▎ 摘　　要

Graphene assembly, e.g. graphene aerogel, is an open-cell porous material with randomly distributed graphene sheets and voids. In this study, we propose a method to generate the 3D graphene assembly models which can reasonably display the structural properties of graphene aerogel. Our 3D graphene assembly models are firstly established by a Voronoi construction method that is usually used to build the polycrystalline materials. The optimization and relaxation are then conducted to obtain 3D graphene assembly with proper structures by using molecular dynamics (MD) simulations. In order to explore the mechanical properties of graphene assembly, the tensile and compressive tests are carried out by MD simulations. The results show that the 3D graphene assembly reveals auxetic behavior under compression while it has positive Poisson's ratio under tension. We also find that the Poisson's ratios are specifically related to the grain sizes and mass densities. Furthermore, from our simulation the stress-strain relations for the compressive tests and tensile tests are also obtained. The compressive Young's modulus, tensile Young's modulus, compressive strength and tensile strength are found to follow the power law relation to the mass density with the exponential factors of 2.31756, 2.33005, 2.6243 and 1.5084, respectively.