Topological effects of 3D-printed copolymer interlayers on toughening and in situ self-healing in laminated fiber-composites

Abstract

Interlaminar delamination in fiber-reinforced composites limits structural capacity and service life. Delaminations, which occur subsurface and can lead to catastrophic failures, are hard to detect and repair. Contrasting traditional mitigation strategies (e.g., inspection, over-design), proactive toughening and responsive self-healing of damaged interfaces offer practical, cost-effective solutions. Our recently developed strategy to address interlaminar damage—3D-printed thermoplastic interlayers and structurally integrated heaters—has been shown to achieve composite toughening and in situ self-healing via thermal remending, abetting repeated repair and improved delamination resistance. Here, we leverage this latest thermal remending strategy to investigate the effects of 3D-printed pattern topology on damage resistance and self-healing response. The chief attributes are: (i) realizing up to 450% increase in mode-I fracture resistance, (ii) restoring up to 100% of the increased fracture resistance for ten consecutive healing cycles, and (iii) achieving in situ self-healing below the thermoset-matrix glass transition temperature, thereby preserving structural integrity during repair. The proposed damage mitigation strategy fosters structural reliability, reduces failure risk, and increases service lifetime—three essential attributes in meeting the multifaceted demands of modern composite infrastructure.