Shape memory alloys (SMAs) are a class of metallic alloys that possess remarkable characteristics such as superelasticity and shape memory effect. Superelastic SMAs have been considered as fiber in polymer composites due to their ability to recover their deformation upon removal of load, good energy dissipation capacity and impact resistance. Graphene nanoplatelets (GNPs) consists of small stacks of graphene sheets that are two-dimensional. Both sides of atomic lattice of GNPs contact matrix of a composite system and can generate more sites for potential chemical and physical bonding with the host material. Most importantly, graphene sheets and their derivatives can be produced at large-scale for industrial demand at low-cost.
This study explores the fabrication of multi-scale reinforced epoxy matrix composites in which GNPs and SMA strands are employed as nano- and micro-scale reinforcements, respectively. First, GNPs are dispersed into a ductile and brittle epoxy matrix to produce GNP/epoxy nanocomposites. To study the effect of GNP content on the behavior of the developed nanocomposite, GNPs are added to the epoxy-hardener mixture at different weight percentages (neat, 0.1%, 0.25%, 0.5%, 1%, and 2%). Uniaxial tensile tests of the developed nanocomposites are conducted under monotonic load up to failure. The optimum GNP content for GNP-reinforced epoxy matrix is determined and used in the fabrication of SMA fiber/epoxy composite. The developed multiscale reinforced epoxy composites are tested under tensile loading and their full-field strain and temperature behavior are monitored and evaluated using a digital image correlation system and an infrared thermal camera.