations, which are limited to a smaller region of conditions, and that the older fits are as least as appropriate to find the pressure-viscosity coefficient of fluids, in spite of the limited data where they have been based on.

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On the concentrated contact as a viscometer

Cited by 7 publications

References 12 publications

Basics of mixed lubrication

Basics of mixed lubrication

Accurate Measurements of Pressure-Viscosity Behavior in Lubricants

The determination of the pressure—viscosity coefficient of a lubricant through an accurate film thickness formula and accurate film thickness measurements

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