Bending rigidity of yarns using beam method on a two-support configuration

Abstract

This paper reports a simple, quick and reasonably accurate approach for measuring the bending rigidity of yarns. The beam method has been adapted and applied using a bending frame that has a fixed support and a simple support. The yarns are left to bend under the effect of their own weight. The accuracy and the precision of that bending frame are assessed over the time using an isotropic material and then compared against the ring-loop method and the KES-FB-2 pure bending tester. The findings show that the precision of this bending frame is acceptable. However, this bending frame gives at least 1.6 times greater values of bending rigidity than the KES-FB-2 pure bending tester, though the relationship between these two methods is linear and significant. Moreover, the spun yarns appear to have high levels of variability of the bending rigidity. This study is important as it overcomes the challenges faced while using other methods to measure the bending rigidity of yarn. It also provides a comprehensive account of the variation in this property. Further, it gives an indication of the highly non-uniform structure of spun yarns and the impact of yarn defects on the bending properties of yarns.