Unravelling the Mechanics of Knitted Fabrics Through Hierarchical Geometric Representation

TL;DR

This paper develops a hierarchical, yarn-based dynamical model to understand and predict the nonlinear mechanical behavior and anisotropy of knitted fabrics, enabling design and engineering of functional textiles.

Contribution

It introduces a physically validated, hierarchical geometric model that captures fabric mechanics and anisotropy, advancing the understanding and design of knitted textiles.

Findings

Model accurately predicts fabric nonlinear response

Yarn rearrangements cause anisotropy

Design space for functional fabrics established

Abstract

Knitting interloops one-dimensional yarns into three-dimensional fabrics that exhibit behaviours beyond their constitutive materials. How extensibility and anisotropy emerge from the hierarchical organisation of yarns into knitted fabrics has long been unresolved. We sought to unravel the mechanical roles of tensile mechanics, assembly and dynamics arising from the yarn level on fabric nonlinearity by developing a yarn-based dynamical model. This physically validated model captures the fundamental mechanical response of knitted fabrics, analogous to flexible metamaterials and biological fiber networks due to geometric nonlinearity within such hierarchical systems. Fabric anisotropy originates from observed yarn-yarn rearrangements during alignment dynamics and is topology-dependent. This yarn-based model also provides a design space of knitted fabrics to embed functionalities by varying geometric configuration and material property in instructed procedures compatible to machine manufacturing. Our hierarchical approach to build up a knitted fabrics computationally modernizes an ancient craft and represents a first step towards mechanical programmability of knitted fabrics in wide engineering applications.