Microstructural fatigue mechanisms: Cyclic slip irreversibility, crack initiation, non-linear elastic damage analysis

Depending on material and details of cyclic loading conditions, fatigue damage develops and spreads by various modes of crack initiation and subsequent crack growth. In order to gain a deeper understanding of the underlying microstructural mechanisms, many details must be considered. The present study focuses on just a few specific aspects, namely the role of cyclic slip irreversibilities, the significance of fatigue crack initiation in high and ultrahigh cycle fatigue (HCF, UHCF) and, finally the analysis of non-linear effects of elasticity and compliance of fatigued specimens, as a promising non-destructive in situ fatigue damage diagnosis tool. Selected experimental data obtained on different materials will be considered to illustrate the issues named above.

► Significance of cyclic slip irreversibilities: how do they relate to fatigue life?
► The importance of fatigue crack initiation in the HCF and UHCF regimes.
► Non-linear elasticity and compliance effects in fatigued metals: a new in situ damage diagnosis tool?