Effect of chirality and defects on tensile behavior of carbon nanotubes and graphene: Insights from molecular dynamics

D Bedi and S Sharma and SK Tiwari, DIAMOND AND RELATED MATERIALS, 121, 108769 (2022).

DOI: 10.1016/j.diamond.2021.108769

Molecular dynamic simulations based on AIREBO potential function with Nose-Hover thermostat technique have been performed in this study to predict the mechanical properties of pristine as well as defective graphene and carbon nanotubes (CNTs). The effect of structural defects such as point defects (PD) and Stone-Wales (SW) defects on the stress- strain distribution and ultimate strength have been explored under uniaxial tension. The simulations revealed that the defects decrease the strength of graphene sheets and CNTs. Both the strength and failure strain were found to decrease with an increase in the number of defects. The tensile strength was found to be halved on loading the graphene in the armchair direction as compared to loading in the zig-zag direction due to the extension of the carbon-carbon bond in the armchair loading direction. The fracture strength of the pristine zigzag graphene sheet is higher than for the pristine armchair graphene sheet in case of uniaxial tensile loading. The failure strain of the zigzag graphene sheet is higher than the armchair graphene sheet. PDs have a greater impact on the degradation of strength of nanostructure than the SW defects. The higher the number of defects, the lower is the strength of the nanostructure.

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