Effect of nitrogen-doped reduced graphene oxide on buckling and post-buckling behavior of layered CFRP composites with embedded delamination

Delamination is a critical failure mechanism in composite materials, significantly reducing their structural integrity and load-bearing capacity. This study examines the buckling and post-buckling behavior of CFRP composites reinforced with nitrogen-doped reduced graphene oxide nanoparticles (ND-RGOP) and the effects of embedded delamination length. Composites with varying delamination lengths were subjected to static compression tests, complemented by cohesive zone modeling to simulate delamination behavior. Results indicate that a small embedded delamination (25 mm) reduces the critical local buckling load by 63.9%, inducing a shift from global to local buckling, while larger delaminations (75 mm) decrease the critical load by over 90%. The addition of 0.4% ND-RGOP enhances the critical buckling load by more than 20%, attributed to improved matrix-fiber interactions, as observed in FESEM analysis. Laminates with small embedded delaminations show rapid and unstable delamination growth, while larger embedded delaminations lead to slower and more stable delamination growth. Furthermore, ND-RGOP addition reduces delamination growth rates by over 10%. These findings highlight the potential of ND-RGOP reinforcement to improve buckling resistance and slow delamination in composites.