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Laser Powder Bed Fusion (L-PBF) provides ample freedom to fabricate lattice materials with tailored micro-architecture. Nevertheless, small-scale structures often suffer from a wide range of morphological defects, which impact the macro-scale mechanical properties. In this work, prominent morphological factors including geometric irregularities (surface notches and cross-section deviation), node geometry and printing direction are assessed for four batches of L-PBF Ti-6Al-4 V cubic lattice specimens, and their fatigue behavior compared. The results show that smoothing the strut fillets at their node remarkably improves the S-N curves and that the printing direction impacts both the fatigue strength and the failure behavior.

The Strain Energy Density (SED) based fatigue criterion proposed in Benedetti et al. Int. J. Fatigue 2020;133:105397 is further developed to incorporate residual stresses (RS). Mechanical and residual stresses are treated separately. The formers are encapsulated in the form of SED associated to stress range and maximum SED. The work done when tensile mechanical strains fluctuate in the presence of compressive RS is added to the equivalent SED of the fatigue criterion. This is calibrated and validated using the results of an extensive experimental campaign aimed at exploring the effect of shot-peened induced RS on plain and notch fatigue strength of Al-7075-T651.