A multiscale modeling on fracture and strength of graphene platelets reinforced epoxy

Abstract A novel multiscale simulation framework was proposed to investigate the mechanical properties of single layer graphene platelets reinforced crosslinked epoxy. Crosslinking reactions in composites were simulated with the molecular dynamics (MD) method in the nanoscale, and the mechanical properties of bulk epoxy and interfaces between unfunctionalized graphene and epoxy were obtained. These mechanical properties from MD method were used in FEM simulation in the microscale. The crack propagation in composites was investigated with the finite element method (FEM) based phase-field method (PFM). The influence of several morphologic factors of graphene platelets on mechanical properties, including volume fractions, distributions of graphene orientations and waviness of graphene, was investigated. Results showed that the increasing graphene volume fraction would lead to the decrease of mechanical properties of composites due to the weak interfacial strength in the present model. Meanwhile, aligned graphene platelets improve all the mechanical properties simultaneously. In addition, the graphene platelets with higher curvatures provide improvement of the overall mechanical properties of the composites because they can block interfacial sliding. The present research suggested that the interfacial strength can be the bottleneck in the graphene reinforced epoxy.