In-situ synchrotron X-ray tomography investigation of micro lattice manufactured with the projection micro-stereolithography (PμSL) 3D printing technique: Defects characterization and in-situ shear test

The robust mechanical properties of architected micro lattice mechanical metamaterials are determined by their precisely designed artificial microstructures, and various types of mechanical metamaterials have been proposed for acoustic manipulation, impact energy absorption, vibration attenuation, etc. In this paper, 3D pyramid and hourglass micro lattice samples are fabricated with projection micro-stereolithography (PμSL) 3D printing technique. Synchrotron X-ray tomography 3D imaging at the sub-micrometer precision level is employed for characterizing surface roughness and internal void defects distribution induced by the manufacturing process. Afterwards, synchrotron X-ray tomography 3D imaging of the in-situ shearing deformation process is performed for studying the failure process and deformation modes of the as-fabricated micro-lattice samples. It is found that manufacturing surface roughness and internal defects within the lattice beams and nodes can significantly influence the deformation behaviors and failure modes of these shearing micro lattice samples. Finally, three types of finite elementanalysis (FEA) models based on synchrotron X-ray tomography 3D image reconstruction are proposed for understanding the relation between manufacturing defects and mechanical behaviors of micro lattices, where effects of statistical distributions of geometry defects of micro lattice structures are focused. Based on comparison between experimental and numerical results, it can be concluded that manufacturing defects can change the deformation behaviors and mechanical integrity of micro-lattice remarkably.