Period fissioning and other instabilities of stressed elastic membranes

TL;DR

This paper investigates the complex shapes and instabilities of elastic membranes under combined tension and compression, predicting new morphological phases and explaining recent experimental observations of pattern periodicity.

Contribution

It introduces a theoretical framework for understanding membrane instabilities and predicts novel morphological phases in a specific parameter regime.

Findings

Prediction of multiple new membrane morphologies

Explanation of pattern periodicity increase in wrinkled membranes

Identification of regimes with dominant tension and large wavelength contrast

Abstract

We study the shapes of elastic membranes under the simultaneous exertion of tensile and compressive forces when the translational symmetry along the tension direction is broken. We predict a multitude of novel morphological phases in various regimes of a 2-dimensional parameter space $(\epsilon,\nu)$ that defines the relevant mechanical and geometrical conditions. Theses parameters are, respectively, the ratio between compression and tension, and the wavelength contrast along the tension direction. In particular, our theory associates the repetitive increase of pattern periodicity, recently observed on wrinkled membranes floating on liquid and subject to capillary forces, to the morphology in the regime ($\epsilon \ll 1,\nu \gg 1$) where tension is dominant and the wavelength contrast is large.