Damage evolution ahead of sharp notches under cyclic loading

The evolution of cyclic damage ahead of sharp notches has been investigated experimentally. The results are analyzed in terms of a loading parameter ΔBvm which is derived from averaging the calculated local stress and strain distribution at the notch root over some microstructure related size scale. This loading parameter is suggested to bridge the gap between the stress controlled crack initiation and the stress intensity controlled macrocrack growth. This approach proved to be well suited in describing the striking phenomena of the fatigue behaviour of notched bodies, especially the damage evolution ahead of sharp notches till crack initiation and the growth of (mechanically) short fatigue cracks. (orig.)