Effects of a Vacancy Defect on Strength of Graphene Sheet and Carbon Nanotube

The presence of defects in a regular structure of graphene and carbon nanotubes (CNTs) can significantly influence their mechanical properties. In this work, the effect of an absence of a carbon atom (vacancy defect) on the strength of a graphene sheet and a single walled carbon nanotube (SWCNT) is studied using quasi static molecular dynamics (QSMD) simulations. Results show that a graphene sheet is more vulnerable to a vacancy defect compared to SWCNT. Reduction in ultimate tensile strength and strain due to the defect is comparatively small. Many researchers have used engineering strain as the strain measure for CNTs even though those structures experience higher strains. We use both engineering and true strains, and compare the effect of strain measure on the stress-strain relationships of CNT and graphene sheet.