Local Fretting Regime Influences on Crack Initiation and Early Growth
Résumé
An investigation of fatigue crack initiation and propagation under fretting conditions is described in which both experimental and theoretical approaches are used. Fretting tests were conducted on an aerospace aluminium alloy. The approach presented here aims to describe the propagation of a fretting crack through a step-by-step understanding of the different stages of its life (1) Stage I crack initiation, i.e., sites, growth directions and fracture mode, (2) Stage I-to-Stage II transition as a result of the competition between failure modes, i.e the branching depth and the growth direction after branching. This methodology was successfully applied to fretting fatigue data obtained under the Partial Slip Regime (PSR). Pertinent parameters were proposed to deal with items (1) and (2) depending on the ranges of shear and tensile stresses and their respective roles in crack growth. This step-by-step methodology is used here to analyze the influence on crack initiation and propagation of the local fretting regime and the associated mechanical stress-strain state.
