Centre de Physique Théorique


Jeudi 27 février 2020

11h00 – 12h00, Amphi 5 du CPT

Brittle yielding of amorphous solids at finite shear rates

Murari Singh (L2C, Montpellier)

Amorphous solids display a ductile to brittle transition as the kinetic stability of the quiescent glass is increased, which leads to a material failure controlled by the sudden emergence of a macroscopic shear band in quasi-static protocols. We numerically study how finite deformation rates influence ductile and brittle yielding behaviors using model glasses in two and three spatial dimensions. We find that a finite shear rate systematically enhances the stress overshoot of poorly-annealed systems, without necessarily producing shear bands. For well-annealed systems, the non-equilibrium discontinuous yielding transition is smeared out by finite shear rates and is accompanied by the emergence of multiple shear bands, as reported in metallic glass experiments. We show that the typical size of the bands and the distance between them increases algebraically with the inverse shear rate. We provide a dynamic scaling argument for the corresponding length- scale, based on the competition between the deformation rate and the propagation time of the shear bands.