Local yield stress statistics in model amorphous solids

Armand Barbot (1, 2) , Matthias Lerbinger (3) , Anier Hernandez-Garcia , Reinaldo García-García (4) , Michael Falk (5, 6) , Damien Vandembroucq (3) , Sylvain Patinet (3)

1 ENS Paris Saclay - Ecole Normale Supérieure Paris-Saclay
2 Department of Physics [Kyoto]
3 PMMH - Physique et mécanique des milieux hétérogenes (UMR 7636)
4 LPCT - Laboratoire de Physico-Chimie Théorique
5 Department of Materials Science and Engineering [Baltimore]
6 Department of Physics and Astronomy [Baltimore]

We develop and extend a method presented in [S. Patinet, D. Vandembroucq, and M. L. Falk, Phys. Rev. Lett., 117, 045501 (2016)] to compute the local yield stresses at the atomic scale in model two-dimensional Lennard-Jones glasses produced via differing quench protocols. This technique allows us to sample the plastic rearrangements in a non-perturbative manner for different loading directions on a well-controlled length scale. Plastic activity upon shearing correlates strongly with the locations of low yield stresses in the quenched states. This correlation is higher in more structurally relaxed systems. The distribution of local yield stresses is also shown to strongly depend on the quench protocol: the more relaxed the glass, the higher the local plastic thresholds. Analysis of the magnitude of local plastic relaxations reveals that stress drops follow exponential distributions, justifying the hypothesis of an average characteristic amplitude often conjectured in mesoscopic or continuum models. The amplitude of the local plastic rearrangements increases on average with the yield stress, regardless of the system preparation. The local yield stress varies with the shear orientation tested and strongly correlates with the plastic rearrangement locations when the system is sheared correspondingly. It is thus argued that plastic rearrangements are the consequence of shear transformation zones encoded in the glass structure that possess weak slip planes along different orientations. Finally, we justify the length scale employed in this work and extract the yield threshold statistics as a function of the size of the probing zones. This method makes it possible to derive physically grounded models of plasticity for amorphous materials by directly revealing the relevant details of the shear transformation zones that mediate this process.

Domaines: Physique [physics]; Matière Condensée [cond-mat]; Mécanique [physics]; Mécanique des matériaux [physics.class-ph]; Mécanique des solides [physics.class-ph]; Physique [physics]

Armand Barbot, Matthias Lerbinger, Anier Hernandez-Garcia, Reinaldo García-García, Michael Falk, et al.. Local yield stress statistics in model amorphous solids. Physical Review E , 2018, 97 (3), pp.033001. ⟨10.1103/PhysRevE.97.033001⟩. ⟨hal-01710451⟩