Generalised Neuber concept of fictitious notch rounding

The microsupport effect at sharp notches subjected to high-cycle fatigue can be described according to Neuber by averaging the maximum notch stress in a small material volume (microsupport length ρ*) at the notch root (radius ρ). The averaged stress may be expressed by the maximum stress of a corresponding notch of an enlarged, fictitious radius, ρf = ρ + sρ*, where s is the microsupport factor. The status of Neuber’s concept within his general theory of notch stresses is reviewed, followed by more recent theoretical and application-relevant developments. The theoretical developments refer to the notch angle dependency of the support factor, to its value for pointed versus rounded notches and to in-plane shear loading with out-of-bisector crack propagation. The application developments refer to the fatigue assessment of welded joints.