In crystalline materials, plasticity results from the motion of defects of the crystalline lattice, dislocations. The absence of structural order in glasses requires to look for alternative microscopic mechanisms for the plastic deformation. A common hypothesis consists in considering series of localized rearrangements of the amorphous structure : Shear Transformations. In this talk we review recent results obtained for the caracterization of such Shear Transformations at the atomic scale.

We first present a recent numerical method allowing to characterize local yield thresholds in model glasses prepared by molecular dynamics. We discuss their connection to the plastic activity observed upon shearing and their dependence on the protocol of preparation of the glass. We then present recent results obtained with lattice models of amorphous plasticity at a mesoscopic scale
and discuss first attempts of coarse-graining the plastic behavior of glasses from atomic scale to mesoscopic scale.

References:

S. Patinet et al. Connecting Local Yield Stresses with Plastic Activity in Amorphous Solids, Phys. Rev. Lett. 117, 045501 (2016)

B. Tyukodi et al. From depinning transition to plastic yielding of amorphous media: A soft-modes perspective, Phys Rev. E 93, 063005 (2016)