The Influence of Vacancy Defects on The Young’s Modulus of Graphene Sheets

The main objective of this research is to study the degree to which vacancy defect can reduce the Young s modulus of a graphene sheet. Among different modeling techniques, semi-continuum modeling wherein carbon-carbon bonds are replaced with continuum element is chosen. For this purpose, two different finite element models employing beam and spring elements are constructed. Then, the vacancy defect is incorporated into the model by removing carbon atom(s). Both locations and number of defects are taken into account as random parameters, thus stochastic analysis is implemented. A computer code is provided for stochastic modeling generating sufficient number of samples. A convergence criterion is defined and convergence study is performed to extract sufficient numbers of realizations for each case of defect density. For each case, both average and standard deviation of Young s modulus are reported. A decreasing trend of Young s modulus versus defect density is reported and discussed reported implying on the important role of vacancy defect. Topology of defects distribution is also studied addressing both lower and higher levels of reduction. Finally, a comparison is performed to analyze the influence of beam-based and spring-based model on the results.

Keywords:

Graphene , Defect , Finite modeling , Spring element , Beam element , Young’s modulus