The contrast of simplicity and accuracy in modeling multiaxial notch fatigue

Abstract

The fatigue assessment of notches under multiaxial and non-proportional service loading is challenging. Simple models (e.g. local strain approach based on normal stress and strain) are of poor quality for this general case of stress states and ductile material behavior. Advanced approaches show high accuracy, but require additional material testing and calibration. From an engineering point of view, deviations are tolerable to a certain extent. This contribution introduces two approaches for modeling multiaxial notch fatigue which are easy to apply. The first approach is an extension of the classical local strain approach. The second approach implements a simplified multiaxial notch approximation which enables the use of the extended short crack model in practical applications. A large database with experiments on notched components under multiaxial stresses is set up and used to validate the proposed algorithms. Results show the effectiveness of both approaches for ductile steels. Both approaches can be useful for engineers who are faced to multiaxial fatigue of notched components.