A prediction method and its application for twist of slub yarn based on micro-element yarn

In the authors' previous work, slub yarn was simulated by randomly determining the fiber position with the Monte Carlo method according to the draft principle of ring-spun slub yarn. In this paper, the total torque of each micro-element yarn was calculated by considering the contribution of fiber bending, twisting and stretching to the torque of yarn body. The micro-element yarn is a regular ring-spun yarn. The twist of each micro-element yarn can be calculated according to the equal torque between micro-element yarns and the conservation law of twists. The twist curve along the yarn axis also can be obtained. The simulation values of the slub twist and base twist can be obtained by calculating the average twist of the slub apparent segment and that of the base apparent segment, respectively. The twist angle and diameters of the slub and base apparent segments of the spun slub yarn were measured using scanning electron microscopy images, enabling determination of the measured values for both slub twist and base twist. The average error rate of the simulated value compared with the measured value for slub twist was 7.654%, while for base twist, it was 7.745%. The relationships between slub length, base length, slub multiple, design twist, and both slub twist and base twist were investigated. The correlation coefficient (R) of the simulated and measured values was generally above 0.9, and the trend of the two was consistent. The work presented in this paper provides a basis for the development of virtual spinning technology.