Fretting fatigue strength evaluation of scaled press-fitted railway axle containing a circumferential groove defect

Abstract

Fretting fatigue cracks can occur in the wheel seat of railway axles, posing a risk to safe operation. This study investigates the critical crack depth that ensures the fatigue strength of railway axles remains within acceptable limits. Fretting fatigue tests were performed on scaled press-fitted axles with circumferential groove defects of varying depths. Results showed that as the defect depth increased, the fretting fatigue strength decreased. An elastoplastic FE simulation model was developed based on these experimental findings, analyzing both conditions with and without fretting wear. The analysis revealed that the failed specimen, compared to the non-failed one with the same defect depth, exhibited at least a 5 % increase in maximum stress at the crack initiation point and over a 10 % increase in the high-stress region due to higher nominal stress. When fretting wear-induced profile changes were considered, crack initiation could be predicted using a modified wöhler curve method (MWCM) and critical plane method. To simplify engineering simulations, an FE model without fretting wear was used, with a coefficient K = 1.133 ± 0.1 determined from published experimental data. Combining this coefficient with the MWCM criterion, the critical defect size under allowable stress conditions was predicted, yielding results in close agreement with experimental data.