Fatigue strength assessment of additive manufactured components considering local quality and geometry using the theory of critical distances and 4R method

Abstract

Laser based powder bed fusion (L-PBF) manufactured components are typically used in weight-critical fatigue loaded applications. Building orientation and parameters have strong influence on fatigue performance. Multiparametric method for fatigue performance analysis is applied on high-strength L-PBF specimens’ fatigue test results in this study. The fatigue strength analysis was conducted on unnotched and notched specimens with a consideration of local quality. The defect and surface profiles which defines local quality are characterized with the fractography. The results suggest that local quality influenced by building characteristics can be assessed when effective stresses are obtained by the Theory of Critical Distances (TCD) via finite element analysis. Fatigue strength assessment of notched components benefit from a consideration of local cyclic behaviour with the 4R method. Consequently, multiparametric method for fatigue strength assessment with single FAT class was proposed for AM-components.