Study on the effect of smearing on rolling contact fatigue

Bearings in wind power gearboxes and electric vehicle motors operate under challenging conditions such as high speeds and heavy loads, which can lead to smearing. Although smearing is a common early-stage bearing damage, its impact on rolling contact fatigue (RCF) life remains poorly understood. This study investigates the effects of smearing on RCF life in a controlled laboratory setting. Rollers undergo a sequence of smearing and RCF life tests, experiencing pure sliding during smearing generation and pure rolling in life tests, with rolling direction preserved in both. Post-test metallographic analysis identifies the main crack initiation point, propagation angle, and spalling depth on roller cross-sections. Statistical analysis of fatigue life assesses the influence of varied smearing conditions on roller life. Roller failures typically initiate in smeared areas where the material microstructure has been altered because of smearing. Roller fatigue life decreases as smearing load and speed increase. This study provides new insights into the impact of smearing on rolling contact fatigue life.