Shear-jamming in two-dimensional granular materials with power-law grain-size distribution

A. Herman, Entropy, 15, 4802-4821 (2013).

Although substantial progress has been made in recent years in research on sheared granular matter, relatively few studies concentrate on the behavior of materials with very strong polydispersity. In this paper, shear deformation of a two-dimensional granular material composed of frictional disk-shaped grains with power-law size distribution is analyzed numerically with a finite-difference model. The analysis of the results concentrates on those aspects of the behavior of the modeled system that are related to its polydispersity. It is demonstrated that many important global material properties are dependent on the behavior of the largest grains from the tail of the size distribution. In particular, they are responsible for global correlation of velocity anomalies emerging at the jamming transition. They also build a skeleton of the global contact and force networks in shear-jammed systems, leading to the very open, “sparse” structure of those networks, consisting of only 35% of all grains. The details of the model are formulated so that it represents fragmented sea ice moving on a two-dimensional sea surface; however, the results are relevant for other types of strongly polydisperse granular materials, as well.

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