A micromechanical approach to fatigue in small notches

The present work shows the application to small notches of a micromechanical model which describes the growth of a short crack across the steep stress gradient generated at the root of a notch. The model, based on the theory of distributed dislocations, takes into account the interaction between short cracks and material barriers such as grain boundaries. The term 'small notches' refers in this paper to stress raisers the size of which is of the same order as the characteristic microstructural unit of the material. Typical examples are superficial scratches, corrosion pits, inclusions or pores. Comparisons between predicted fatigue limits and experimental results reported in the literature for different materials containing small artificial defects are shown and discussed.