Prediction of cracking in Ti-6Al-4V alloy under fretting-wear: use of the SWT criterion

In order to predict the crack nucleation, the Smith-Watson-Topper criterion is used. This critical plane criterion is based on the calculations of the maximal normal stress and the maximal strain amplitude in the considered plane. The predicted location of the crack nucleation in the fretting scar coincides with the one observed in the fretting tests. To take into account the size effect in fretting, stresses are averaged on an elementary volume, which corresponds to the volume of an alpha grain. Shot peening is considered in the SWT criterion through an additional compressive stress, which reflects the compressive stress state induced by shot peening in the surface.