Effects of graphene nanoplatelets on the lightning strike damage response of carbon fiber epoxy composite laminates

With the increasing use of carbon fiber epoxy composite materials in the aerospace and wind energy industries, protecting these composite structures from lightning strike has become a vital and challenging task. Conventional lightning protection of carbon fiber composites requires the use of a surface layer of expanded metal mesh film. Such solution has shown disadvantages including (i) additional weight and cost and (ii) debonding between the mesh film and the composite laminate due to environmental aging. An alternative solution is adding lightweight conductive additives to epoxy resin instead of using heavy metal mesh. In this paper, we investigated effects of premixing highly conductive graphene nanoplatelets with epoxy resin on the overall electrical resistance and lightning damage response of composite laminates. Four carbon fiber composite laminate panels were fabricated using hand-layup followed by hot pressing, including two baseline panels without graphene nanoplatelets, two other panels with 0.5 and 1.0 wt. % graphene nanoplatelets, respectively. The quasi-isotropic composite laminates were subjected to simulated lightning strikes with 100 kA impulse current. Both visual observation and ultrasonic inspection were carried out to identify the lightning strike damage and characterize the role of graphene nanoplatelets in mitigating lightning strike damage. Our results indicate that adding nanographene platelets significantly decreases the surface electrical resistance of the composite laminate and reduces the severity of the lightning strike damage.