The Torque Generated in Single and Multi-Ply Yarns as a Function of Changes in Yarn Tension

Abstract

This paper presents a theoretical and experimental investigation of the torque generated in a yarn as a result of a change in applied tensile stress. Single and plied yarn structures are analyzed, and it is shown that for small elastic extensions of a yarn, the change in yarn torque is linearly related to the applied tensile force P and also to the yarn twist. For plied yarns, a ratio of ply twist to single-yarn twist exists, for which the structure is torsionally insensitive to changes in applied tension. An expression is derived, relating this twist ratio to the yarn geometry, and values of 0.33, 0.20, and 0.11 are experimentally verified for 2-, 4-, and 7-ply yarns, respectively.