Traction Prediction In Rolling/sliding Ehl Contacts With Reference Fluids
Machine elements such as rolling bearings and gears transmit forces and permit relative motion in concentrated contacts, whereby elastohydrodynamic lubrication (EHL) plays a major role in surface protection. The friction/traction in a rolling/sliding EHL contact is hard to predict due to non-Newtonian rheology and concomitant thermal effects. In the last decade, much effort has been made to study the EHL traction using reference fluids. However, considerable discrepancies still exist between predictions and measurements. This work continues the effort to predict the EHL traction with model fluids (mainly with squalane) and investigates the influence factors that lead to the differences between simulations and experiments. An EHL model has been developed for traction prediction accounting for non-Newtonian and thermal effects by embedding fluid models of thermo-physical-rheological properties (such as viscosity, thermal conductivity, shear thinning, and limiting shear stress) supported by independent high-pressure measurements. On the experimental aspects, traction curves have been measured on two traction machines with different contact geometries, i.e. twin-disc and ball-on-disc.