ABSTRACT
The aim of this chapter is to discuss analytical models for the prediction of fatigue crack nucleation and early growth. The preliminary stage frequently takes a significant portion of the total fatigue life. The simplest models of fatigue crack nucleation are based on phenomenological scalar damage measures. Continuum damage mechanics is in fact an extension of classical mechanics of deformable media for modelling of various types of damage on the mesoscopic level. Continuum damage mechanics is a useful tool to generalize Miner’s rule and related phenomenological approaches in terms of continuum mechanics. Macrocrack initiation was treated in the framework of continuum mechanics. Two principal patterns of formation of macroscopic fatigue cracks are to be distinguished. First is the coalescence of microdefects into a connected damaged domain. The second mechanism consists of the formation of mesocracks, their growth along the surface and the beginning of their in-depth penetration.
