Fatigue Strength Evaluation of Notched Ductile Steel Specimens Using Critical Distances

In the case of AISI 304L austenitic stainless steel it was found that the fatigue strength of specimens characterized by the presence of blunt notches cannot be rationalized either in terms of linear elastic local stress or nominal stress amplitude. This fact was related to the high level of ductility shown by this material also in the case of high cycle fatigue regime. Therefore, in this paper some classical fatigue design methodologies are extended to account for this aspect also in the case of severe notches. On this basis a FEM oriented extension of the concept of geometric elastic stress concentration factor is proposed.