Modeling the tensile behavior of fiber bundles with irregular constituent fibers

In this paper, the effect of fiber dimensional irregularities on the tensile behavior of fiber bundles is modeled, using the finite element method (FEM). Fiber dimensional irregularities are simulated with sine waves of different magnitude. The specific stress-strain curves of fiber bundles and the constituent single fibers are obtained and compared. The results indicate that fiber diameter irregularity along fiber length has a significant effect on the tensile behavior of the fiber bundle. For a bundle of uniform fibers of different diameters, all constituent fibers will break simultaneously regardless of the fiber diameter. Similarly, if fibers within a bundle have the same pattern and level of diameter irregularity along fiber length, the fibers will break at the same time also regardless of the difference in average diameter of each fiber. In these cases, the specific stress and strain curve for the bundle overlaps with that of the constituent fibers. When the fiber bundle consists of single fibers with different levels of diameter irregularity, the specific stress-strain and load-elongation curves of the fiber bundle exhibit a stepped or &ldquo;ladder&rdquo; shape. The fiber with the highest irregularity breaks first, even when the thinnest section of the fiber is still coarser than the diameter of a very thin but uniform fiber in the bundle. This study suggests that fiber diameter irregularity along fiber length is a more important factor than the fiber diameter itself in determining the tensile behavior of a fiber bundle consisting of irregular fibers.<br /

Relation of Fiber and Fabric Properties in Durable-Press Cottons!

Abstract A cotton twill fabric was subjected to a durable-press treatment with dihydroxy dimethylol ethylene urea (Permafresh-183) of increasing severity. The mechanical properties of the fabrics and of single fibers withdrawn from the treated fabrics were evaluated and the relationships between fiber and fabric properties were analyzed. Statistically significant correlations between such important fabric properties as abrasion resistance. tear strength, tensile strength. and energy-absorbing capacity, on the one hand, and fiber mechanical properties, on the other, show conclusively that chemical treatments which alter fiber structure and properties are responsible for the modified fabric behavior. At the same time, the importance of fiber geometric arrangements in spun yarn and fabric structures. in terms of fabric properties, are pointed out. Thus, while this work has shown the functional relationships between fiber mechanical properties and fabric characteristics, careful attention must be given to fiber-fiber interactions. particularly in relation to chemical modification treatments