March 7, 2025
Keio University
Osaka University
A research group from Keio University and Osaka University has clarified the mechanism behind the natural curling phenomenon of knitted fabrics through a combination of experiments and simulations. The group includes Kotone Tajiri (a first-year master's student at the Graduate School of Science and Technology, Keio University), Tomohiko Sano (a full-time lecturer at the Department of Mechanical Engineering, Faculty of Science and Technology, Keio University), Ritsuki Murakami (a first-year master's student at the Graduate School of Engineering Science, Osaka University), Assistant Professor Shunsuke Kobayashi, and Professor Ryuichi Tarumi.
The stockinette stitch, one of the most basic knitting structures, consists of a periodic lattice of bent yarn, and a three-dimensional curled shape naturally occurs at the edges. Much of the research on the mechanical properties of knitted fabrics has been based on two-dimensional modeling, and the three-dimensional relationships have not been fully clarified. The curling behavior of knitted fabrics involves a complex interplay of forces and moments acting on the yarn, single-loop geometry, mechanical properties, and friction, thus requiring three-dimensional analysis. Therefore, in this study, the research group systematically created three-dimensional curled shapes that occur in rectangular stockinette structures using a knitting machine and demonstrated through experiments and simulations that the loop geometry and mechanical properties correlate with the curled shape. It was found that the curled shape changes according to the stitch count ratio and that the loop geometry affects the mechanical anisotropy of the knitted fabric. The results of this study suggest that changes in the single-loop geometry have the potential to control the overall three-dimensional natural shape of the knitted fabric. This is expected to contribute to the prediction of more complex three-dimensional shapes and the development of design and engineering techniques for industrial applications such as composite materials, wearable devices, and actuators using knitted fabrics.
The results of this research were published online in the British scientific journal "Extreme Mechanics Letters" on February 25, 2025.
Please see below for the full press release.