Mechanical Properties of Graphene Papers

TL;DR

This paper investigates the mechanical properties of graphene papers by combining first-principles calculations and continuum modeling, revealing a characteristic length scale and proposing a deformable tension-shear model for better predictions of their mechanical behavior.

Contribution

It introduces a deformable tension-shear model that accounts for elastic deformation in graphene sheets and crosslinks, improving upon traditional models for large-scale graphene-based materials.

Findings

Identification of a characteristic length scale l_{0} for graphene sheets.

Failure of traditional tension-shear models beyond 3l_{0} size.

Development of a deformable tension-shear (DTS) model for accurate predictions.

Abstract

Graphene-based papers attract particular interests recently owing to their outstanding properties, the key of which is their layer-by-layer hierarchical structures similar to the biomaterials such as bone, teeth and nacre, combining intralayer strong sp2 bonds and interlayer crosslinks for efficient load transfer. Here we firstly study the mechanical properties of various interlayer and intralayer crosslinks via first-principles calculations and then perform continuum model analysis for the overall mechanical properties of graphene-based papers. We find that there is a characteristic length scale l_{0}, defined as \Sqrt{Dh_{0}/4G}, where D is the stiffness of the graphene sheet, h_{0} and G are the height of interlayer crosslink and shear modulus respectively. When the size of the graphene sheets exceeds 3l_{0}, the tension-shear (TS) chain model that are widely used for nanocomposites fails to predict the overall mechanical properties of the graphene-based papers. Instead we proposed here a deformable tension-shear (DTS) model by considering the elastic deformation of the graphene sheets, also the interlayer and intralayer crosslinks. The DTS is then applied to predict the mechanics of graphene-based paper materials under tensile loading. According to the results we thus obtain, optimal design strategies are provided for designing graphene papers with ultrahigh stiffness, strength and toughness.