A simple iterative method is used for the computation of the central film thickness in a fully flooded elastohydrodynamic (EHD) point contact lubricated with a polymeric viscosity index (V1)-improved base oil. The shear stress dependence of the Vl-improved base oil is included in the iterative method. Experimental data are presented on temporary viscosity loss and central film thickness at different temperatures from —8 to 40° C.
A good approximation of the central film thickness in an EHD point contact lubricated with V1-improved oil is given by using an iterative method involving the temporary viscosity loss of the Vl-improved base oil. The central film thickness depends on the mean shear stress at the inlet of the contact, and this shear-thinning effect has been accounted for in the calculations.
WardleR. M. W.CoyR. C.CannP. H.SpikesH. A.An ‘in lubro’ study of viscosity index improvers in EHD contacts. Lubric. Sci., 1990, 3(1), 45–62.
7.
BartzW. J.About the influence of viscosity index improvers on the cold flow properties of engine oils. Tribology Int., February 1976, 13–19.
8.
BartzW. J.Investigation on the rheological behaviour of multigrade engine oils. CEW, 1989, 24(3), 67–75.
9.
von PeteryC.KruseH.BartzW. J.Influence of the viscosity of polymer containing engine oils on the startability of engines. SAE paper SP-78/429, 1978, pp. 15–23.
10.
HorowitzH. H.Predicting effects of temperature and shear rate on viscosity of viscosity index-improved lubricants. J. Ind. Engng Chem., 1958, 50, 1089–1094.
11.
HamiltonG. M.BottomleyL.Measurement of viscosity loss of polymer-containing oils at high shear stresses. Tribology Int., 1987, 20(1), 41–48.
12.
WalkerD. L.SanbornD. M.WinerW. O.Molecular degradation of lubricants in sliding elastohydrodynamic contacts. J. Lubric. Technol., 1975, 97, 390–397.
13.
BairS.WinerW. O.Shear rheological characterization of motor oils. STLE Tribology Trans., 1988, 31(3), 316–323.
14.
HirataM.CameronA.The use of optical elastohydrodynamics to investigate viscosity loss in polymer-thickened oils. ASLE Trans., 1984, 27(2), 114–121.
15.
HamrockB. J.DowsonD.The elastohydrodynamics of elliptical contacts, 1981, John Wiley, Chichester).
16.
DrazinP.ReidW.Hydrodynamic stability, 1981, Cambridge University Press).
17.
NicolasD.FreneJ.Study of diluted polymer solution in Couette flow with small gaps: visualization and torque measurements. Second Leeds-Lyon Symposium, 1975.
18.
GruntfestI. J.Apparent departures from Newtonian behavior in liquids caused by viscous heating. Trans. Soc. Rheol., 1965, 9(1), 425–441.
19.
SukanekR. C.LaurenceR. L.An experimental investigation of viscous heating in some simple shear flows. Ass. Ind. Chem. Engrs J., 1974, 20(3), 474–484.
20.
BairS.WinerW. O.The high shear stress rheology of liquid lubricants at pressures of 2 to 200 MPa. Trans. ASME, J. Tribology, 1990, 112, 246–253.
21.
CameronA.GoharR.Theoretical and experimental studies of the oil film in lubricated point contact. Proc. R. Soc., 1966, A291, 520–536.
22.
FoordC. A.HammannW. C.CameronA.Evaluation of lubricants using optical elastohydrodynamics. ASLE Trans., 1968, 11, 31–43.
23.
PoulterC.RitcheyC.BenzC. A.The effect of pressure on the index of refraction of paraffin oil and glycerine. Physical Rev., 1 August 1932, 41, 366–367.
24.
DowsonD.HigginsonG.Elastohydrodynamic lubrication; the fundamentals of roller and gear lubrication, 1966, Pergamon Press, Oxford).
