Topology Optimization Design of TPMS Structures Based on Element Principal Stress Directions

Triply periodic minimal surface (TPMS) structures are lightweight with high strength, favorable vibration attenuation, and energy absorption, showing broad application prospects in aerospace, biomedical, and automotive industries. Existing topology optimization research mainly addresses mechanical limitations of single‐type TPMS unit cells but ignores metallic plasticity and material damage in numerical modeling. This work develops a density‐gradient hybrid optimization method for TPMS structures. Plastic responses of Al–Si 10 –Mg are integrated into the classical solid isotropic material with the penalization (SIMP) model for secondary density regulation of unit cells. Using homogenization and representative volume element (RVE) approaches, a mechanical property database is built for Primitive (P), Gyroid (G), I‐wrapped package (IWP) and F‐rhombic dodecahedra (FRD) TPMS unit cells. Guided by the principal stress direction under external loading, these four unit cells are rationally arranged and hybridized to improve beam stiffness. Results reveal that the plastic‐aware optimized structure achieves 9.94% higher stiffness than conventional topology‐optimized designs. The optimized TPMS beam delivers 49.55% stiffness gain over uniform P‐type beams in four‐point bending and 49.33% improvement for cantilever beams. This method demonstrates promising engineering application potential.