Quasi-static compression performance of multiphase 3D-printed PLA–PETG interpenetrating TPMS structures

Abstract

Triply Periodic Minimal Surface (TPMS) lattices are attractive cellular architectures owing to their smooth, curvature-continuous geometry, high surface-to-volume ratio, and efficient load-bearing behavior. TPMS structures are widely investigated for lightweight and energy-absorption applications, including impact-resistant protection systems and medical scaffolds. In this work, dual-nozzle fused deposition modeling (FDM) is employed to fabricate single-phase TPMS specimens from polylactic acid (PLA), while a complementary phase structure (CPS) is fabricated from polyethylene terephthalate glycol (PETG). The combination of these phases results in an interpenetrating phase composite (IPC). Four sheet-based TPMS topologies, namely Primitive, Gyroid, Diamond, and I-graph-wrapped package (IWP), are investigated. Quasi-static compression experiments are conducted to characterize and compare the compressive performance of the interpenetrating architectures and their constituent-phase counterparts. The results demonstrate that IPC architectures outperform the TPMS and CPS phases, revealing a strong synergistic effect induced by phase interpenetration. This structural synergy promotes more uniform deformation and mitigates strain localization. The IWP, Gyroid, and Primitive topologies exhibit the greatest improvements in stiffness, whereas the Primitive and Gyroid architectures achieve the highest yield stress and energy absorption capacity.