Nonlinear Elasticity of Flow-Stabilized Solids

TL;DR

This study investigates the nonlinear elastic behavior of flow-stabilized microsphere heaps, revealing tunable mechanical properties and universal stress-strain responses influenced by many-body interactions and a thermal van der Waals model.

Contribution

It introduces a novel experimental setup to measure the nonlinear elasticity of flow-stabilized solids and demonstrates the applicability of a thermal van der Waals equation to predict their stress-strain behavior.

Findings

Elastic modulus and interparticle separation are tunable via confining stress.

Stress-strain curves exhibit a universal nonlinear shape.

Many-body interactions significantly contribute to the stress support.

Abstract

Thermal fluctuations, geometric exclusion, and external driving all govern the mechanical response of dense particulate suspensions. Here, we measure the stress-strain response of quasi-two-dimensional flow-stabilized microsphere heaps in a regime in which all three effects are present using a microfluidic device. We observe that the elastic modulus and the mean interparticle separation of the heaps are tunable via the confining stress provided by the fluid flow. Furthermore, the measured stress-strain curves exhibit a universal nonlinear shape which can be predicted from a thermal van der Waals equation of state with excluded volume. This analysis indicates that many-body interactions contribute a significant fraction of the stress supported by the heap.