Non-Newtonian effects on lubricant thin film flows

An analysis of non-Newtonian effects on lubrication flows is presented based on the upper-convected Maxwell constitutive equation, which is the simplest viscoelastic model having a constant viscosity and relaxation time. By employing characteristic lubricant relaxation times in all order of magnitude analysis, a perturbation method is developed to analyze the flow of a non-Newtonian lubricant between two surfaces. The effect of viscoelasticity on the lubricant velocity and pressure fields is examined, and the influence of minimum film thickness on lubrication characteristics is investigated. Numerical simulations show a significant enhancement in the pressure field when the minimum film thickness is sufficiently small. This mechanism suggests that viscoelasticity does indeed produce a beneficial effect on lubrication performance, which is consistent with experimental observations.

[1]  K. Walters,et al.  Computational rheology: a new science , 1993 .

[2]  Andras Z. Szeri,et al.  Some Extensions of the Lubrication Theory of Osborne Reynolds , 1987 .

[3]  Timothy Nigel Phillips,et al.  Three‐dimensional effects in dynamically loaded journal bearings , 1999 .

[4]  Chester K. Murphy,et al.  A Correlation Between Engine Oil Rheology and Oil Film Thickness in Engine Journal Bearings , 1986 .

[5]  Terence W. Bates,et al.  The viscoelastic properties of multigrade oils and their effect on journal-bearing characteristics , 1997 .

[6]  Lubricant elasticity and the performance of dynamically loaded short journal bearings , 1990 .

[7]  Andras Z. Szeri,et al.  Fluid Film Lubrication: Theory and Design , 1998 .

[8]  R. Craster,et al.  Surfactant spreading on a thin weakly viscoelastic film , 2002 .

[9]  A. R. Davies,et al.  Numerical modelling of pressure and temperature effects in viscoelastic flow between eccentrically rotating cylinders , 1994 .

[10]  A. Cameron Basic lubrication theory , 1976 .

[11]  R. Khayat Transient two-dimensional coating flow of a viscoelastic fluid film on a substrate of arbitrary shape , 2000 .

[12]  Robert C. Armstrong,et al.  Dynamics of polymeric liquids: Fluid mechanics , 1987 .

[13]  Peter Fischer Engineering Rheology - Second Edition , 2002 .

[14]  H. Barnes,et al.  An introduction to rheology , 1989 .

[15]  and D Dowson,et al.  Cavitation in Bearings , 1979 .

[16]  J. Tichy Non-Newtonian Lubrication With the Convected Maxwell Model , 1996 .

[17]  K. Walters,et al.  On viscoelastic effects in journal-bearing lubrication , 1992 .