THE INFLUENCE OF WALL THICKNESS ON THE FATIGUE LIMIT OF V-NOTCHED BARS MADE OF AS-CAST OR HEAT TREATED DUCTILE IRON

摘要

The paper illustrated the application of a fatigue testing procedure in presence of notch effects. The material fatigue behavior has been characterized experimentally by means of smooth specimens, in order to derive the plain fatigue limit, and by means of sharply notched specimens, in order to found the threshold value of the stress intensity factor. All theoretical estimations indicate a sharp behavior of the notched specimens, i.e. the 0.1 mm notch tip radius is ineffective on the fatigue strength, which can be assimilated to that of notch having a zero notch tip radius. A complete set of data to be used in fatigue design was provided Many efforts in terms of investigation at microscale are now continuing to better understand the microstructure response vs wall thickness under severely notched conditions, since the threshold value ΔKth, remains consistent.