Fracture mechanisms and normalized compressive response of a TPMS-based PLA-CF/silicone/graphene oxide interpenetrating phase composite

Interpenetrating phase composites (IPCs) based on architected lattice structures provide an effective strategy for enhancing mechanical performance through synergistic interaction between geometry and material phases. In this study, a novel IPC system was developed by infiltrating additively manufactured triply periodic minimal surface (TPMS) lattices with a graphene oxide (GO)-modified silicone matrix. Primitive TPMS lattices were fabricated using fused deposition modeling with carbon fiber-reinforced polylactic acid (PLA-CF) filament, followed by a mold-based infiltration process to form fully continuous interpenetrating architectures. Uniaxial compression tests were conducted in accordance with ISO 13314 at different strain rates to evaluate force-displacement behavior, engineering stress-strain response, and normalized stress-strain characteristics. The IPC specimens exhibited a distinct three-stage deformation behavior consisting of initial elastic lattice engagement, progressive collapse, and densification-controlled deformation. Compared to matrix-only systems, the IPCs demonstrated significantly enhanced load-bearing capacity, stable plateau behavior, and improved normalized stress retention. Increasing strain rate resulted in higher peak stress and delayed softening, reflecting the strain-rate-sensitive response of the silicone-GO matrix and its interaction with the TPMS lattice. Normalized stress analysis, obtained by scaling stress with respect to the maximum stress, enabled direct comparison of deformation efficiency across different testing conditions. Fracture mechanisms were investigated using post-mortem scanning electron microscopy, revealing progressive damage evolution involving strut bending, controlled strut fracture, interfacial bonding, crack deflection, and matrix-assisted crack bridging. The presence of graphene oxide promoted rough fracture surfaces and enhanced energy dissipation, effectively suppressing catastrophic failure. These results demonstrate that TPMS-based IPCs with GO-modified silicone matrices offer improved damage tolerance and stable compressive performance, highlighting their potential for energy-absorbing and load-bearing applications.