On the concentrated contact as a viscometer

Abstract

Lubricant viscosities from published concentrated contact-based measurements are compared with measurements by conventional viscometry for overlapping pressures and viscosities. Contrary to published claims there are important differences. The greater than exponential pressure-viscosity behaviour, which is known to occur at high pressures, is absent from contact measurements. Deficiencies in contact-based techniques are probably due to assumed constitutive behaviour and are not related to time scale. In general, contact-based methods are poorly conditioned for the measurement of pressure-viscosity coefficients.

Keywords

elastohydrodynamic lubrication viscosity pressure traction film thickness

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References

Bair

The pressure-viscosity coefficient at Hertz pressure and its relation to concentrated contact traction.

In Proceedings of the 26th Leeds-Lyon Symposium on Tribology, 1999, pp. 433–443.

Bridgman

P. W.

The Physics of High Pressure, 1931, pp. 330–340 (Dover Publications, New York).

Bridgman

P. W.

The viscosity of liquids under pressure

Proc. Natn. Acad. Sci. USA, 1926, 11, 603–606.

Bridgman

P. W.

Viscosities to 30,000 kg/cm² especially certain liquids. Proc. Am. Acad. Arts Sci., 1949, 77, 117–128.

Bondi

Physical Properties of Molecular Crystals, Liquids and Glasses, 1968, p. 355 (John Wiley, New York).

King

H. E.

Cook

R. L.

Herbst

C. A.

Density scaling of viscosity measured via diamond cell viscometry In High Pressure Science and Technology, 1994, pp. 1055–1058 (American Institute of Physics, New York).

Sutcliffe

M. P. F.

Measurements of the rheological properties of a kerosene metal-rolling lubricant

Proc. Instn Mech. Engrs, Part B, Journal of Engineering Manufacture, 1991, 205 (B3), 215–219.

Evans

C. R.

Johnson

K. L.

Regimes of traction in elastohydrodynamic lubrication

Proc. Instn Mech. Engrs, Part C, Journal of Mechanical Engineering Science, 1986, 200 (C5), 313–324.

Moore

A. J.

The behaviour of lubricants in elastohydrodynamic contacts

Proc. Instn Mech. Engrs, Part J, Journal of Engineering Tribology, 1997, 211 (J2), 91–106.

10.

Muraki

Dong

Derivation of basic rheological parameters from experimental traction curves

Proc. Instn Mech. Engrs, Part J, Journal of Engineering Tribology, 1999, 213 (J1), 53–61.

11.

Bair

Pressure-viscosity behavior of lubricants to 1.4 GPa and its relation to EHD traction. STLE paper 99-TC-9, 1999, p. 5.

12.

Yokoyama

Spikes

Film-forming properties of polyol ester, polyphenyl ethers and their mixtures over a wide range of temperature. STLE paper 99-TC07, 1999, p. 2.

13.

LaFountain

A. R.

The behaviour of lubricant blends in elastohydrodynamic contacts. Thesis, Imperial College, London, 1999, p. 128.

14.

Bair

Recent developments in high-pressure rheology of lubricants In Lubricants and Lubrication, 1995, p. 172 (Elsevier, Amsterdam).

15.

Jones

W. R.

Properties of perfluoropolyethers for space applications

STLE Tribology Trans., 1995, 38 (3), 560.