Understanding the mechanical properties and deformation behavior of 3-D graphene-carbon nanotube structures

Here, a new three-dimensional graphene-carbon nanotube (3-D GR-CNT) structure was proposed, and the compressive mechanical properties and deformation behavior of the 3-D GR-CNT structure were evaluated using molecular dynamics (MD) simulations. It was found that the 3-D GR-CNT structure had outstanding mechanical properties, especially the ultrahigh Young's modulus, which was up to 1018 GPa and as high as that of GR. The 3-D GR-CNT structure did not have plastic deformation during the compression. The effects of GR length and CNT diameter were evaluated, and it was demonstrated that when the ratio of CNT diameter to GR length was about 0.6, the ultimate stress of the 3-D GR-CNT structure was the highest. Owing to the low density of the 3-D GR-CNT structure, the structure had outstanding specific strength. At a small compressive deformation, GRs produced buckling deformation with wrinkles to resist compression. After reaching the critical buckling stress, CNTs began to produce wrinkles; and after reaching the failure stress, the destruction started from the junctions. In addition, compared with the sp(3) carbon atoms, the sp(2) carbon atoms were more suitable for the junctions, as more energy could be absorbed by the sp(2) carbon atoms in the junctions. (C) 2018 Elsevier Ltd.