Propagation of Large Spalls in Rolling Bearings

Abstract

The paper focuses on studying the propagation of large spalls on the raceways of rolling bearings. This is done by means of experiments and modelling. It is shown that the application of a relatively simple model to describe a spall evolution in time in rolling bearings is feasible. The proposed model is validated using experiments, where rolling bearings with initial pre-damage have been tested and the surface spall progression has been monitored in time. Surprisingly, spall progression in rolling bearings appears to be correctly described by a model of damage initiation. Without the need of a more sophisticated crack propagation model, at least this seems to be the case for a relatively large spall (larger than the Hertzian contact). Where the effects of the pressure build up from lubrication can be ignored. However, dynamic effects cannot be disregarded, since they seem to be the driving force for the propagation direction in some cases. The effect of the shape, size of the initiation point and load sequence is studied as well as the shape of the contact (line or elliptical), giving interesting insights of the propagation mechanisms.

Standstill Corrosion and Spall Propagation in Rolling Bearings

“…This paper is a follow-up investigation of previous work by the author [8] on spall propagation in bearings. The present work is connected to the previous one in the sense that once the corrosion pitting is initiated the propagation into spall is carried out using exactly the same model as in [8].…”

“…From the generated surface defects via pitting corrosion, spall can be initiated and propagated once the overrolling process starts. To simulate this step, a spall propagation model previously developed [8] is used. A simple flowchart of this model is given in Fig.…”

“…6. The description of the model and the validation with experiments will not be repeated here since a detailed description is given in [8]. However, a simple explanation of the main features will be described here for the sake of completeness.…”

“…However, a simple explanation of the main features will be described here for the sake of completeness. It is assumed that the overlapped corrosion pits make relatively large surface depressions, thus during overrolling oil cannot be pressurized and it will escape from the Hertz contact, collapsing the lubricating film, as in a large spall [8]. For many real cases, this might be a conservative approach since the corrosion pitting damage could be milder, so at the beginning the contact could indeed be properly lubricated.…”

New Damage Accumulation Model for Spall Propagation Mechanism in Bearing Raceways

“…Morales-Espejal et al [ 13 , 14 ] focused on the progression of the initial damage around an indentation. They introduced a physically-based surface rolling contact fatigue (SRCF) model to predict material particle detachment, and used this model to describe the mechanism that controls damage propagation for large spalls (larger than the Hertzian contact width) [ 15 ]. In this model, the damage propagation is simulated by removing material elements that accumulate fatigue damage.…”