Laboratoire Matière et Systèmes Complexes

Role of yield energy distributions in athermal amorphous materials under shear

Elisabeth Agoritsas, Eric Bertin, Kirsten Martens, and Jean-Louis Barrat (LIPhy, University Joseph-Fourier of Grenoble, France)

Abstract: Encompassing very dissimilar systems (such as foams, pastes, or metallic glasses), amorphous materials are composed of particles that can have very different shapes and sizes, such as grains of sand in a sandpile or bubbles in a soap foam. Lacking a crystalline structure, they exhibit a structural disorder that turns out to play a determinant role in their mechanical properties, while challenging their very description. Several elastoplastic models have been developed at the mesoscopic scale, in order to account for the plasticity in such amorphous systems, such as the Soft-Glassy-Rheology (SGR) model [1,2] and the Hébraud-Lequeux (HL) model [3]. These two mean-field models have proven to be rather successful in reproducing certain features observed in amorphous systems, but not all at once. Moreover, a consistent picture connecting these models is still missing. Here we discuss the physical ingredients that are put in those two mean-field models, distinguishing between thermal and mechanical noises in the mean-field dynamics of such amorphous materials. We focus in particular on the role of structural disorder, implemented by means of a distribution of energy barriers for the system to overcome when an external constant shear rate is applied to the material, and discuss specifically its implications for a generalization of the HL model.

[1] P. Sollich, F. Lequeux, P. Hébraud, & M. Cates, Phys. Rev. Lett. 78, 2020 (1997).

[2] P. Sollich, Phys. Rev. E, 58, 738 (1998).

[3] P. Hébraud & F. Lequeux, Phys. Rev. Lett. 81, 2934 (1998).

Vendredi 28 Novembre 2014 à 12h30 en salle 646A