Static and fatigue performance of graphene nanoplatelets coated bi‐directional carbon fiber‐epoxy composites under bending loads

The addition of graphene nanoplatelets as a nanofiller on the surface of pristine and oxidized carbon fiber for making reinforced polymer composites has shown improvement in monotonic flexural properties. However, the fatigue response of these laminates under bending loads has not been investigated so far. The current study aims to examine the monotonic and fatigue behavior of the graphene nanoplatelets (GNPs) coated bi‐directional pristine and oxidized carbon fiber epoxy composites under bending loads. Eight layers of fabrics were used to manufacture the laminates through vacuum‐assisted resin transfer molding technique (VARTM). An optimum amount of GNP addition on oxidized fiber leads to ~830‐fold enhanced fatigue life at higher stresses as compared to pristine laminates. However, excessive GNP addition on pristine as well as oxidized fiber leads to a deterioration in fatigue life. In‐situ optical microscopic examination was done to observe the crack initiation and propagation of all the specimens with respect to the number of cycles coupled with post‐mortem SEM images of the fracture surfaces.