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Driven Glasses: from statistical physics to materials properties

Final Report Summary - GLASSDEF (Driven Glasses: from statistical physics to materials properties)

The glassdef project aimed at providing a physical description of the flow that can develop in soft amorphous solids such as pastes, dense emulsions, foams, under the application of external stresses. The project involves a multiscale approach in which a coarse grained description in terms of mesoscale elasto plastic models, motivated by detailed calculations at the atomic scale.
In the first part of the project the coarse grained description has been validated in comparison to experimental data and atomistic simulations. It was then used to tackle several outstanding problems in nonequilibrium statistical physics of driven materials:
- The peculiar structural relaxation induced by the elastic interaction between local plastic rearrangements.
- The characterization of the yield transition in terms of critical exponents and mean field analysis, highlighting the similarities and differences with the depinning transition.
- The mixed character of the yield transition and the mechanisms that can lead to coexistence between flowing and immobile regions.
Atomistic studies of driven materials was also extended to the study of more complex materials such as semi crystalline polymers or to simple models of living tissues, for which an analysis in terms of elastoplastic models is also underways. Fundamental questions concerning the applicability of quasi equilibrium concepts such as the Edwards measure theory to mechanically driven systems were also addressed for simple toy model systems, and could be extended to more realistic elastoplastic models in the future.