Structural Integrity of Metamaterials Fabricated by Additive Manufacturing
Abstract
Additive Manufacturing (AM) or 3D printing, represents a revolutionary shift in production technology by enabling the construction of complex geometries that were previously infeasible with traditional manufacturing methods. This technology layers material to form objects from 3D model data, usually layer by layer, as opposed to subtractive manufacturing methodologies. The distinctiveness of AM comes from its ability to produce customized and complex structures that significantly optimize material usage and functional design.
With a focus on metamaterials, this thesis aims to investigate the associations between the geometry of these structures and their mechanical properties when fabricating with AM technologies. Specifically, the impact of geometrical factors such as build thickness, scale, and unit cell arrangement, on the printing quality of polymeric and metallic metamaterials is explored. The consequent impact of the process variation due to the geometrical change on the mechanical performance of the printed structures is investigated under quasi-static and fatigue loading conditions. Overall, the PhD work is aimed at providing a better understanding of the root cause of geometrical inaccuracies and deviation in mechanical properties of components with different scales, which can then help for enhanced AM design procedures, quality assurance, and process optimization strategies.
The appended papers represent the main contribution of this thesis. The main method of study employs assessment of geometrical deviations, internal defects, surface topography, microstructural investigation, mechanical testing of AM lattice structures under quasi-static and fatigue loading conditions, failure assessment and fractography of the tested specimens and ultimately the use of numerical modelling for evaluation of the deformation mechanisms and fracture in the tested specimens.