Shear Jamming in Granular Experiments without Basal Friction

TL;DR

This study investigates how basal friction influences shear jamming in granular materials, demonstrating that while basal friction shifts the jamming point, it does not alter the fundamental shear jamming phenomenon.

Contribution

It provides experimental evidence on the role of basal friction in shear jamming, clarifying its effect on the jamming transition in granular systems.

Findings

Basal friction shifts the shear jamming point.

Shear jamming occurs regardless of basal friction presence.

Removing basal friction does not eliminate shear jamming.

Abstract

Jammed states of frictional granular systems can be induced by shear strain at densities below the isostatic jamming density ($\phi_c$). It remains unclear, however, how much friction affects this so-called shear-jamming. Friction appears in two ways in this type of experiment: friction between particles, and friction between particles and the base on which they rest. Here, we study how particle-bottom friction, or basal friction, affects shear jamming in quasi-two dimensional experiments. In order to study this issue experimentally, we apply simple shear to a disordered packing of photoelastic disks. We can tune the basal friction of the particles by immersing the particles in a density matched liquid, thus removing the normal force, hence the friction, between the particles and base. We record the overall shear stress, and particle motion, and the photoelastic response of the particles. We compare the shear response of dry and immersed samples, which enables us to determine how basal friction affects shear jamming. Our findings indicate that changing the basal friction shifts the point of shear jamming, but it does not change the basic phenomenon of shear jamming.