Effect Of Fiber Shape And Arrangement On Yarn Or Sliver Irregularity

Yarn or sliver irregularity is composed of the limit irregularity induced by fiber random arrangement in the yarn and additional irregularity caused by mechanical factors and spinning process. Generally, when irregularity theories are discussed, the former is given more consideration. Study of limit irregularity needs considering how fibers arrange in the sliver or yarn, which involves fiber geometrical properties and shapes in sliver or yarn.The first part introduced an experimental method to verify the assumption that left ends of fibers were uniformly distributed along the axis of yarn or sliver mentioned in the previous research about the structure. By counting the number of dyed tracer fibers contained in cotton sliver segment of given length, the verification was conducted using χ2 inspection method. Results show that the assumption is reasonable. The different length and fineness of cotton dyed tracer fibers were used in the experiment. The results showed that fiber length, fineness have no significant effects on the conclusion. In addition, viscose and acrylic dyed tracer fibers are selected in the experiment. It can be seen from the results that fiber length, fineness and type have no significant effects on the conclusion. By changing the length of sliver segment for further experiment, the results also have no significant effect on the assumption.The second part involved the measurement of cotton and ramie fiber straightness, hook types and their proportion as well as length and fineness are measured by tracer fibers. The effect of geometrical properties of cotton and ramie fibers on straightness is analyzed by correlation analysis and linear regression analysis. Results show that cotton fiber length and ramie fiber fineness have a significant influence on fiber straightness. The linear regression model between cotton fiber length and straightness is established.The third part further improved the method of simulation on fiber random arrangement in sliver or yarn, where fiber hook shape in sliver or yarn was considered and the assumption of fiber parallel and straight in sliver or yarn was weakened. The influence of hook shapes of cotton and ramie fibers on limit irregularity was analyzed by simulating fiber random arrangement in sliver or yarn. Results show that with the increase of average straightness, the limit irregularity declines. Limit irregularity in different hook types is tested with the Kruskal Wallis method. Results show that the fiber hook type has no significant influence on the limit irregularity. In addition, this chapter compared different situations of fiber length and fiber straightness. Limit irregularity in different situations was tested with Mann-Whitney U method. Results show that limit irregularity is relevant of fiber average length and average straightness, which will benefit for optimization of simulated process of predicting limit irregularity. Visual Basic is adopted to finish limit irregularity calculation application, the application can calculate limit irregularity by the input of the characteristic parameters of fiber and yarn.