Nominal stresses to assess damage in notched additively manufactured steel subjected to constant and variable amplitude multiaxial fatigue loading

The present paper reports on the use of the Modified Wöhler Curve Method (MWCM) applied along with nominal stresses to estimate lifetime of notched additively manufactured metallic materials subjected to constant and variable amplitude multiaxial fatigue loading. The MWCM is applied by defining the critical plane via the direction that experiences the maximum variance of the resolved shear stress. In this setting, owing to the fact that the shear stress resolved along this direction is a monodimensional stress quantity, fatigue cycles are counted directly by using the standard Rain-Flow method. Based on a large data set taken from the literature, the validation exercise being performed strongly supports the idea that the MWCM used in conjunction with nominal stresses is successful in estimating fatigue damage also in notched 3D-printed metallic materials subjected to constant/variable amplitude multiaxial load histories.