Exploring fillet radius effects in 3D-printed Schwarz Triple Periodic Minimal Surface (TPMS) structures: experimental validation and FEM insights

Triply Periodic Minimal Surface (TPMS) structures, such as the Schwarz configuration, offer exceptional mechanical performance due to their periodic, continuous, and highly interconnected geometry. This study systematically investigates the effects of lattice parameter and wall thickness on the compressive behavior of Schwarz Primitive TPMS structures. High-resolution digital light processing (DLP) additive manufacturing was employed to fabricate the structures, and experimental compression tests were conducted alongside finite element simulations for validation. Results indicate that smaller lattice parameters improve the uniformity of stress and plastic strain distribution, further increasing energy absorption. As a novel application, these findings demonstrate that Schwarz TPMS structures can serve as internal energy-absorbing layers in bicycle helmets, where optimized thickness and lattice size provide higher load-bearing capacity, controlled plastic deformation, and superior impact mitigation, all while maintaining lightweight construction and ventilation. In particular, increasing wall thickness from 0.5 to 1 mm for a lattice parameter of 8 mm significantly enhances mechanical properties, with maximum compressive force rising from 2143.7 to 9378 N, specific stiffness from 235.7 to 323 N/mm·g, and specific energy absorption from 1542.1 to 2285.1 mJ/g. This work establishes a quantitative framework for tailoring TPMS geometry to enhance mechanical performance in protective gear applications.