Macroscopic friction laws and shear yielding of glassy solids

Molecular simulations of yield in models of glassy polymers and amorphous metals are used to test classic yield criteria. Bulk systems follow the pressure-modified von Mises criterion, which is based on an isotropic, energy-driven model of yield. Thin films follow the Mohr-Coulomb criterion, which is based on an anisotropic friction model. The difference in behavior is correlated with a change in shear mechanism, and the connection between thin film results and macroscopic friction laws is discussed.