The mechanical performance of functionally graded Schwarz primitive and Schoen-IWP cellular structures fabricated by additive manufacturing

Additive manufacturing has the capability of fabricating structures with customized or complex architecture. One of the major advantages of additive manufacturing is the ability to fabricate functionally graded materials with the controlled internal architecture of structures that can be strategically used in enhanced absorption of energy. The current study investigates the mechanical performance of graded triply periodic minimal surfaces (TPMS) fabricated by masked stereolithography (MSLA) additive manufacturing technique. Samples of Schwarz primitive and Schoen-IWP structures with graded and uniform relative density were designed and manufactured. Sample morphology, deformation behavior, and mechanical characteristic were investigated. The graded structures deformed from the layer with the thinnest wall thickness to the layer with the thickest wall in a progressive layer-by-layer approach. In contrast, uniform structures showed complete diagonal shear failure. The total energy absorption to the densification point was 0.45 MJ/m3 and 0.198 MJ/m3 for graded and uniform Schwarz primitive structures, respectively. Additionally, the absorbed energy of the graded Schoen-IWP structure was 0.58 MJ/m3 while the uniform one absorbed 0.889 MJ/m3.