Fatigue of Additive Manufactured Materials: Design Allowables and Defect CriticalityTuesday (26.05.2020) 13:30 - 14:10
As the great potentials of additive manufacturing (AM) has urged the industry to adopt this advanced technology, there are still major challenges to be resolved. Some of these challenges include qualification, certification and standardization, as well as validated design tools. For additively manufactured parts to be trusted in load-bearing, safety-critical applications, their structural integrity must be well understood, especially under cyclic loading. Bridging this gap is a complex undertaking, as there are many challenges specific to characterizing the behavior of additively manufactured parts. Any changes in feedstock characteristics, as well as design, process, post-process parameters can greatly impact the microstructure and mechanical properties. For example, the mechanical properties of AM laboratory specimens may not be representative of those associated with service parts; this is primarily due to differences in geometry/size, which can affect the thermal histories experienced during fabrication. The variation in thermal history affects the defects inherent to additively manufactured parts such as surface roughness, porosity, and lack of fusion between subsequent layers which can negatively impact the fatigue resistance. This presentation will provide an overview of the challenges facing the community with regards to generating design allowables for additively manufactured materials and suggest that understanding the defect critically along with having access to effective nondestructive testing methods or validated process simulations might be a more reasonable solution.