Investigation on graphene addition on the quasi-static and dynamic responses of carbon fibre-reinforced metal laminates

In this paper, graphene nanoplatelets (GnPs) were used with carbon fibre/epoxy composite to enhance the mechanical performance of fibre metal laminates (FMLs). The designed FMLs are composed of thin aluminium alloy layers alternating with carbon-fibre epoxy/GnP composite plies with a chemical treatment performed on the aluminium laminate to promote adhesion strength with the epoxy composite. Two different configurations of FMLs were investigated (i) composite plies with unidirectional carbon fibres (U-FMLs) and (ii) composite plies with plain carbon woven (W-FMLs). Samples were tested under dynamic loading (Charpy impact) and quasi-static loading (three-point flexure). The experimental results showed that FMLs with 0.3 wt% GnPs logged the best impact performance; the impact strength of W-FMLs and U-FMLs are respectively 18.2% and 25.2% higher than FMLs without GnPs. FMLs with 0.5 wt% GnPs recorded the highest enhancement in flexural strength, fracture strain and flexural modulus recording increments 23.1%, 19.3% and 48% for the W-FMLs, and 60.3%, 34.5% and 61.4% for the U-FMLs, respectively. Also, an in-depth microscopic analysis was conducted to understand the reinforcing mechanism of GnPs into FMLs. Moreover, a numerical model of a three-point flexural test was developed to show the ability of numerical tools to predict material behaviour at optimized costs. Johnson-Cook and Hashin damage models were used respectively for aluminium alloy and carbon fibre epoxy/GnP composite to accurately predict their deformation and damage modes.