Experimental study on the fracture behavior of 3D printed interpenetrating phase composites with triply periodic minimal surface architectures

Interpenetrating phase composites (IPCs) reinforced with triply periodic minimal surface (TPMS) architectures have garnered widespread attention due to their excellent mechanical properties under compression. Nonetheless, research into the fracture behavior of TPMS-based IPCs under flexural loading remains relatively limited, and their fracture mechanisms still require clarification. Herein, IPCs with different TPMS configurations and material systems were fabricated by multi-material additive manufacturing. Subsequently, quasi-static three-point bending tests were performed on single-edge notched bend (SENB) specimens of these IPCs to investigate their fracture behavior. The strain field evolution within the specimens during the loading process was determined by digital image correlation (DIC) analysis, and microscopic observations were conducted on the fracture morphologies of the specimens to reveal their fracture mechanisms. Accordingly, the fracture toughness and energy absorption capabilities of different TPMS-based IPCs were evaluated. The results indicated that the reinforced TPMS structure activated toughening mechanisms in the IPCs during deformation, inhibiting crack propagation and leading to significant crack deflection/torsion, which contributed to the enhancement of the material toughness. The VB+/Agilus30 system outperformed VB+/PP due to the superior ductility of Agilus30, while the IWP-IPCs exhibited higher J-integrals and energy absorption than the Diamond-IPCs. Furthermore, when compared to traditional lattice-based IPCs, TPMS-based IPCs demonstrated superior fracture resistance. This research may provide valuable insights for modulating the fracture properties of IPCs by tailoring the reinforcement topology and constituent material properties.