Very low cycle fatigue life evaluation models and validation using notched compact tension test data. (February 2022) - Lee, Jong-Min
Highlights: Very low cycle fatigue life evaluation methods considering multiaxial stress states. A strain-based fatigue life evaluation model with void shrinkage ratio depending on the plastic strain range. An energy-based fatigue life evaluation model giving the relationship between fatigue life and fracture strain energy. Evaluation models determined from smooth and notched bar tensile test and fatigue life curve. Validation of the proposed methods against notched C(T) test data of two materials. Abstract: Strain-based and energy-based model are proposed for the evaluation of very-low cycle fatigue life considering multi-axial stress states. In the strain-based model, based on void growth and shrinkage, the void shrinkage ratio is proposed as a function of the plastic strain range. The energy-based model is developed by considering stress triaxiality in the relationship between fatigue life and fracture strain energy. For validation, two models are determined using smooth and notched bar tensile test and best-fit fatigue life curves of SA508 Gr.3 and TP316L. Fatigue lives predicted by both models are within 85% of experimental values in all cases.