VISCOELASTIC STUDIES OF TEXTILE FABRICS

Abstract

The flexible rigidities (EI) of the many kinds of fabrics (Table 1) are measured by heart loop method.(1) EI of fabric depends upon the bending mode of test piece. An EI of fabric having the long floats on its surface is smaller in face-to-face bending than back-to-back. (Fig. 1 & 2)(2) An EI of low freeness fabric is generally small, but there are many deviations from this tendency, e. g. in basket weaves.(3) An effect of crimp of component yarn of fabric to the EI of fabrics is generally small. When the crimp is of sine wave, apparent rigidity Da is: Where σ: a/b π, a: amplitude, b: the length of period. So, in the case of σ_??_1 a crimp efiect is very small and neglegible, ordinary fabrics are in this category.(4) The flexible rigidity of yarn calculated by means of dividing the fabric rigidity with yarn density EI (F) are generally larger than the true rigidity EI (T) of compornent yarn measured by the experiment.The rigidity factor S may can be descriced in general as;where l is true length contributing to yarn bending. In the ordinary fabrics, warp and weft yarns come in contract each other not at geometrical contact point but in contact length. So, true length l is shorter than in the case of ideal geometrical fabric model, i. e. l0=nl.i.e. S is proportional to n, n3 EI(T)=EI(F).In the ordinal clothing fabrics, n=1_??_1.16 (Table 3 & 4)We find that the bending mechanism of fabrics could be explained as the function of the rigidity of compornent yarn and fabric structure.