Mechanical properties of graphene nanoplatelets containing random structural defects

Graphene nanoplatelets (GNPs) consist of a small number of graphene sheets connected through van der Waals forces and, like graphene, offer exceptional mechanical, thermal and electric properties. In this work, GNPs are considered as potential reinforcements in composites and their equivalent mechanical properties are computed. Similarly to graphene, the mechanical behavior of GNPs is greatly affected by the presence of structural defects and therefore, a parametric investigation is conducted herein. Three types of planar defects are considered: Stone-Wales, single vacancy and double vacancy defects. The examined parameters include the defect type, density, distribution as well as the number of graphene layers. The Molecular Structural Mechanics approach is employed to simulate the lattice of each graphene sheet, where the C-C covalent bonds are modeled by energetically equivalent beam elements. The van der Waals interactions between two carbon atoms belonging to different graphene sheets are modeled using truss elements with mechanical properties based on Lennard-Jones potential. Equivalent properties are computed by employing a homogenization-like procedure and random fields of the stiffness tensor are obtained through the moving window technique. A severe reduction of the stiffness of GNPs is observed for vacancy defects, which also lead to considerable variability. Inplane behavior, which differs greatly from out of plane behavior, is shown to be much more susceptible to the effect of defects.

Automated summary

In this work, the mechanical behavior of graphene nanoplatelets (GNPs) with different planar defects is investigated. The stiffness of GNPs is severely reduced by vacancy defects, leading to significant variability. Inplane behavior is more susceptible to the effect of defects compared to out of plane behavior.