A comparative analysis between multiaxial stress and ΔK-based short crack arrest models in fretting fatigue

This paper presents a comparative analysis between a multiaxial stress and a stress intensity factor based fatigue model within the context of short crack arrest in fretting fatigue. The stress-based model involves the calculation of a multiaxial parameter at a critical distance from the contact. The critical distance is identified by means of plain fatigue limits and the threshold stress intensity factor range for long crack propagation. The ΔK-based model compares the mode I stress intensity factor range at a critical distance from the contact with the threshold stress intensity for crack propagation. In this case, the critical distance is defined as the crack transition length between the short and long crack regimes, which is obtained from the Kitagawa–Takahashi diagram. In order to carry out the comparative analysis, new fretting fatigue tests were performed with a pair of cylindrical pads pressed against a flat dog-bone specimen, both made of 7050-T7451 Al alloy. Three series of tests were conducted in the partial slip regime. Within each series the experimental conditions were identical, except the mean bulk load, which varied from a tensile to a compressive value until a run out condition was achieved. The results showed that the predictive methodologies provide different short crack arrest domains for the same contact configuration. The stress-based model yielded slightly better estimates of fatigue endurance than the stress intensity factor based model.