Spalling Life Prediction for Rolling Bearings Using a Model with Stress Intensity Factor and Statistical Evaluation of Non-Metallic Inclusions

Spalling, which can be classified into sub-surface and surface-originated types, is a major failure mode of rolling bearings due to rolling contact fatigue (RCF). Sub-surface originated spalling typically has a much longer life than surface-originated spalling, indicating that rolling bearings may often exhibit excessive durability in normal environments. Highly accurate prediction of bearing life for sub-surface spalling would enable the more active use of smaller products and contribute to resource conservation. ISO 281 provides a framework for integrated life prediction, taking into account the effect of lubrication conditions. However, it does not consider the effect of non-metallic inclusions, which can lead to sub-surface originated spalling. Previous studies have identified the mode II stress intensity factor (SIF) as the key driver of spalling initiated by internal defects such as inclusions, based on RCF tests with small artificial defects. Therefore, this study derives a life model using the range of SIF. Additionally, a novel and practical method that combines the life model with the statistical data on inclusion sizes is proposed to predict Weibull plots of spalling life.