A trio of physicists from the University of Rennes, Aoyama Gakuin University, and the University of Lyon have discovered, through experimentation, that it is friction between fibers that allows knitted fabrics to take on a given form. Jérôme Crassous, Samuel Poincloux, and Audrey Steinberger have attempted to understand the underlying mechanics involved in the forms of knitted garments. Their paper is published in Physical Review Letters.
The research team noted that while many of the factors that are involved in intertwined fabrics have been studied to better understand their characteristics (such as why sweaters keep people warm despite the gaps between stitches), much less is known about the form garments made using such techniques can take.
To learn more, they conducted experiments using a nylon yarn and a well-known Jersey knit stitch called the stockinette—a technique that involves forming interlocked loops using knitting needles. They knitted a piece of fabric using 70×70 stitches and attached it to a biaxial tensile machine.
The team then used the tensile machine to stretch the piece of fabric in different ways, and then closely examined how it impacted the stitches. They found that the piece of garment did not have a unique shape. By stretching the fabric in different ways, they could cause it to come to rest in different forms, which they call metastable shapes.
They noted that the ratios of the length and width of such metastable shapes varied depending on how much twisting was applied, which suggested the fabric was capable of taking on many different metastable shapes.
The researchers then created simulations of the fiber to show what was happening as it was twisted and pulled on the tensile machine. The simulations showed the same results, but it allowed them to change one characteristic of the virtual fibers that could not be changed on the real fabric—the amount of friction between the strands.
They found that setting the friction to zero reduced the metastable shapes to just one. Thus, friction was found to be the driving force behind the forms that knitted fabrics can take.
More information:
Jérôme Crassous et al, Metastability of a Periodic Network of Threads: Shapes of a Knitted Fabric, Physical Review Letters (2024). DOI: 10.1103/PhysRevLett.133.248201. On arXiv: DOI: 10.48550/arxiv.2404.07811
© 2024 Science X Network
Citation:
The science behind your Christmas sweater: How friction shapes the form of knitted fabrics (2024, December 30)
retrieved 30 December 2024
from https://phys.org/news/2024-12-science-christmas-sweater-friction-fabrics.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
