Figure 2. Simulation of damage and failure during tensile loading of polycrystalline graphene.

(a) A schematic representation of the fracture simulation of a 2D periodic graphene nanoscale polycrystal. Each colour represents a grain within which the lattice orientation is fixed. The polycrystal is loaded at a constant strain rate. (b) Residual stress in a polycrystal; the principal stress is plotted in units of GPa. The interiors of the grains are stress free while there is significant residual stress at the GBs and TJs. The black arrow points to the large stress concentration at the tail of the pentagon–heptagon defect where fracture ultimately nucleates. The inset shows a zoom-in of the atomic configuration. (c) Principal stress just before global fracture. The crack nucleates at the GB defect and extends through the adjacent crystal. Notice that there are a few other incipient cracks that do not go unstable.