# Shear-induced organization of forces in dense suspensions: signatures of discontinuous shear thickening

## TL;DR

This paper investigates the microscopic force network changes during discontinuous shear thickening in dense suspensions, revealing an order parameter that characterizes the transition from lubricated to frictional contacts.

## Contribution

It extends a formalism from dry granular materials to dense suspensions, providing a quantitative analysis of force network evolution during DST.

## Key findings

- Identification of microscopic force distribution changes
- Discovery of an order parameter for DST transition
- Linking microscopic interactions to macroscopic rheology

## Abstract

Dense suspensions can exhibit an abrupt change in their viscosity in response to increasing shear rate. The origin of this discontinuous shear thickening (DST) has been ascribed to the transformation of lubricated contacts to frictional, particle-on-particle contacts. Recent research on the flowing and jamming behavior of dense suspensions has explored the intersection of ideas from granular physics and Stokesian fluid dynamics to better understand this transition from lubricated to frictional rheology. DST is reminiscent of classical phase transitions, and a key question is how interactions between the microscopic constituents give rise to a macroscopic transition. In this paper, we extend a formalism that has proven to be successful in understanding shear jamming of dry grains to dense suspensions. Quantitative analysis of the collective evolution of the contact-force network accompanying the DST transition demonstrates clear changes in the distribution of microscopic variables, and leads to the identification of an "order parameter" characterizing DST.