Reversible and irreversible plastic events in a sheared amorphous solid - a mesoscopic approach

It was recently shown that the dynamics of a sheared amorphous solid under athermal and quasistatic shear (AQS) can be rigorously mapped into a state transition graph, where the vertices correspond to ensembles of microscopic particle configuration that remain mechanically stable over a range of strains [1,2]. We have called these ensembles mesostates, and the transitions between them constitute purely plastic events. This approach permits tracing out on a transition graph the AQS response under arbitrary shear protocols. The topology of the transition graph thus encodes the possible dynamics. Moreover, such transition graphs can be extracted from standard atomistic simulations of amorphous solids. At the same time, the transition graph topology provides a way of comparing the dynamics of different driven disordered systems. Here we show that graphs obtained from a mesoscopic model of a sheared amorphous solid faithfully reproduce key topological features of those extracted from atomistic simulations, providing a validation of our mesoscopic model [3,4]. We use the mesoscopic model to compare the topologies of transition graphs extracted from well- and poorly annealed amorphous solids.