Stress controlled rheology of dense suspensions using transient flows

TL;DR

This paper introduces a novel transient flow method to precisely control local stress in dense suspensions, enabling detailed study of shear jamming transitions that are difficult to probe with steady-state rheology.

Contribution

The authors develop and validate a technique using propagating shear fronts to control stress locally, allowing dynamic investigation of shear jamming in dense suspensions.

Findings

Successfully mapped the onset stress for shear jamming.

Demonstrated control of local stress conditions with transient flows.

Provided new insights into the dynamic approach to shear jamming.

Abstract

Dense suspensions of hard particles in a Newtonian liquid can be jammed by shear when the applied stress exceeds a certain threshold. However, this jamming transition from a fluid into a solidified state cannot be probed with conventional steady-state rheology because the stress distribution inside the material cannot be controlled with sufficient precision. Here we introduce and validate a method that overcomes this obstacle. Rapidly propagating shear fronts are generated and used to establish well-controlled local stress conditions that sweep across the material. Exploiting such transient flows, we are able to track how a dense suspension approaches its shear jammed state dynamically, and can quantitatively map out the onset stress for solidification in a state diagram.