Fretting fatigue of 42CrMo4+QT steel: Experimental and numerical assessment

•Fretting fatigue tests of 42CrMo4+QT steel performed with varying bridge pad radii.•Qualitative variation in crack initiation was observed with the number of cycles.•This phenomenon was successfully modeled using elasto-plastic material behavior.•Among the 11 criteria tested, Papuga’s QCP method yielded the most accurate results. This paper focuses on an experimental and numerical assessment of fretting fatigue in cyclically loaded specimens from 42CrMo4+QT steel in contact with bridge pads of the same material. Four different pad configurations were employed, varying the radii of the pad legs, to achieve various stress gradient conditions in the fatigue process zone. A qualitative change in terms of the number of contact initiation locations observed in relation to fatigue life served as one of the aspects of the evaluation of a set of 11 fatigue prediction methods. It was observed that elastic–plastic stress analysis is crucial for capturing this phenomenon. Among the tested methods, Papuga’s quadratic parameter criterion (QCP) performs best in terms of risk assessment of crack initiation and prediction of its location.