Anisotropic and tunable mechanical properties of graphene based asymmetric carbon honeycomb

Abstract

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 11,665.7 to 388.5 MJ/m3. 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.

Keywords

• Anisotropic mechanical properties
• Tunable mechanical properties
• Asymmetric carbon honeycomb
• Energy absorption