Strain dependent elastic modulus of graphene

TL;DR

This study demonstrates that the elastic modulus of graphene increases significantly with pre-strain due to anharmonic effects and out-of-plane corrugations, suggesting the true in-plane modulus is higher than previously thought.

Contribution

It provides experimental evidence that graphene's elastic modulus depends on strain and corrugations, challenging the accepted value of 340 N/m.

Findings

Elastic modulus increases from 300 N/m to 700 N/m with pre-strain.

Out-of-plane corrugations significantly influence measured stiffness.

The in-plane elastic modulus is closer to 700 N/m, not 340 N/m.

Abstract

Indentation experiments on graphene membranes pre-stressed by hydrostatic pressure show an increase in effective elastic modulus from 300 N/m in non pressurized membranes to 700 N/m for pre-strains above 0.5 %. This pronounced dependence of the stiffness of graphene with strain is attributed to its high anharmonicity and the great influence of out of plane corrugations of this atomic thick membrane in its mechanical properties. Our experimental findings imply that graphene measured stiffness is highly influenced by the presence of corrugations and that the in plane elastic modulus corresponding to atomic bond stretching is more akin to 700 N/m, instead of the commonly accepted 340 N/m.