Experimental Observation and Numerical Simulation of Rheological Properties of Lubricating Films under Different Sliding-Rolling Ratios

By supplementing a friction measurement unit to conventional ball-and-disc optical device, the friction coefficient and film thickness were able to be acquired simultaneously under random sliding-rolling ratios. And hence the lubrication state can be well recognized. By employing reference oil of FVA3, the variations of friction coefficient with sliding-rolling ratio, speed and load were analyzed. In combination with interferograms, the lubrication regime and the thermal effect considering in friction measurement were validated. It is also supposed that mixed lubrication regime existed on the 3D map of friction coefficient at low speeds. Finally, a rheology model based on time recovery principle was employed to predict the fiction coefficient and film thickness corresponding to the experimental parameters. Good agreements were achieved between numerical predictions and experimental measurements, confirming both the accuracy of the test method and feasibility of the rheology model.