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arXiv · 1601.05671

Spatial repartition of local plastic processes in different creep regimes in a granular material

A Pons·T Darnige·Jérôme Crassous·E Clément·Axelle Amon
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Abstract

Granular packings under constant shear stress display below the Coulomb limit, a logarithmic creep dynamics. However the addition of small stress modulations induces a linear creep regime characterized by an effective viscous response. Using Diffusing Wave Spectroscopy, we investigate the relation between creep and local plastic events spatial distribution ("hot-spots") contributing to the plastic yield. The study is done in the two regimes, i.e. with and without mechanical activation. The hot-spot dynamics is related to the material effective fluidity. We show that far from the threshold, a local visco-elastic rheology coupled to an ageing of the fluidity parameter, is able to render the essential spatio-temporal features of the observed creep dynamics.

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A Pons, T Darnige, Jérôme Crassous, E Clément, Axelle Amon. 2016-01-21. Spatial repartition of local plastic processes in different creep regimes in a granular material. https://doi.org/10.1209/0295-5075/113/28001

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