Non-Newtonian and running-in wear effects in journal bearings operating under mixed lubrication

For the study of mixed lubrication in dynamically loaded journal bearings, this paper employs a combined experimental and simulative approach. Extensive measurements on a journal bearing test rig with a low-viscosity 0W20 multi-grade lubricant with a strong Non-Newtonian behaviour provide the basis for the investigation of the lubrication conditions in journal bearings. In this paper, temperature effects and the influence of running-in (breaking-in) wear are investigated. To this task, a high dynamic load is applied to the journal bearing under test. To vary the lubrication conditions, only the journal speed is changed. To investigate the lubrication conditions a detailed and validated simulation approach is utilized that takes into account both the piezoviscous effect and the non-Newtonian behaviour of the investigated lubricant as well is able to describe metal–metal contact. With this combined approach the run-in process of the journal bearing under test can be investigated as well as the role of temperature settling effects.