Viscoelastic behavior of fibers during woven fabric bagging

The aim of this paper is to study the viscoelastic behavior of fibers durin g the woven fabric bagging process through a series of experiments and a ma thematical model to simulate bagging under the testing conditions. Through a large number of computational experiments, the elastic modulus E-1, visco elastic modulus E-2, fiber relaxation time tau and three weighting coeffici ents (k(3), k(4), k(5)) are determined for six woven fabrics made from diff erent fibers. A comparison of the experimental measurements with the predic ted bagging behavior of the fabrics reveals that the mathematical model is able to predict bagging behavior with reasonable accuracy. The results show that the viscoelastic behavior of fibers in the six fabrics is significant ly different during bagging. Nylon and polyester have a high elasticity rat io (E-1), a low viscoelasticity ratio (E-2), and a large relaxation time ta u. Silk, viscose, and cotton fibers have a low elasticity ratio (E-1), a hi gh viscoelasticity ratio (E-2), and a small relaxation time tau. For cotton and wool, with the same level of viscoelasticity (E-2), the stress relaxat ion process is determined by relaxation time tau. These results suggest tha t fiber viscoelastic behavior plays a key role in determining fabric rheolo gical behavior during bagging.