Alberto Rosso - The fate of shear-oscillated amorphous solids

This talk was part of the Thematic Programme on "Non-equilibrium Processes in Physics and Biology" held at the ESI August 19 -- October 11, 2024.

In this talk, I will present a study that characterizes the behavior of shear-oscillated amorphous materials using a simplified, coarse-grained model. Through a series of oscillations, the material eventually reaches a steady state, which is determined by the initial preparation of the sample and the amplitude of the applied oscillations.

For materials that are poorly annealed, meaning they are less stable, small oscillations lead to further shear-annealing, making their structure more stable. On the other hand, ultra-stabilized materials, which are already highly stable, show minimal response to these small oscillations. However, when the oscillation amplitude exceeds a critical threshold, both types of materials experience a sudden, discontinuous transition. They shift into a mixed state where a fluid shear-band forms within a marginally stable solid matrix.

Additionally, the study establishes quantitative relationships between uniform shear and the steady state achieved under these conditions. The transient phase, which involves the development and movement of the shear band, is also explored to better understand the material's evolution toward this mixed state.