Inertia, shear-thinning and thermal effects on connecting rod bearing behaviour

Abstract

In earlier works Fantino et al [5–6] and Martin [8] give a summary of the studies performed in connecting rod bearings where elasticity and inertia effects from solids were included. In these theoretical and experimental works, it has been shown the strong influence of the housing deformations as well as the shape defects in the connecting rod bearings performances. More recently, the study of bearings subjected to dynamic loads has showed that inertial effects and surface accelerations play an important role in the bearing response (Bou-Said et al [3]). Although the lubricant was considered Newtonian, this assumption is no longer valid with modern lubricant. In industrial applications, long soluble polymer chains are added to mineral lubricants to optimise properties under different operating conditions. The addition of these polymers results in a viscosity drop for shear rate values ranging from 10+6 to 10+8s−. A previous study from Bou-Said et al [3] has examined the influence of fluid inertia, and effects of shear thinning in a connecting rod bearing behaviour under dynamic loading. In the present study we include the thermal effects which usually play an important role in bearing performances. Using all these assumptions (shear thinning and inertial properties of the lubricant, surface accelerations and thermal effects), the results show important differences in shaft responses compared to the classical cases.