Random packings of granular chains are presented as a model polymer system to investigate the contribution of entanglements to strain-stiffening in the absence of Brownian motion. The chain packings are sheared in triaxial compression experiments. For short chain lengths, these packings yield when the shear stress exceeds a the scale of the confining pressure, similar to packings of spherical particles. In contrast, packings of chains which are long enough to form loops exhibit strain-stiffening, in which the effective stiffness of the material increases with strain, similar to many polymer materials. The latter packings can sustain stresses orders-of-magnitude greater than the confining pressure, and do not yield until the chain links break. X-ray tomography measurements reveal that the strain-stiffening packings contain system-spanning clusters of entangled chains.
@article{arxiv.1108.3315,
title = {Strain-stiffening in random packings of entangled granular chains},
author = {Eric Brown and Alice Nasto and Athanasios G. Athanassiadis and Heinrich M. Jaeger},
journal= {arXiv preprint arXiv:1108.3315},
year = {2015}
}
Comments
4 pages, 4 figures. submitted to Physical Review Letters