Advances in multiaxial fatigue life prediction for components with stress concentrations

Methodologies for predicting the multiaxial fatigue life of notched components are reviewed and discussed. As background, a brief overview of approaches for predicting the multiaxial fatigue life of smooth specimens is presented. Representative test data generated prior to the mid 1980s are summrized to demonstrate complexities involved in the multiaxial fatigue behavior of notched specimens. During the past decade, research efforts on this topic have increased, with emphasis on the development of new multiaxial fatigue damage parameters and approaches for simulating notch elastic-plastic cyclic stress-strain behavior. Progress towards the application of simplified approaches, such as Neuber's rule, to the prediction of notch stress-strain behavior for proportional multiaxial loading is described. Other promising work for predicting notch stress-strain behavior under nonproportional loading is summarized. The newer approaches have considered blunt circumferential notches or shoulder fillets and are based on surface stress-strain behavior. Test data are shown which suggest that such approaches may not be adequate for other types of notches (e.g. splines) for which the effect of notch geometry and subsurface stress-strain distributions may be important. It is suggested that development of methodologies appropriate for certain categories of notches may be the most fruitful approach to take in future studies, rather than seeking a universal methodology.