DEFORMATION OF THE YARN CROSS-SECTION IN THE FABRIC BY COMPRESSION

Abstract

Many theoretical studies about the fabric compressibility have been presented after F. T. Peirce (1947). There were, however, few reports which dealed with the behavior of the yarn in the fabric under compression. In this report, the deformation of the yarn in the fabric with compression, and the relation between the deformation and compressional properties of the fabric were clarified.
Microscopic pictures of the fabric cross-section were shown in Fig. 2. Deformations of the yarn cross-sectional shape were illustrated in Fig. 3. From the results, the yarn packing factor (1-ε) were calculated, and shown in Fig. 4. The pressure-thickness curves shown in Fig. 5 were represented as follow;
P=Be^{β(1-h/h_0.5)}
(P: pressure g/cm². B: constant 0.5g/cm². 1-h/h_0.5: stran, β: parameter)
The parameter β is a factor which represents the degree of the fabric compressibility. That is to say, the fabrics with low value of β are compressed easily. In both the twistless and twisted yarn fabrics, the strongest dependence was observed between the yarn packing factor (1-ε₀) and the parameter β as shown in Fig. 8. Here (1-ε₀) is the yarn packing factor in the fabric without compression. This means that the fabric compressibility depends on the yarn packing factor (1-ε₀). The relation between the changes of the yarn packing factor (1-ε) and compressional forces (_??_n P) were shown in Fig. 9. In twistless yarn fabrics with low fabric density, the yarn packing factor (1-ε) increased remarkably with compressional force in the region of 0_??_100g/cm² On the other hand, the yarn packing factor (1-ε) of the twisted yarn fabrics was hardly changed. These experimental results explain why the twistless yarn fabrics are felt more softly comparing with conventional twisted yarn fabrics.