Theoretical analysis of high strength and anti-buckling of three- dimensional carbon honeycombs under shear loading

S Zhang and YB Zhu and FC Wang and XY Liu and HA Wu and SN Luo, COMPOSITES PART B-ENGINEERING, 219, 108967 (2021).

DOI: 10.1016/j.compositesb.2021.108967

Three-dimensional carbon honeycombs (3D C-honeycombs) are considered as a promising matrix material for new composites, while their mechanical behaviors under complex stress status remain unclear. Here, shear response of 3D C-honeycombs is systematically investigated with molecular dynamics (MD) simulations and mechanical analysis. Two deformation modes are observed for 3D C-honeycombs under in-plane and out-of-plane shear loading. A mechanical model is proposed to describe the deformation of 3D C-honeycombs under different shear loading, and agrees well with the MD simulations. Under in-plane shear loading, the initial elastic deformation is dominated by distortion of hexagon structures, shear modulus increases as increasing shear strain, and the tension of side walls leads to fracture. Under out-of-plane shear loading, the structure of 3D C-honeycombs can remain stable until fracture regardless of side wall buckling, and the tensile stress concentration at junctions gives rise to fracture. For both the two modes, the junction type has a negligible effect on shear strength of 3D C-honeycombs. The stability of junctions plays a dominant role in the shear response of 3D C-honeycombs, and thus the superb mechanical properties of graphene can be largely inherited by the 3D C-honeycombs.

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