Understanding the dynamics of sheared amorphous solids in terms of plastic transition graphs and their topologies

by Prof. Ido Regev

at Condensed Matter Seminar

Mon, 03 Jan 2022, 11:30
Sacta-Rashi Building for Physics (54), room 207


Recent experiments and simulations of amorphous solids plastically deformed by an oscillatory drive have found a surprising behavior - for small strain amplitudes, the dynamics can be reversible, which is contrary to the usual notion of plasticity as an irreversible form of deformation. This reversibility allows the system to reach limit-cycles in which plastic events repeat indefinitely under the oscillatory drive. It was also found that reaching reversible limit-cycles can take a large number of driving cycles, and it was surmised that the plastic events encountered during the transient period are not encountered again and are thus irreversible.
We use a graph representation of the stable configurations of the system and the plastic events connecting them to map portions of the energy landscape.
Using the graph representation, we show that the notion of reversibility in these systems is more subtle. We find that reversible plastic events are abundant and that a large portion of the plastic events encountered during the transient period are actually reversible, in the sense that they can be part of a reversible deformation path. More specifically, we observe that the transition graph can be decomposed into clusters of configurations that are connected by reversible transitions. These clusters are the strongly connected components of the transition graph, and their sizes turn out to be power-law distributed.
We use the same graph representation to study the irreversibility transition - the divergence of the transient period at a critical forcing amplitude. We show that the dynamics can be thought of as transitions between clusters of reversibility in a search for a cluster large enough to contain a limit-cycle of a specific amplitude. For amplitudes close to the irreversibility transition, the search time becomes very large due to changes in the size and topology of the graph.

Relevant publications:

Mungan, Muhittin, Srikanth Sastry, Karin Dahmen, and Ido Regev. "Networks and hierarchies: How amorphous materials learn to remember." Physical review letters 123, no. 17 (2019): 178002.

Ido Regev, Ido Attia, Karin Dahmen, Srikanth Sastry and Muhittin Mungan, "Topology of the energy landscape of sheared amorphous solids and the irreversibility transition"
Physical Review E, no. 103 (2021): 062614

Created on 23-12-2021 by Meidan, Dganit (dganit)
Updaded on 28-12-2021 by Meidan, Dganit (dganit)