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In this paper we examine the question of whether the viscoelastic properties of multigrade oils can have a measurable effect on the performance of dynamically loaded journal bearings. Our investigation takes the form of a computational study in which the full set of coupled equations (kinematic and constitutive) governing the flow of the lubricant is solved using a moving spectral element method. The lubricant is modelled using the White-Metzner constitutive relationship.

The performance of journal bearings is dependent on many factors such as design, materials, load cycle and lubricant. The behaviour of lubricants in automotive bearings is of critical importance as the size of the bearing is restricted due to engine compartment space constraints and the loadings are increased with rising power output. The traditional approach to the modelling of journal bearing lubrication has been via the “lubrication approximation” introduced by Reynolds. If the lubrication approximation is not invoked, then there is no option but to solve the full set of coupled equations (kinematic and constitutive) governing the flow of the lubricant and taking proper account of the moving parts of the geometry. Until recently, this task has proved too formidable, but with current computing power, combined with efficient and accurate numerical methods, the calculation may be attempted.