Effect of temperature and strain-rate on mechanical properties of defected graphene sheet: A molecular dynamics study

Graphene, a one atom thick sheet of carbon exhibits outstanding mechanical properties, but defects which are unavoidable at the time of synthesis may strongly affect, such as intrinsic properties and fracture toughness of graphene can be altered by topological defects such as vacancy, Stone-Thrower-Wales (STW) defects, dislocations and grain boundaries. In this research article, authors have extensively studied the effect of Stone-Thrower-Wales defect on mechanical properties of a single layer of graphene sheet at different temperature and strain-rates using classical molecular dynamics (MD) based simulations. Also, authors have studied the effect of defect-concentration on the mechanical properties of graphene at different temperature and strain rates. It has been observed that fracture strength and strain is not varying with temperature for STW-1 in zigzag direction and STW-2 in armchair direction respectively. Also, the same scenario was observed for different strain-rate values. Further-more it was observed that at 1K both STW-1 and STW-2 defects shows almost same fracture strength and strain in armchair and zigzag directions for higher strain-rates. On the other hand, at lower strain-rates both STW-1 and STW-2 defects showed different fracture strength and strain at 1K. Also, it was observed that at higher temperatures STW-1 in armchair direction and STW-2 in zigzag direction shows enormous decrease in mechanical properties, it shows STW-1 and STW-2 are not favourable in armchair and zigzag directions respectively. In addition, the effect of defects at different strain-rates and concentration on the fracture strength and failure morphology of graphene sheet has also been studied.