Numerical investigation of the influence of defects on the multiaxial fatigue strength of additively manufactured alloys

Abstract

Laser Powder Bed Fusion (L-PBF) is one of the Additive Manufacturing (AM) techniques that have revealed salient advantages in enabling the fabrication of 3D parts with intricate shapes and added functionalities. Despite many advances, scientific challenges still exist. One of them, especially where the additively manufactured industrial components undergo fatigue loading, is the defects (gas pores and Lack of Fusions (LoFs)) that are induced during the fabrication process. The present work aims to investigate the influence of AM defects on fatigue strength under multiaxial loading conditions. From numerical simulations, the key question addressed is the impact of defects’ morphology on their criticality under multiaxial loadings. Finite Element (FE) elastic simulations at load ratio R = -1 under multiaxial loading conditions (tension, torsion and tension-torsion) have been performed on numerically generated spherical defect and LoFs obtained from micro-CT scans of additively manufactured TA64 alloy. The Crossland criterion (stress-based) was used to evaluate the fatigue strength and the obtained numerical results were compared with the available experimental results.