Fatigue Assessment of Notched AM Scalmalloy Incorporating Surface Roughness in an Energy-Based Framework

In engineering practice, additively manufactured (AM) metal and metal alloy structural components, which often contain geometric discontinuities to fulfil functional requirements, are subjected to cyclic service loads. Among the possible loading configurations, far-field Mode I loading is frequently considered as a nominal reference condition. Within this context, a methodology for the fatigue assessment of notched AM Scalmalloy components subjected to Mode I far-field loading is proposed, combining the Strain Energy Density (SED) approach with a multiaxial critical plane-based fatigue criterion. The fatigue assessment is carried out at a verification point whose position is defined as a function of the characteristic length of the SED control volume for Mode I loading, determined through two alternative procedures, and of the surface roughness of the component. The proposed methodology is validated against experimental fatigue data available in the literature for AM Scalmalloy specimens featuring a circumferential semi-circular notch and subjected to Mode I far-field cyclic loading, which induces a locally multiaxial stress state at the notch root, given that the formulation does not rely on material-specific assumptions and could in principle be extended to other notched AM metal and metal alloy components.