Mapping forces in 3D elastic assembly of grains

TL;DR

This paper demonstrates how X-ray microtomography combined with image analysis can effectively characterize the internal structure, contact forces, and stress distribution in 3D granular materials, advancing experimental capabilities.

Contribution

It introduces a novel method to measure contact forces and internal stress tensors in 3D granular systems using X-ray microtomography and image analysis.

Findings

Successful 3D microstructure characterization of granular packings

Quantification of contact forces and internal stress tensors

Potential for advanced static and dynamic measurements in 3D systems

Abstract

Our understanding of the elasticity and rheology of disordered materials, such as granular piles, foams, emulsions or dense suspensions relies on improving experimental tools to characterize their behaviour at the particle scale. While 2D observations are now routinely carried out in laboratories, 3D measurements remain a challenge. In this paper, we use a simple model system, a packing of soft elastic spheres, to illustrate the capability of X-ray microtomography to characterise the internal structure and local behaviour of granular systems. Image analysis techniques can resolve grain positions, shapes and contact areas; this is used to investigate the material's microstructure and its evolution upon strain. In addition to morphological measurements, we develop a technique to quantify contact forces and estimate the internal stress tensor. As will be illustrated in this paper, this opens the door to a broad array of static and dynamical measurements in 3D disordered systems