Prediction of fretting fatigue crack nucleation: comparison between non local fatigue stress analyses

Abtract Fretting-Fatigue problems are very complex to address due to the multi-axiality and the very sharp stress gradients imposed below the surface. Multi-axial and non local fatigue approach must be considered. An experimental cylinder/plane fretting fatigue analysis of a 35NiCrMo16 low alloyed steel was performed to investigate the incipient crack nucleation response at 10 cycles for various stress gradient conditions. Imposing elastic stress conditions, the Crossland fatigue approach is applied to predict the crack nucleation risk. This analysis confirms that a local stress analysis at the “hot spot” located at surface trailing contact border is not suitable because it sharply overestimates the cracking risk. Non local critical distance and stress gradient approach based on the Papadopoulos theory are applied. The stress gradient formulation provides less dispersive predictions.