Physics

Bundling architecture in elastic filaments with applied twist

Document Type

Article

Abstract

We investigate the formation of helical multifilament bundles and the torque required to achieve them as a function of applied twist. Hyperelastic filaments with circular cross sections are mounted parallel in a uniform circle onto end-clamps that can move along the twist axis depending on the applied axial load. With increasing twist, the filaments describe a hyperbolic hyperboloid surface before coming into contact in a circle and then packing in a tight helical bundle in the center with increasing twist. While the bundle appears ordered for sufficiently small number of filaments, they are disordered for large enough number of filaments and applied twist. We reveal with x-ray tomography that the packing of the filaments becomes disordered following a radial instability, which leads to a decrease in bundle radius and migration of filaments relative to each other in the bundle. Nonetheless, the helical angle of the filaments in the bundle are found to be essentially constant, resulting in inclination angles which increase with distance from axis of rotation. We develop energy minimization analysis to capture the observed variations in bundle length and torque as a function of number of filaments considering the neo-Hookean nature of the filaments. We show that the bundle geometry and the applied load can be used to describe the nonlinear torque profile measured as a function of twist angle.

Publication Title

Physical Review E

Publication Date

7-2025

Volume

112

Issue

1-2

ISSN

2470-0053

DOI

10.1103/d782-cbmc

Keywords

elastic deformation, tissue engineering, x-ray tomography

Cross Post Location

Student Publications

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