Abstract
An extended theory of the large deformation mechanics of twisted filament yarns is presented by taking account of the possible change in fiber orientation in the process of elongation. The theory makes it possible to predict the stress-strain relations of twisted yarns based on the orientation distributions of fibers in the unstressed states and on the elongation property of the constituent fiber, without using particular models of the yarn structure such as multi-helix models.
It was found that, in the whole range of yarn strain, theoretical predictions obtained on a few assumptions for the simplicity are in good agreement with the experimental results in the cases of moderately twisted yarns.
