Inertia and Shear-Thinning Effects on Bearing Behavior With Impulsive Loads

Abstract

The study of bearings subjected to impulsive loads have previously showed that inertia effects and surface accelerations play an important role in the bearing response. Although the lubricant was considered Newtonian, this assumption is no longer valid with modern lubricant. In industrial applications, mineral lubricants are added to several long soluble chains of polymer in order to conserve optimum properties under different operating conditions. The addition of these polymers results in the drop of viscosity under high shear-rate, in the range of 10−6 –10−8 s−1 . This study presents a continuation of previous works. It examines the influence of both effects, the decrease in viscosity and the fluid inertia, in a journal bearing under impulsive loads. Using the power-law model, the results show important differences in shaft responses compared to the Newtonian cases. Furthermore, in high shear-thinning effects, a reduction of lubricant capacity to absorb sudden dynamic loads is observed.