Design, fabrication, and evaluation of functionally graded triply periodic minimal surface structures fabricated by 3D printing

Cellular structures are a favorite selection for the design of lightweight components and energy absorption applications due to several advantages such as their customizable stiffness and strength. In this investigation, functionally graded (FG) triply periodic minimal surfaces, Schoen-IWP (SIWP), and Schwarz primitive (SPrim) cellular structures were fabricated by masked stereolithography (MSLA) technique using ABS-like gray resin. The sample morphology, deformation behavior, mechanical characteristics, and energy absorption of graded and uniform structures were studied using experimental compression tests. The FG sample structures exhibited layer-by-layer collapse delaying shear failure. On the other hand, uniform samples showed complete diagonal shear failure. The total energy absorption to the densification point was 0.52 MJ/m3 and 0.58 MJ/m3 for graded and uniform SIWP, respectively. Additionally, the absorbed energy of the graded SPrim structure was 0.59 MJ/m3 while the uniform one absorbed 0.27 MJ/m3. The investigations showed that the graded SPrim absorbed more energy with high densification strain during the compression test.