Figure 2. Failure measurements of the polycrystalline graphene in the presence of a hole.

(a) A hole exists right beneath the indenter tip (right panel) and at a GB junction (left panel) away from the indenter tip which is positioned on top of a grain center. The color indicates the von Mises stress. (b) The normal load vs. indentation depth curves. The dotted line represents the indentation result without a hole. It is seen that the relative position between the indenter tip and the hole gives rise to the large difference in failure load.