Effect of Drilling-Induced Delamination on the Flexural Strength of GNPs-Reinforced Carbon Fiber Sandwich Composites

In this study, the effect of drilling-induced delamination damage on the flexural strength of sandwich composites with 0.5% by weight GNPs (graphene nanoplatelets) reinforced carbon fiber face sheets (GNPs/carbon sandwich) and nanoparticle-free Neat/carbon sandwich composites was investigated. In three-point bending specimens, drilling operations were performed with hole diameters of 5 mm and 6 mm. Delamination damage at the entry and exit points of the holes were observed through microscopic imaging and evaluated. Image processing techniques were applied to microscopic images, and quantitative values were obtained. According to the three-point bending test results, the lowest strength loss was observed in GNP/carbon sandwich composites. The highest bending strength was measured as 800 N in GNP/carbon sandwich composites. The lowest bending strength was found to be 450 N in pure/carbon sandwich composites drilled with a 6 mm diameter hole. Adding GNPs nanoparticles to carbon fiber sandwich composites reduced delamination damage caused by drilling. GNPs-reinforced sandwich composites showed better bending strength compared to sandwich composites without nanoparticles.