Magnetic Resonance Imaging study of sheared granular matter

TL;DR

This study employs Magnetic Resonance Imaging to analyze shear zone geometries in granular materials, revealing significant differences based on material softness and fluid presence, advancing understanding of granular shear behavior.

Contribution

Introduces a novel MRI technique to visualize shear zones in granular matter, distinguishing effects of material softness and fluid embedding on shear zone geometry.

Findings

Shear zone geometry varies with material softness.

Fluid presence significantly alters shear zone structure.

MRI effectively visualizes internal shear profiles.

Abstract

We introduce a Magnetic Resonance Imaging technique to study the geometry of shear zones of soft, low-frictional and hard, frictional granular materials and their mixtures. Hydrogel spheres serve as the soft, low-frictional material component, while mustard seeds represent rigid, frictional grains. Some of the hydrogel spheres are doped with CuSO4 salt to serve as tracers. A split-bottom shear cell is sheared stepwise and the shear profiles are determined from the differences of tomograms after successive shear steps, using Particle Imaging Velocimetry.We find that the shear zone geometry differs considerably between soft grains submersed in water and the same material without the embedding fluid.