Capillary control of collapse in soft composite columns

TL;DR

This paper investigates how the spatial distribution of inclusions in soft composite columns influences Euler buckling, revealing methods to control buckling behavior through material inhomogeneity and elastocapillarity effects.

Contribution

It introduces a novel approach to manipulate buckling in soft composites by controlling inclusion distribution and size, extending classical buckling theory to inhomogeneous materials.

Findings

Inhomogeneous composites can be engineered to soften or stiffen under compression.

Gradient of inclusion volume fraction can control buckling modes.

Manipulation of elastocapillarity length affects buckling stability.

Abstract

Euler buckling is the elastic instability of a column subjected to longitudinal compression forces at its ends. The buckling instability occurs when the compressing load reaches a critical value and an infinitesimal fluctuation leads to a large amplitude deflection. Since Euler's original study, this process has been extensively studied in homogeneous, isotropic, linear-elastic solids. Here, we examine the nature of the buckling in inhomogeneous soft composite materials. In particular, we consider a soft host with liquid inclusions both large and small relative to the elastocapillarity length, which lead to softening and stiffening of a homogeneous composite respectively. However, by imposing a gradient of the inclusion volume fraction or by varying the inclusion size we can deliberately manipulate the spatial structure of the composite properties of a column and thereby control the nature of Euler buckling.