Surface Furrowing Instability in Everting Soft Solids

TL;DR

This paper investigates a novel surface buckling instability in soft elastic solids during extrusion, revealing how their unique rheology leads to furrow formation, with experimental and theoretical insights relevant to biomaterials.

Contribution

It introduces and characterizes a new surface instability in soft solids during extrusion, combining experimental observations with theoretical analysis.

Findings

Observed spontaneous buckling during extrusion of soft solids

Identified a furrow-like morphology deepening over time

Contrasted the instability with known elastic surface instabilities

Abstract

We report a surface instability observed during the extrusion of extremely soft elastic solids in confined geometries. Due to their unique rheological properties, these soft solids can migrate through narrow gaps by continuously everting the bulk material. The extrusion front spontaneously buckles in the direction transverse to the flow, resulting in a furrow-like morphology that deepens over time. We characterize the distinct features of this instability using experiments and theory and contrast the results with known elastic surface instabilities. Our study may provide insights into various processes involving the extrusion-like deformations of soft solids, including biomaterials.