Local Mechanical Description of an Elastic Fold

TL;DR

This study combines experimental and elastic modeling approaches to characterize the local mechanical behavior of an annealed elastic fold in a polymer sheet, revealing differences under tension and compression.

Contribution

It introduces a continuous elastic model of a fold with a non-flat reference configuration, advancing understanding beyond simple hinge models.

Findings

Experimental measurements of fold shape and force response under various loads.

Elastic model accurately predicts local fold properties and explains tension-compression differences.

Asymptotic analysis identifies the origin of the fold's mechanical behavior.

Abstract

To go beyond the simple model for the fold as two flexible surfaces or faces linked by a crease that behaves as an elastic hinge, we carefully shape and anneal a crease within a polymer sheet and study its mechanical response. First, we carry out an experimental study that consists on recording both the shape of the fold in various loading configurations and the associated force needed to deform it. Then, an elastic model of the fold is built upon a continuous description of both the faces and the crease as a thin sheet with a non flat reference configuration. The comparison between the model and experiments yields the local fold properties and explains the significant differences we observe between tensile and compression regimes. Furthermore, an asymptotic study of the fold deformation enables us to determine the local shape of the crease and identify the origin of its mechanical behaviour.