Synergistic Effects of Notch and Volumetric Defects on Fatigue Performance of Additive Manufactured Parts

The usage of additively manufactured (AM) notched components for fatigue-critical applications presents non-trivial challenges, such as the ubiquitous presence of volumetric defects in AM parts. Volumetric defects accelerate fatigue crack nucleation, impact short crack growth, and are near-impossible to fully eliminate. This study investigated the synergistic effects of volumetric defects and notch geometry on the fatigue behavior of L-PBF AlSi10Mg and 17-4 PH SS notched specimens. The criticality of the defects on fatigue behavior is investigated using a non-destructive evaluation technique. A classical linear elastic fracture mechanics (LEFM) approach was modified and used to quantify the effects of several factors including notch geometry, defects’ size, and location, on the fatigue crack initiation behavior. The modified LEFM approach utilized X-ray computed tomography data and linear elastic finite element analysis of local stresses in different notch geometries; to calculate and rank the mode-I stress intensity factors of all defects within a notched specimen. The proposed approach was validated by predicting the volumetric defects’ criticalities and confirming them based on fractography.