Abstract
This research comprises a theoretical investigation of the bundle twists created by the bundle thickness distribution while a bundle rotates by frictional force. The torque from the thickness differentials generates the twists of interest (i.e., the resulting rotation bundle differentials found in the friction area). Therefore, a theoretical model describing the dynamics of the twists per length was derived by applying continuous torque. The temporal bundle thickness is also considered. Using the model, the temporal profiles and spatial distributions of the torque twists are characterized. Under an arbitrarily chosen condition that allows simple interpretation of the torque twist characteristics, the governing equation system consisting of the model for the temporal distributions of the bundle radius on the friction drum surface and the model for the dynamic torque twists is solved, and the generation mechanisms of the torque twists are characterized. Results show that the torque twists propagate along the bundle axis in the form of a moving wave during the short time when the bundle first passes through the friction zone. After the bundle reaches a steady state, the torque twists increase very fast and then slow down as the bundle is moved by the take-up operation. Thus, the central area around the bundle axis becomes highly twisted by the superposition of the torque twists. This is because the input fleece fibers at the center accumulate for a longer distance than for the area near the bundle surface. However, at the exit of the friction area, the number of torque twists is almost zero because there is no accumulation distance for the torque twists to occur. This indicates that the torque twists are distributed with respect to the radial direction. This arc of torque-twist distribution can be described by a reciprocal relationship with respect to the radial position of the bundle cross-section.
