Fracture mechanics-based criteria for fatigue fracture of rolling bearings under the influence of defects

Fatigue tests were carried out on real bearings with various types of artificial defects on their outer-ring raceways. Finite element analysis (FEM) revealed that the stress intensity factor (SIF) ranges and stress ratios were complex and variable, depending on the gap fittings between the outer rings and housings, as well as on the sizes of the initial defects, both of which influenced the fatigue thresholds of the bearings. In order to establish a comprehensive evaluation of fatigue limits under several combinations of bearing geometries and defect sizes, fatigue crack-growth thresholds were also measured at different stress ratios by focusing on crack-closure behaviour. Based on all of the analytical and experimental results, fracture mechanics-based criteria were proposed for the assessment of fatigue fracture in rolling bearings.