Circumferential buckling of a hydrogel tube emptying upon dehydration

TL;DR

This paper investigates the circumferential buckling of a hydrogel tube during dehydration, combining a nonlinear elastic model with Flory-Rehner theory to predict buckling thresholds and validate findings with finite element simulations.

Contribution

It introduces a combined chemo-mechanical model to predict buckling in dehydrating hydrogel tubes, accounting for large deformations and active behavior, with validation against simulations.

Findings

Buckling threshold depends on shell thickness, chemical potential, and material properties.

Model predictions align well with finite element simulation results.

Dehydration induces cavity depression leading to circumferential buckling.

Abstract

A cylindrical hydrogel tube, completely submerged in water, hydrates by swelling and filling its internal cavity. When it comes back into contact with air, it dehydrates: the tube thus expels the solvent through the walls, shrinking. This dehydration process causes a depression in the tube cavity, which can lead to circumferential buckling. Here we study the occurrence of such buckling using a continuous model that combines non-linear elasticity with Flory-Rehner theory, to take into account both the large deformations and the active behavior of the hydrogel. In quasi-static approximation, we use the incremental deformation formalism, extended to the chemo-mechanical equations, to determine the threshold value of the enclosed volume at which buckling is triggered. This critical value is found to depend on the shell thickness, chemical potential and constitutive features. The results obtained are in good agreement with the results of the finite element simulations of the complete dynamic problem.