▎ 摘　　要

For the first time, making use of scaled boundary finite element method (SBFM), critical intensity factors for the first, second and effective modes of angled cracks in a nano-graphene sheet were calculated. The results showed that by increasing the crack angle relative to the direction of the applied traction, the critical intensity factors decrease while increments in the crack length leave the factors almost unchanged. The simulation outcomes represented that the crack grows with respect to its initial orientation at multiple degrees of +/- 30 degrees. In contrast to what the Griffith criterion expects, the crack extension depends on the load direction and initial orientation. So, it can be deduced that Griffith criterion is not applicable for investigation of the crack growth in nano-graphene sheets.