Issue 38, 2017

Stress relaxation in viscous soft spheres


We report the results of molecular dynamics simulations of stress relaxation tests in athermal viscous soft sphere packings close to their unjamming transition. By systematically and simultaneously varying both the amplitude of the applied strain step and the pressure of the initial condition, we access both linear and nonlinear response regimes and control the distance to jamming. Stress relaxation in viscoelastic solids is characterized by a relaxation time τ* that separates short time scales, where viscous loss is substantial, from long time scales, where elastic storage dominates and the response is essentially quasistatic. We identify two distinct plateaus in the strain dependence of the relaxation time, one each in the linear and nonlinear regimes. The height of both plateaus scales as an inverse power law with the distance to jamming. By probing the time evolution of particle velocities during relaxation, we further identify a correlation between mechanical relaxation in the bulk and the degree of non-affinity in the particle velocities on the micro scale.

Graphical abstract: Stress relaxation in viscous soft spheres

Article information

Article type
23 Aug 2017
11 Sep 2017
First published
22 Sep 2017
This article is Open Access
Creative Commons BY license

Soft Matter, 2017,13, 6870-6876

Stress relaxation in viscous soft spheres

J. Boschan, S. A. Vasudevan, P. E. Boukany, E. Somfai and B. P. Tighe, Soft Matter, 2017, 13, 6870 DOI: 10.1039/C7SM01700F

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