Strain concentrations in BCC micro lattices obtained by AM

The micro-lattices produced by additive manufacturing process (AM) represent a recent important advancement for engineering structural applications, in particular for weight-saving purposes. The design of the components manufactured with these meta-materials generally refers to the idealized structures. In reality, the geometry obtained by the AM process profoundly differs from the original one, in particular local geometrical irregularities were found to produce local stress and strain localizations which are difficult to be a-priori predicted by the analyses on the idealized structures. These geometrical defects may have a significant role for the structural integrity of the component and it is important to quantify their effect on the local stress and strain fields. In this study, we present an experimental investigation of a typical AlSi10Mg micro-lattice, namely the BCC cell. 3D tomography was used to reconstruct the original geometry and, successively, full-field digital image correlation strain measurements were performed to capture the localization of strains which are considered the precursor of the micro-lattice damage. The local strain measurements were used to calculate and classify the strain concentration factors arising from the geometrical irregularities. These results were compared with the finite element results obtained for the idealized and the real micro-lattice geometries providing important considerations for the structural integrity assessment of the components produced with the AM micro-lattices.