Séminaires CINaM

jeudi 12 septembre 2019 à 14H00

CINaM - Salle Raymond Kern

Sylvain Patinet

PMMH, ESPCI Paris/CNRS-UMR 7636/Univ. Paris 6 UPMC/Univ. Paris 7 Diderot, PSL Research Univ., 10 rue Vauquelin, 75231 Paris cedex 05, France

Local yield stress statistics in model amorphous solids

We develop and extend a method to compute the local yield stresses at the atomic scale in model two-dimensional Lennard-Jones glasses produced via differing quench protocols [1-2]. 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. 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. The local yield stress varies with the shear orientation tested and strongly correlates with the plastic rearrangement locations when the system is sheared correspondingly. Plastic rearrangements appear therefore as the consequence of shear transformation zones encoded in the glass structure that possess weak slip planes along different orientations. We then justify the length scale employed in this work and extract the yield threshold statistics as a function of the size of the probing zones.

Finally, the evolution of local yield stress distributions upon shear deformation is studied [3]. We show how the plasticity-induced anisotropy in amorphous solids can be explained by the depletion of the soft zones in the direction of deformation with respect to the reverse direction. In the most relaxed system, systematically presenting a localization of the plastic deformation through the formation of a shear band, the persistence of plastic activity is explained by local softening.

It is thus argued that 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.

References

[1] S. Patinet, D. Vandembroucq, and M. L. Falk, Connecting Local Yield Stresses with Plastic Activity in Amorphous Solids. Phys. Rev. Lett., 117, 045501, (2016).

[2] A. Barbot, M. Lerbinger, A. Hernandez-Garcia, R. Garcı́a-Garcı́a, M. L. Falk, D. Vandembroucq, and S. Patinet. Local yield stress statistics in model amorphous solids. Phys. Rev. E, 97, 033001 (2018).

[3] A. Barbot, M. Lerbinger, A. Lemaı̂tre, D. Vandembroucq and S. Patinet, Rejuvenation and Shear-Banding in model amorphous solids, submitted (2019).

 

Invitation : Céline Varvenne - Entrée libre