A comparison of fatigue analysis methods for L-PBF net-shape surfaces in Ti6Al4V parts

The fatigue performance of additive manufacturing components is strongly limited by the surface topology, in particular considering the effect of the surface orientation. In the present study, Ti6Al4V laser powder bed fusion (L-PBF) net-shape specimens were printed considering four critical orientations to investigate and compare HCF fatigue properties and two different fatigue assessment methods. Detailed X-ray Computer Tomography (XCT) allowed us to carry out numerical simulations of the 4-Point Bending test samples, by adopting the critical distance method (TCD method). Endurance limit predictions based on the most critical valleys were performed by TCD and compared to predictions made with a Fracture Mechanics model that relies on simple profile roughness parameters. Comparison of the methods show that TCD inherently includes the shielding effect and it can better account for isolated features, while FM is more rapid and conservative.