Torque Due to Applied Tension in Ring-spun Yarns

Abstract

A previous study showed that the torque in worsted wool yarns could be measured directly when the yarns were in the form of a hank under tension and that the torque could be split into two components, (a) the torque due to the applied tension and (b) the intrinsic torque at zero tension. This approach was applied to analyze the torque due to tension for a wide range of ring-spun worsted wool yarns of different structural parameters including yarn count, yarn twist and fiber diameter. The torque due to tension was measured on unsteamed and steamed yarns in dry and wet conditions and the data analyzed by applying mechanical models of yarn torque to estimate the yarn packing fraction. By using an effective linear density to evaluate the torque data, an estimate of the packing fraction of 0.63 allowed prediction of the torque in worsted wool yarns prepared from 18 to 24 micrometer diameter fibers across a wide range of yarn counts (16—80 tex) and wet and dry test conditions, and this approach was tested on some representative commercial wool worsted yarns. The effect of setting of worsted wool yarns on the torque due to applied load and the packing fraction was also identified and setting was shown to have little effect on the yarn torque due to tension.