ICAMS / Interdisciplinary Centre for Advanced Materials Simulation


Stress fluctuations, static yield stress and shear banding in a flowing Lennard-Jones glass

F. Varnik, L. Bocquet, L.-J. Barrat.

SPIE proceedings on Fluctuation and Noise in Materials, 5469, 209, (2004)

Using large scale molecular dynamics simulations, we study the non-linear rheology of a model glass (a 80:20 binary Lennard-Jones mixture). In a glassy state, this model exhibits shear banding at low imposed shear rates. This behavior seems to be closely related to the existence of a static yield stress, σy, and to the observation that, under imposed shear rate, σ(γ→0) < σy. We measure the static yield stress via simulations under imposed stress and investigate its dependence on temperature. For temperatures far below Tc (the mode coupling critical temperature of the model), σy hardly decreases upon heating whereas it changes much faster as Tc is approached. Furthermore, at extremely low shear rates, large stress fluctuations are observed which is reminiscent of the stick-slip motion observed in friction simulations. Our results, which open the possibility of exploring complex rheological behavior using simulations, are compared to recent experiments on various soft glasses.

DOI: 10.1117/12.547278
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