Fracture strength and fracture toughness of graphene: MD simulations

Abstract

An attempt is made here to address the fundamental issues on the validity of Griffith�s theory to estimate the fracture strength at nano-scales and valid a/W ratios to predict the fracture strength and fracture toughness of graphene, through molecular dynamics simulations. The influence of a/W ratio on the fracture toughness of graphene is systematically investigated through molecular dynamics simulations by adopting the hexagonal lattice structure of a mono-layer graphene sheet. Two different square domains with ten different lattice orientations and thirteen different initial crack lengths�are considered in�the analysis. Based on the results, the lower bound of the a/W ratio is defined as the�value beyond which Young�s Modulus starts to decrease with increase in a/W. On the other hand, fracture toughness is observed to increase with increase in a/W ratio until reaching the peak value, followed by a�decreasing trend with further increase in a/W ratios. Therefore, the upper bound of a/W ratio is recommended as the value beyond which fracture toughness starts to decrease. Accordingly, a range of 0.15<a/W<0.45 is recommended to predict the fracture toughness of graphene. � 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.