Fig. 4.

Dynamic and static yield criteria. (A, Inset) Yield shear stress (${\tau }_{xz}^{yield}{d}^2/\left(mg\right)$) as a function of yield normal stress (${\sigma }_{zz}^{yield}{d}^2/\left(mg\right)$) for the dynamic yielding in different cases. The keys are the same as in Figs. 2 and 3. The lines are the fits of the Mohr–Coulomb failure equation. In the main plot, the variation of the dynamic macroscopic cohesive stress (${\tau }_c^{dyn}{d}^2/\left(mg\right)$) with the “effective” adhesive force $N_c^{eff}/mg$ for all of the cases. The straight line is the best fit to the data. (B, Inset) Yield shear stress (${\tau }_{xz}^{yield}{d}^2/\left(mg\right)$) as a function of yield normal stress (${\sigma }_{zz}^{yield}{d}^2/\left(mg\right)$) for the static yielding in different cases. The dotted lines are the guides to the eye, and the solid lines are the fits of the Mohr–Coulomb failure equation in the linear part of the data. The main plot shows variation of the static macroscopic cohesive stress (${\tau }_c^{stat}{d}^2/\left(mg\right)$) with the actual adhesive force $N_c/\left(mg\right)$. The dotted line is a guide to the eye, and the straight line is the best fit to the data.