Non-Newtonian and Thermal Effects in Journal Bearings

An experimental investigation was conducted to study the simultaneous effects of Non-newtonian lubricant behavior and thermal dissipation during hydrodynamic lubrication of a journal bearing. The results show that thermal effect is an important factor not to be neglected in any theoretical analysis of hydrodynamic lubrication. When we compare a non-Newtonian oil (2.25 percent PIB L80 in Vitrea 32) and a Newtonian oil of the same zero shear rate viscosity (Vitrea 320), they show the same load capacity (or Sommerfeld number) up to a relative eccentricity ε = 0.5. Beyond this point, the Newtonian oil exhibits a higher Sommerfeld number. Due to viscous dissipation, the normal stresses exhibited by the non-Newtonian oil cannot compensate for the loss of viscosity by shear thinning.