Evaluation of graphene nanoplatelets addition and machining methods on the hole quality and bearing strength of glass and carbon fibre reinforced epoxy laminates

In this work, a conventional floor fitted (CFF) drilling machine and abrasive waterjet (AWJ) machine are used to drill the holes of diameter 10 mm in the glass fibre/epoxy (GFRP), carbon fibre/epoxy (CFRP), graphene nanoplatelets/glass fibre/epoxy (GNP/GFRP), and graphene nanoplatelets/carbon fibre/epoxy (GNP/CFRP) laminates. Then, the drilled specimens are subjected to a double shear bearing test under tensile loading at 1 mm/min. The GNP/CFRP laminates drilled with the CFF drilling machine containing 0.125 wt% and 0.25 wt% of graphene nanoplatelets exhibited 13 % and 23 % higher peak load, while those drilled with AWJ machine showed 7 % and 17 % higher peak load compared to CFRP laminates, respectively. Similarly, the GFRP laminates drilled with the CFF drilling machine containing 0.125 wt% and 0.25 wt% of graphene nanoplatelets showed 6 % and 10 % higher peak load, while those drilled with AWJ machine showed 9 % and 19 % higher peak load compared to GFRP laminates, respectively. It is evident from the results that the addition of graphene nanoplatelets increased the bearing strength of both GFRP and CFRP composite laminates, irrespective of the machining process adopted for drilling holes. Overall, AWJ machining is better suited for drilling holes in GFRP and CFRP laminates than the CFF drilling technique.