Strain based finite fracture mechanics for fatigue life prediction of additively manufactured samples

Abstract

A novel failure criterion, named Strain-based Finite Fracture Mechanics, is proposed to predict the fatigue life of additively manufactured notched components under uniaxial loading conditions. The model relies on the simultaneous fulfillment of two conditions: a non-local strain requirement and the discrete energy balance. The inputs of the model are strain and the stress intensity factor at failure, which depend on the number of cycles according to power law equations. The inputs can be obtained based on strain-life and stress intensity factor-life data from plain and notched specimens. The present approach is comprehensively validated against experimental datasets on additively manufactured samples from the literature for different materials, raster angles, notch geometries and loading conditions. Predictions by other approaches, such as Finite Fracture Mechanics (in its original stress formulation) and the Theory of Critical Distances, are also considered, for the sake of completeness. Results show that, in general, the proposed strain-based model is more accurate and provides consistently precise predictions across different cases.