Geometric Freedom in Bent Yarns and Fabrics

Abstract

The nature of the change in the geometrical restraints which occurs at the yarn crossover points during fabric bending is found from analysis of a simple waveform model of fabric crimp. This same model is also used to predict radial growth in bent, twisted multifilament yarns. The analysis shows that bending of idealized plain-woven fabrics will always result in increased amplitude of the fabric crimp and, for certain fabrics, a reduction in restraining forces on the crossing yarns. Similarly, bending of twisted multifilament yarns will always result in an increase in yarn diameter in the plane of bending and a decrease in the number of filament-to-filament contacts. Photographs of bent yarn and fabric structures illustrate these effects. The combined influence of both yarn radial growth and increased fabric free space on interyarn constraints is also discussed.