Tensile Mechanical Properties Study Of Monolayer Graphene Nanoribbons Based On Molecular Dynamics

Graphene is a one-atom-thick planar sheet of sp2-bonded carbon atoms that aredensely packed in a honeycomb crystal lattice. With excellent mechanical, thermal,electrical properties, it is expected to play an important role in the field ofnano-mechanical and electronic (NMES), nano-electronics and nano-composites.Therefore, the study of graphene’ mechanical properties is very important.Firstly, the molecular dynamics method was used to study the relaxationcharacteristics and tensile mechanical properties of monolayer graphene nanoribbons byLAMMPS software. Secondly, the simulations were conducted to the temperature,strain ratio and size dependences. Finally, the influences of vacancy defects andStone-Wales defects on monolayer graphene nanoribbons were researched using MDsimulation.The fracture progress of monolayer graphene nanoribbons under tension wasinvestigated using the REBO potential function. The Young’ modulus of Armchair andZigzag nanoribbons at300K are determined, which are0.931TPa and0.848TPa,respectively. The data is consistent with previous data published in literature. TheYoung’ modulus of both chiral graphene nanoribbons slightly decrease withtemperature rising, while the critical strain and tensile strength value drop significantly.When the temperature rising from0.01K to2400K, the Young’ modulus of both chiralgraphene nanoribbon fall by27.3%and21.4%. The Young’ modulus is insensitive tostrain ratio and roughly between0.82~0.95TPa when strain ratio ranges from1×108s-1to1×1011s-1. When the strain ratio is higher than5×109s-1, the graphene nanoribbonsapparently experiences a hardening process and the tensile strength increasessignificantly. For rectangular graphene nanoribbons, the Young’ modulus reduces as thenanoribbons width reduces and approaches that of bulk graphene. However, for squaregrapheme nanoribbons, the Young’ modulus slightly decreases with the width ofnanoribbons increasing and slowly converges to the Young’ modulus of bulk graphenein the case of the length exceeding8nm. Vacancy defects and Stone-Wales defects notonly deteriorate the mechanical properties, but also change the fracture mechanism ofmonolayer graphene nanoribbons.