fig3

Figure 3. The measured fracture energy Γ as a function of incision diameter D. Ten sets of data are plotted as dots. The left three sets of data are fit to a horizontal line, Γ = Γ₀. The right seven sets of data are fit to an inclined line, Γ = k(D-D^*) + Γ₀. The two lines intersect at a critical length D^*. When D < D^*, Γ is independent of D; When D > D^*, Γ linearly increases with D.