Strain Localization Above the Yielding Point in Cyclically Deformed Glasses

We study the yielding behavior of a model glass under cyclic athermal quasistatic deformation and at finite rate and temperature, computationally, and show that yielding is characterized by the discontinuous appearance of shear bands, whose width is about ten particle diameters at their initiation, in which the strain gets localized. Strain localization is accompanied by a corresponding change in the energies and a decrease in the density in the shear band. We show that the glass remains well annealed outside the shear band, whereas the energies correspond to the highest possible energy minima at the given density within the shear band. Diffusive motion of particles characterizing the yielded state are confined to the shear bands, whose mean positions display movement over repeated cycles. Outside the shear band, particle motions are subdiffusive but remain finite. Despite the discontinuous nature of their appearance, shear bands are reversible in the sense that a reduction in the amplitude of cyclic deformation to values below yielding leads to the healing and disappearance of the shear bands.