Finding bridges in packings of colloidal spheres

TL;DR

This paper identifies and analyzes load-bearing structures called bridges in experimental colloidal sphere packings, demonstrating their similarity to those in granular simulations and proposing a new method for their detection.

Contribution

It introduces a novel bridge-finding procedure and a new criterion (LSQS) for analyzing load-bearing structures in real colloidal systems, bridging the gap between simulations and experiments.

Findings

Bridges similar to those in granular simulations are present in experimental colloidal packings.

The proposed LSQS criterion improves the identification of stable structures.

Experimental data confirms the role of bridges in force transmission.

Abstract

We identify putative load-bearing structures (bridges) in experimental colloidal systems studied by confocal microscopy. Bridges are co-operative structures that have been used to explain stability and inhomogeneous force transmission in simulated granular packings with a range of densities. We show that bridges similar to those found in granular simulations are present in real experimental colloidal packings. We describe critically the bridge-finding procedure for real experimental data and propose a new criterion-Lowest Mean Squared Separation (LSQS)-for selecting optimum stabilisations.