On the effect of the node and building orientation on the fatigue behavior of L-PBF Ti6Al4V lattice structure sub-unital elements

Despite the great potential of additively manufactured (AM) metallic lattice materials, a comprehensive understanding of their mechanical behavior, particularly fatigue, has yet to be achieved. The role of the sub-unital lattice elements, that is, the struts and the nodes (or strut junctions), is rarely explored, even though it is well known that fatigue is a local phenomenon, determined by the small features of a structure (defects and local geometrical discontinuities). In this work, the mechanical behavior of nodes and struts has been investigated by designing laser powder bed fusion (L-PBF) Ti6Al4V single strut specimens, with a node placed in the central part of the gauge length. The specimens were manufactured according to four different building orientations, namely, 90°, 45°, 15°, and 0° to the build plane. The influence of the fillet radius at the node and of the printing direction on the fatigue strength has been examined.