Ordered buckling structures in a twisted crimped tube

TL;DR

This paper investigates how pre-creasing and boundary conditions influence the ordered buckling patterns in twisted tubes, revealing methods to control and design structured morphologies in soft materials.

Contribution

It demonstrates that pre-creasing and boundary conditions can induce ordered buckling structures in twisted tubes, expanding understanding of shell buckling control.

Findings

Pre-creasing leads to ordered triangular buckling patterns.

Ordered structures can form without pre-creasing in thicker sheets.

The torque response varies with boundary conditions and material thickness.

Abstract

When a ribbon or tube is twisted far enough it forms buckles and wrinkles. Its new geometry can be strikingly ordered, or hopelessly disordered. Here we study this process in a tube with hybrid boundary conditions: one end a cylinder, and the other end crimped flat like a ribbon, so that the sample resembles a toothpaste tube. The resulting irregular structures and mechanical responses can be dramatically different from those of a ribbon. However, when we form two creases in the tube prior to twisting, we obtain an ordered structure composed of repeating triangular facets oriented at varying angles, and a more elastic torque response, reminiscent of the creased helicoid structure of a twisted ribbon. We measure how the torque and structural evolution depend on parameters such as material thickness and the twist angle. When only part of the tube is pre-creased, the ordered structures are confined to this segment. Surprisingly, in some tubes made from thicker sheets, an ordered structure forms without pre-creasing. This study provides insights into controlling the buckling of thin shells, offering a potential pathway for designing ordered structures in soft materials.