Robust Determination of Fatigue Crack Propagation Thresholds from Crack Growth Data.

The robust determination of the threshold against fatigue crack propagation ΔKth is of paramount importance in fracture mechanics based fatigue assessment procedures. The standards ASTM E647 and ISO 12108 introduce operational definitions of ΔKth based on the crack propagation rate da/dN and suggest linear fits of logarithmic ΔK- da/dN test data to calculate ΔKth. Since these fits typically suffer from a poor representation of the actual curvature of the crack propagation curve, a method for evaluating ΔKth using a nonlinear function is proposed.

Damage tolerant design of additively manufactured metallic components subjected to cyclic loading: State of the art and challenges.

Undoubtedly, a better understanding and the further development of approaches for damage tolerant component design of AM parts are among the most significant challenges currently facing the use of these new technologies. This article presents a thorough overview of the workshop discussions. It aims to provide a review of the parameters affecting the damage tolerance of parts produced by additive manufacturing (shortly, AM parts) with special emphasis on the process parameters intrinsic to the AM technologies, the resulting defects and the residual stresses.