  Selective Laser Melting (SLM) technology has undergone significant
development in the past years providing unique flexibility for the fabrication
of complex metamaterials such as octet-truss lattices. However, the
microstructure of the final parts can exhibit significant variations due to the
high complexity of the manufacturing process. Consequently, the mechanical
behavior of these lattices is strongly dependent on the process-induced
defects, raising the importance on the incorporation of as-manufactured
geometries into the computational structural analysis. This, in turn,
challenges the traditional mesh-conforming methods making the computational
costs prohibitively large. In the present work, an immersed image-to-analysis
framework is applied to efficiently evaluate the bending behavior of AM
lattices. To this end, we employ the Finite Cell Method (FCM) to perform a
three-dimensional numerical analysis of the three-point bending test of a
lattice structure and compare the as-designed to as-manufactured effective
properties. Furthermore, we undertake a comprehensive study on the
applicability of dimensionally reduced beam models to the prediction of the
bending behavior of lattice beams and validate classical and strain gradient
beam theories applied in combination with the FCM. The numerical findings
suggest that the SLM octet-truss lattices exhibit size effects, thus, requiring
a flexible framework to incorporate high-order continuum theories.
