Numerical analysis of 2D materials and its 3D form using nanoscale molecular dynamics (NAMD) simulation

Abstract

Single-layered and multi-layered graphene, together with mechanical properties and behavior were studied in this Final Year Project (FYP). This study aims to understand the differences in the mechanical properties and the in-plane deformation of carbon atoms for 3 types of graphene structures: monolayer graphene, AA-stacked multi-layered graphene (2-10 graphene layers), and AA-stacked graphite flake (>10 graphene layers). Nanoscale Molecular Dynamics (NAMD) Simulation was conducted using Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) via high performance computing services from Nanyang Technological University (NTU) High Performance Computing Centre (HPCC) to achieve the aim of this FYP. Evidence from NAMD simulation results has shown that monolayer graphene is a brittle material in nature. Interesting findings have been made when the monolayer graphene was loaded biaxially. It was found that the biaxial tensile strength in the y-direction is approximately 14.3% of the uniaxial tensile strength in that direction. Results obtained from the uniaxial tensile test also showed that all 3 types of graphene structures exhibit similar ultimate tensile strength (UTS) and young’s modulus. The 3 types of graphene structures were also observed to have similar in-plane mechanical behavior when the structures were stretched by 0.5Å in the plane of the graphene layers under triaxial loading conditions. Despite the monolayer graphene, AA-stacked multi-layered graphene and AA-stacked graphite flake having similar mechanical properties and behavior, it was noticed that there was also stress distribution across the different graphene layers for the different types of graphene structures. The overall conclusion from this FYP was that the mechanical properties and behavior of the 3 types of graphene structures were similar and insensitive to the number of graphene layers. Monolayer graphene exhibited similar mechanical properties and behavior to AA-stacked graphite flake.