Improve simulation of plain bearings in dry and mixed lubrication regime by defining locally resolved dry friction coefficients

Asperity friction is a main indicator for wear and heat conduction [1]. It occurs when thickness of oil film shrinks due to high load or slow speed. Friction is scientifically well known as long as it is dominated by laminar oil film effects. If film thickness shrinks, the friction coefficient depends mainly on surface properties. This inaccuracy is normally preceded in simulation by using friction coefficients defined by Coulomb’s law [2]. To improve simulation results, the simulated friction moment was compared to measurement on a component test rig. Friction moment is produced on every square millimetre of the bearing surface, but can only be measured as an integral. Research findings show that measured results can’t be met by using one global dry friction coefficient for the whole bearing surface, even though it is material dependent. By introducing locally resolved and asperity pressure dependent dry friction coefficients, it was possible to adapt the simulated friction moment to measure one with a deviation of less than 5 percent. By means of simulation it was possible to develop locally resolved results based on integral measurements; and improve modelling the frictional state of mixed lubrication.