Yarn Performance During Weaving

In the traditional approaches to the problem of assessing warp yarn performance on the loom, researchers have investigated tensile strength of sized yarn and attempted to correlate it with weavability [18,19]. However, the use of such tensile strength approach has not shown consistent correlations to weavability because the process of weaving is far more complex and several authors have raised doubts as to this approach [20,21]. The failure of sized yarns on a loom is attributed to the cumulative damage caused by cyclic fatigue of relatively small forces combined with abrasion [22]. The failure of warp yarns on a loom is caused by repeated cyclic elongation at small stresses well below the breaking point applied under static load [23,24]. The phenomenon commonly known as fatigue [25],is caused by the gradually diminishing resistance of the material, attributable to cumulative damage. Earlier attempts to characterize the fatigue performance of various materials, including textiles, were made in terms of average, median, or logarithmic lifetimes [26-281. Fatigue behavior of sized staple yam under cyclic loading follows three parameter Weibull distribution [23,26-281. However, some studies have reported unimodal [29] distribution whereas other studies have shown bimodal distribution 1301. This poses a formidable problem in understanding the mechanism of yam failure under tensile loading, since the mechanism involved in bimodal behavior is inherently different from that in unimodal Weibull distribution [23].