Influence of geometric imperfections on the mechanical behavior for Invar 36 alloy lattice structures fabricated by selective laser melting

The studies on the mechanical behavior of Invar 36 alloy lattice structures prepared by additive manufacturing process are limited. In this paper, the influence of geometric imperfections generated during the additive manufacturing process on the mechanical behavior of Invar 36 alloy lattice structures was investigated. To realize lightweight and high load-bearing capacity, lattice structures with different fillet radii were designed and subsequently fabricated by selective laser melting (SLM) process. Compression tests based on in-situ X-ray computed tomography (X-CT) were conducted to evaluate the manufacturing quality and corresponding mechanical behavior. Differences between design models and fabricated lattices were quantitatively compared. Various geometric imperfections, including strut waviness, varying cross-sections, visible surface defects, visible defects at strut intersections, and roughness on struts, were observed. Additionally, deformation patterns at different loading stages were also obtained, primarily manifesting as the yielding of the nodes and the buckling of the struts. Importantly, struts with varying cross-sections possess the most significant influence on the deformation behavior.