Analysis of non-Newtonian and piezoviscous effects in dynamically loaded connecting-rod bearings

Abstract

The dynamic behaviour of three elastic connecting-rod big-end bearings is studied. Non-Newtonian and piezoviscous behaviour of the lubricant is included. The present algorithm allows accurate analysis of film rupture and reformation during actual operation of an engine and is based on finite element discretization. The non-Newtonian effect is introduced by modifying the viscosity for each point of a three-dimensional mesh of the film and for each iteration. Using a convenient iterative solution procedure, converged solutions for lubricant flow and elastic deformation fields are obtained. The present algorithm is extended to a global thermo-elastohydrodynamic model, to take into account the effects of viscosity variation with temperature. It is shown that the non-Newtonian shear-thinning and oil piezoviscous effects cannot be neglected in a complete connecting-rod bearing analysis. Furthermore, thermo-elastic behaviour can lead to different conclusions, than obtained by the elastohydrodynamic model.

Effects of surface texturing in steady-state and transient flow conditions: Two-dimensional numerical simulation using a mass-conserving cavitation model

“…This particular form of the Reynolds equation was first introduced by Bonneau and Hajjam 26 in the early 2000s, when it was applied for the study of elastohydrodynamic effects in lubricated contacts, and later used by Fatu et al. 27–29 for the study of dynamically loaded bearings. The formulation is applied in both the active and the non-active regions of the lubricant film, with the universal function D and the cavitation size F satisfying the following conditions: where the cavitation pressure p cav is considered constant throughout the cavitation zone.…”

Computing hydrodynamic pressure in mixed lubrication by modified Reynolds equation

“…From equation (19), it is understood that p 0 does not depend on and . Using this fact and averaging equation ( 20) on L yields…”

“…The model used to predict the main journal bearing hydrodynamic parameters has been fully described by the authors in a previous paper 19 and for lack of space will not be developed here. It must be mentioned that the solution is based on a modified Reynolds equation that includes mass conservation and is solved by finite element method.…”

Conformal elastohydrodynamic lubrication analysis for engine bearing design: A brief review

“…Three treatment stages are typified by a crude truncation of negative pressures [1] and by several numerical methods to impose either mass-generating Swift-Stieber (SS) [3,9,10] or mass-conserving Jakobsson-Floberg-Olsson (JFO) [26,27,32] boundary conditions. Several authors address the effects of such fluid properties as piezoviscosity [5,52,56] and non-Newtonian behaviour [52]. Piezoviscosity has generally been found to have a relatively small effect on performance of rod bearings under typical operating conditions, where the dependency of viscosity on the shear rate also plays a secondary role.…”