Finite Element Analysis of Fretting Stresses

Abstract

Clamped contacts subjected to vibratory loading undergo cyclic relative tangential motion or micro-slip near the edges of contact. This cyclic micro-slip, known as fretting, leads to removal of material through a mechanism known as fretting wear and formation and growth of cracks through a mechanism known as fretting fatigue. In aircraft, fretting fatigue occurs at the rivet/hole interface leading to multisite damage which is a potential failure mechanism for aging aircraft. A finite element model of a current fretting fatigue experiment aimed at characterizing fretting in riveted joints is detailed. A non-symmetric bulk tension is applied to the specimen in addition to the loads transferred from the fretting pad. The model is verified through comparison to the Mindlin solution for a reduced loading configuration, in which the bulk tension is not applied. Results from the model with the bulk tension show that the distribution of micro-slip in the contact is not symmetric and that for some loads reversed micro-slip occurs. Finite element results are given for the effects that four different sets of loading parameters have on the maximum tensile stress induced by fretting at the trailing edge of contact. It can be shown using multiaxial fatigue theory that this stress controls fretting fatigue crack formation. This maximum tensile stress is compared to that of the Mindlin solution for a symmetric distribution of micro-slip. This stress is also compared to that of a variation based on the Mindlin solution for the cases with a non-symmetric distribution of micro-slip. It is concluded that the solution based on the Mindlin variation and the full finite element solution lead to similar predictions of the maximum tensile stress, even when the shear traction solutions differ significantly.

Improved High-Cycle Fatigue (HCF) Life Prediction

“…Prior applications have demonstrated that a good approximation is just to add on the bulk stress. This works particularly well at the trailing edge (McVeigh & Farris 1997). The results from the finite element analysis (Figure 6B.23) show that indeed, the effect of the bulk loading is to add on the magnitude of the bulk stress value at the trailing edge.…”

A quantitative approach of Ti–6Al–4V fretting damage: friction, wear and crack nucleation

“…Future research will now focus on finest crack nucleation investigations [24,25] to deepen the physical interpretation of the critical length parameter ( c ) [26,27], and to compare the given approach with new developments based on "notch similitude" [28,29].…”

A practical methodology to select fretting palliatives: Application to shot peening, hard chromium and WC-Co coatings

“…Note that this first description was supported by the fretting map concept first introduced by Vingsbo [3] and completed by Vincent and co-authors [4]. Quantitative approaches have since been developed to formalize either the cracking phenomena from multiaxial fatigue approaches [5][6][7][8][9] or wear kinetics based on a dissipated energy description [8,10]. However, very little has been done to provide a global description of wear and cracking induced by fretting loadings.…”