Displacement controlled fatigue crack growth in inelastic notch fields: Implications for short cracks

Much has been written documenting the crack growth from notches which suggests that LEFM does not consolidate such data in a manner consistent with those of compact tension and other specimens with long cracks. Such crack growth data are reviewed and causes for the observed “short crack” effect are advanced. Situations where the crack is contained within the inelastic field of a notch are explored at length. A postulate is advanced to characterize crack growth for this case in terms of a pseudoplastic stress intensity factor defined in analogy to LEFM as well as a simple approach to deal with local crack closure. The postulate is shown to be consistent with experimental observations. Predictions of the growth of cracks in the inelastic field are made and shown to confirm observed growth rates and trends.