A study of fretting fatigue incorporating sharp corner contact geometry.

Fretting fatigue occurs when components are in contact and subjected to cyclic loads or vibrations. The following research programme investigates the fretting fatigue phenomenon using a specific flat contact geometry encompassing sharp comers. The pressure distribution at the contact interface is fundamentally important in the understanding of fretting fatigue problems. In the case of sharp comer contacts, the analysis of the pressure distribution results in an infinite gradient occurring at the edges of the contact. The infinite gradients generate deformation singularities and closed form solutions are not available for this contact geometry. The specific contact pressure generates friction forces, which affect the nucleation and growth of dominant fretting cracks by influencing the stress distributions in the region of the contact.The current research programme presents a method of analysing flat contacts containing sharp comers. The method includes the development of a finite element solution capable of accurately predicting the friction force behaviour observed in fretting fatigue. The subsequent numerically determined stress distributions in the contact region are then used to generate a multiaxial stress concentration factor, which provide the basis for a fretting fatigue life prediction method. Furthermore, the research programme investigates the phenomenological effects observed during fretting fatigue. The study investigates friction behaviour and its effects on the initiation of fretting cracks and fretting fatigue lives.