Kirsten Martens
140 Av. de la physique BP 87
F-38402 Saint Martin d'Hères
France
Phone: +33 4 76 51 47 41
Fax: +33 4 76 51 45 44
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Solid amorphous materials, under the application of sufficiently large
stresses, undergo plastic deformation and flow. Experimental results indicate
that the diffusion of tracer particles, e.g. in sheared foam systems and in
colloidal glasses, is shear rate dependent. Further observations concern the strong non-local effects in the mechanical response even
in quiescent regions far away from the flowing material, and the need for
a non local description to account for flow behavior in confined geometry.
At low strain rates the stress dynamics are governed by cooperative regions of
plastic events. We showed that there is a direct link between the self-diffusion
coefficient and the size of cooperative regions at low strain rates. Both
depend strongly on rate and on system size. A measure of the mean square
displacement of passive tracers in deformed amorphous media can thus give
information about microscopic rheology, such as the geometry of the cooperative
regions and their scaling with shear rate and system size.
Connecting diffusion and dynamical heterogeneities in actively deformed amorphous systems
Is there a connection between dynamical heterogeneities
and the self diffusion of tracer particles
in sheared amorphous media?
Typical accumulated activity of plastic events and typical non-affine displacement field both for small strain rates.
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