▎ 摘　　要

We use molecular dynamics simulations to study crack initiation and propagation in pre-cracked single layer arm chair graphene sheets deformed in simple tension by prescribing axial velocities to atoms at one edge and keeping atoms at the other edge fixed. It is found that the value of the J-integral depends upon the crack length, and for each initial crack length it increases with an increase in the crack length. Shorter initial cracks are found to propagate faster than longer initial cracks but shorter initial cracks begin propagating at higher values of the axial strain than longer initial cracks. Results computed for axial strain rates of 2.6 x 10(6), 2.6 x 10(7) and 2.6 x 10(8) s (1) reveal that values of the J-integral are essentially the same for the first two strain rates but different for the third strain rate even though the response of the pristine sheet is essentially the same for the three strain rates. (C) 2012 Elsevier B.V. All rights reserved.