Prediction of 3D elastic moduli and Poisson’s ratios of pillared graphene nanostructures

A computational finite element analysis based on a structural molecular mechanics approach was conducted to predict effective mechanical stiffness properties of a novel 3D carbon structure, pillared graphene structure (PGS), which is constituted with several graphene sheets and single-walled carbon nanotubes. Four sets of representative unitcell models were developed atomistically for predicting the mechanical properties of PGSs having different values of pillar length and inter-pillar distance. We introduced proper selections of the periodic geometry and boundary conditions which enabled our unitcell model to yield consistent results on the property prediction without any size or edge effects. The parametric study shows that the pillar length and inter-pillar distance significantly affect the effective in-plane and through-thickness properties. PGSs with shorter pillars in height yield higher planar Young’s and shear moduli, while those with smaller inter-pillar distance yield higher through-thickness moduli. Negative in-plane Poisson’s ratios are observed for all sets of PGSs and are associated with the curvature at the junction.