Anisotropic and tunable mechanical properties of graphene based asymmetric carbon honeycomb

• Anisotropic and tunable mechanical properties asymmetric carbon honeycombs (ACH) are constructed by controlling the asymmetric cell wall length and ratio. • A new continuum theoretical model is developed to predict the mechanical properties of ACHs accurately, while the famous Gibson-Ashby model is failure to calculate the mechanical features of ACHs. • Revealed the correlation between micro-structure and mechanical performance. • A wide range of stiffness, strength and specific energy absorption capacity can be obtained by introducing anisotropy. • Stress concentration is founded as the key physical influence factor of the cell-size dependent strength of ACH. Graphene based three-dimensional carbon honeycomb has attracted enormous attentions due to its excellent physical properties and wide application promises. Based on atomistic simulations, we reveal that asymmetric carbon honeycombs (ACHs) under in-plane tension display anisotropic and tunable mechanical behaviors dependent of the honeycomb cell size. E.g., the Young's modulus (fracture stress) of ACHs in one direction are around 160.0 (29.0) GPa, while decreases from 157.3 to 5.1 (31.52 to 1.87) GP in the other direction. They show ∼31 (15.5) times anisotropic difference, and ∼30 (16.8) times tunable for the Young's modulus (fracture stress). These cell-size dependent features cannot be predicted by the widely used Gibson-Ashby continuum honeycombs model, and a new continuum theoretical model is developed to predict the results accurately. Under compression, ACHs can provide broad range options specific energy absorption capacity, e.g., from 11665.7 to 388.5 MJ/m 3 . The present study reveals key structure-property relationships of ACHs under in-plane and out-of-plane tension/compression. Our results provide a useful guideline for the rational design of graphene based honeycomb structures with targeted properties for practical engineering application.