Bending behavior of uniform and graded TPMS wood-plastic composite sandwich beams

In this study, the effects of core topologies, relative density of the triply periodic minimal surface (TPMS) core, and graded relative density on the bending properties and energy absorption capacity of the TPMS wood-plastic composite sandwich structures were numerically investigated. The results indicated that, the sandwich structures with a Neovius core had better performance compared to other core topologies. With the relative density increasing from 15% to 30%, the bending stiffness of uniform sandwich structures with Primitive, Gyroid, and Neovius cores increased by 2.23, 1.17, and 2.71 times, respectively. Compared to uniform TPMS beams, graded structures showed decreased bending strength and toughness but increased bending stiffness. Based on these results, this paper proposed a method for calculating the bending stiffness of the graded sandwich structures. In this study, wood-plastic composite sandwich structures with a TPMS core exhibited higher bending stiffness and energy absorption than those with a traditional Honeycomb or Re-entrant honeycomb core. The calculation and test results indicated that TPMS sandwich structures can achieve ideal bending performance through graded design, and the calculation model can be used to select the best TPMS sandwich structure.