Estimation of crack paths at initiation stage under fretting high-cycle fatigue

Fretting fatigue represents a physical phenomenon that occurs at the interface between two assembly components, pressed in contact and subjected to tangential cyclic loadings. Such a phenomenon induces a multiaxial stress field characterized by severe stress gradients near the contact surface. Fretting fatigue is generally examined by means of a multiaxial fatigue criterion together with an averaging non-local approach. As a matter of fact, the output of a non-local approach represents the input for the fatigue criterion employed. In the present paper, crack paths at the initiation stage under fretting high-cycle fatigue loading are analytically evaluated by applying three different averaging non-local approaches. Such an evaluation is carried out by also using the critical plane-based multiaxial fatigue criterion proposed by Carpinteri and co-workers. The accuracy of the three non-local approaches above is estimated by analysing experimental data related to fretting high-cycle fatigue tests, performed on specimens made of AISI 1034 and 35NCD16 under cylindrical contact.