11—A STUDY OF YARN TORQUE AND ITS DEPENDENCE ON THE DISTRIBUTION OF FIBRE TENSILE STRESS IN THE YARN PART I: THEORETICAL ANALYSIS

Abstract

Abstract The torque generated during yarn-twisting is considered to have three components, due, respectively, to fibre torsion, fibre-bending, and the internal fibre tensile and compressive stresses within the yarn. An analysis of the yarn torque generated by fibre torsion will be given in a later paper, and the component due to fibre-bending has been evaluated by other authors. It is proposed that the nature of the fibre tensile-stress distribution within a yarn is likely to be the most influential factor governing the magnitude of yarn torque. The distribution of stress, as a function of the fibre position in the yarn, depends largely on the facility with which fibres can migrate throughout the yarn cross-section. In this paper, two limiting forms of fibre geometry are considered: no migration, and complete fibre equivalence as a direct consequence of migration. For each case, the fibre-stress distribution is analysed, and the component of yarn torque due to these stresses is derived.