Dynamic properties and toughening mechanisms of GNPs reinforced carbon fibers/epoxy textile composites under an SHPB impact load

In the recent years, the mechanical and damping properties of fiber reinforced polymer composites have been improved by the addition of nanofillers such as titanium oxide, alumina oxide, carbon nanotube, and nanoclay. Recently, graphene nanoplatelets (GNPs) due to its exceptional characteristics, is getting significant attention. The literature that is currently available shows that adding graphene nanoplatelets can improve the stiffness, strength, and fracture toughness of fiber reinforced polymer composites when they are subjected to static and quasi-static loadings. However, there is currently a lack of information regarding how the incorporation of graphene nanoplatelets (GNPs) to the epoxy matrix can affect the dynamic response of carbon-epoxy composites, such as dynamic stress-strain behavior, stiffness, strength, and damage kinetics. The aim of this study is to examine the dynamic behavior of a composite made of carbon fibers and epoxy matrix filled with different mass fractions (0% as a reference, 0.5%, 1%, and 2%) of GNPs using Split Hopkinson Pressure Bar (SHPB). When compared to the findings obtained with carbon fiber reinforced polymer (CFRP) composites, the experimental results showed that adding up to 1% of GNPs resulted in significant improvements in strength and stiffness as well as decreases in delaminated area. However, a further increase in the mass fraction of GNPs in the epoxy matrix could lead to the presence of agglomerations and the non-uniform distribution of the filled resin between the carbon fibers, resulting in weak interfacial bonding, reducing the performance of the final composite, and leading to delamination failure.