The shear-thinning elastohydrodynamic film thickness of a two-component mixture

Yuchuan Liu, Q. Jane Wang, Ivan Krupka, Martin Hartl, Scott Bair*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Lubricant base oils are often blends of different molecular weight cuts to arrive at a specified ambient pressure viscosity and, to improve the temperature-viscosity behavior or to simply increase the viscosity, viscosity-modifying polymer additives are often added to the base oil. This paper investigates the effect of mixture rheology on elastohydrodynamic lubrication (EHL) film thickness using EHL contact measurements and a full numerical analysis for three synthetic lubricants including two single-component lubricants PAO650 and PAO100 and a mixture of these. The pressure and shear dependences of the viscosity of these lubricants were measured with high-pressure viscometers; viscosities were not adjusted to fit experiment. The point contact film thicknesses for these lubricants in pure rolling were measured using a thin-film colorimetric interferometry apparatus. Numerical simulations based on the measured rheology show very good agreement with the measurements of film thickness while the Newtonian prediction is up to twice the measurement. These results validate the use of realistic shear-thinning and pressure-viscosity models, which originate from viscosity measurements. It is conceivable that simulation may provide a means to "engineer" lubricants with the optimum balance of film thickness and friction through intelligent mixing of components.

Original languageEnglish (US)
Pages (from-to)1-7
Number of pages7
JournalJournal of Tribology
Issue number2
StatePublished - Apr 2008


  • EHL
  • Elastohydrodynamics
  • Film thickness
  • Non-Newtonian
  • Rheology
  • Shear thinning
  • Viscosity

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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