Improved Fatigue Life Analysis of Pre-Dented Raceways Used in Bearing Material Testing

• Published in: Bearing Steel Technologies: 11th Volume, Advances in Steel Technologies for Rolling Bearings pp. 167 - 191
• Main Authors: Gabelli, Antonio, Morales-Espejel, Guillermo E.
• Format: Book Chapter
• Language: English
• Published: 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 ASTM International 01.11.2017
• Subjects: Indents; Particle Denting; Rolling Contact Fatigue Testing; Surface Initiated Spalling; Surface Rolling Contact Fatigue
• ISBN: 9780803176430; 0803176430
• DOI: 10.1520/STP160020160154

Endurance testing of bearing samples with pre-dented raceways is a testing methodology often used in bearing material development. The main advantage of this type of test is the drastic reduction of the time required to carry out the measurement of bearing life. This method provides direct experimental data on the fatigue properties of the raceway material that are needed in case the fatigue strength of the raceway is enhanced using specific heat treatments or other means. An in-depth tribological fatigue analysis is applied to pre-dented bearings to get a better inside view of the damaging mechanisms taking place at the stress risers of the raceway. The analysis of the dent spalling process includes the onset and the progression of the fatigue damage originating from the dent. A novel rolling contact fatigue model, with the ability to separate the survival probability of the raceway surface from the subsurface region of the rolling contact, is applied. Results are presented showing a good ability to reproduce the observed endurance test data under a variety of testing conditions. The new model is used to study the effect of dent size, load, and lubrication of pre-dented bearings. It is found that the separation of the surface fatigue from the subsurface material degradation offers new capabilities for the tribological modeling of surface rolling contact fatigue and that this improves the correlation with the experimental observations. Examples of the application of the new method for accounting rolling contact fatigue of pre-dented bearings are given, showing the ability to describe the strengthening mechanisms observed with different bearing materials and heat treatments.