The Effect of Crack Orientation on the Propagation of Cracks in Graphene Nanoplatelet Carbon Fiber-reinforced Epoxy Composites Using Digital Image Correlation

This study experimentally investigated the fracture behaviors of graphene nanoplatelet (GNP) carbon fiber-reinforced polymer (CFRP) composites for varying amounts of GNP reinforcement, crack lengths and crack orientation angles. The specimens were subjected to tensile loading, and their fracture toughness values were determined with respect to maximum damage load and crack length. To compare the results obtained from experimental data, the fracture toughness values, strain distributions and crack tip opening displacements were determined by using a Digital Image Correlation (DIC) technique from images recorded during the tests. The results showed that increasing the amount of GNP increased the fracture toughness of specimens. On the other hand, increasing the crack orientation angle decreased the fracture toughness. Increasing the crack length increased the fracture toughness values for a crack orientation angle of 30 degrees but decreased for a crack orientation angle of 90 degrees. DIC results were found to be compatible with the calculated results using crack length and damage stress values.