Figure 5.

Average fracture energy ($\mathcal{G}$) of crosswise incised films (μ=0.9 MPa) as a function of film thickness (h; circles). All of incisions were made to a maximum depth δ of ∼100 μm and spacing (s) of ∼250 μm. When h<100 μm (δ=h), the film has low fracture energy but the energy increases with the film thickness. When h>100 μm, $\mathcal{G}$ slowly reaches a plateau. This suggests that the fracture energy is strongly dependent on the incision depth. Error bars represent the standard deviation about the average fracture energy, which represents the magnitude of the stick–slip instability. The triangles represent the fracture energies of the smooth films that do not depend on h.