S ai Sreenivas Penkulinti

Abstract

Whether it’s automotive, bio-mechanics or aeronautical industry, additive manufacturing (AM) is already in reality due to its wide range of advantages. But limitations, like the presence of defects induced by the fabrication process that depends on the input process parameters, continue to be a crucial issue for the design of industrial components regarding fatigue damage. The present work aims to use numerical simulation to study and understand the impact of typical AM defects, and especially the lack-of-fusion (LoF) defects, on the multiaxial fatigue behaviour of high-strength materials. Studies have shown that the local approaches lead to conservative fatigue behaviour predictions [F. Morel et al., International Journal of Fatigue, 2009, A. Karolczuk et al., Computational Materials Science, 2008, Y. Nadot & T. Billaudeau, Engineering Fracture Mechanics, 2006], and the stress and strain distributions around the defects depend on the size, position and morphology.  For that, a numerical methodology has been formulated to carry out simulations on 10 LoFs (real defect geometries observed from CT scans) that were induced during the fabrication of TA64 using an SLM process. Simulations were performed on ideal spherical defects at different loading modes (tension, torsion, and tension-torsion) to determine the stress distribution around the defect. Repeating the same on 10 critical LoFs and able to compare the results with some experimental data. The analysis helps to quantify the impact of stress gradient (resulting from the different defect morphology) on fatigue behaviour under multi-axial loading conditions.

Keywords: Additive Manufacturing, Defect, Multiaxial fatigue, Finite Element Analysis.

Session