Influence of crack nucleation location on fretting fatigue crack path

Fretting is a contact phenomenon affecting the behaviour of metallic structural components subjected to vibrations or small oscillatory movements, and it has been recognized as the primary failure mode in many engineering applications. In more detail, due to the high stress gradients in the vicinity of the surface between two components in contact, the nucleation of cracks appears, thus leading to the failure of the metallic structure. In such a condition, the main cracks are expected to nucleate in correspondence to the stress concentration region, that is, the edge of the contact. However, cracks starting within the contact zone close to the edge are often experimentally observed. In the present paper, an analytical methodology recently proposed for the fretting fatigue assessment of metallic structures is employed in order to simulate an experimental campaign available in the literature, carried out on a 7050-T7451 aluminium alloy. Such a methodology is based on the joint application of the multiaxial fatigue criterion by Carpinteri et al. and the critical direction method by Araújo et al. First, the crack path orientation is determined for each loading configuration tested in the above-mentioned experimental campaign, by assuming the crack nucleation location in correspondence to the contact trailing edge. Then, a crack nucleation location inside the contact surface is adopted, in order to evaluate the crack path orientation. Finally, the results obtained are compared to the experimental observations available in the literature.