Estimating the deflection of weft yarn in plain woven fabric using yarn pull out test

Abstract

A simple and practical model has been proposed to calculate the deflection of weft in a plain woven fabric using yarn pull out test. In this modeling, the weft yarn is considered as an elastic beam, which is fixed supported at ends, and deflected at the middle by the normal load applied by the warp. The case of small deflection is adopted to calculate the maximum deflection of weft yarn and to study the shape and geometry of the bent weft. The normal load is estimated from pullout test. Bending rigidity of the weft yarn is calculated from the relation between the bending rigidities of fabric and thread. Five different weft densities have been studied. The shape of actual weft has been studied by microscopic photography from the lateral section of the fabric, and compared to the theoretical deflection curve of weft based on small deflection modeling. The results show that the actual and theoretical curves are reasonably close to each other. The maximum deflection of the weft yarn increases as the weft density (picks/cm) increases. This may be due to the increase in normal load in higher densities of the weft yarns. The results also show that the deviation of theoretical curve from the actual curve increases with the decrease in weft density.