Cantilever Bending Behavior of Plain Weave Fabrics Constructed of Continuous Filament Cords

Abstract

Results are presented of a study of the cantilever bending behavior of plain weave fabrics constructed of continuous filament cords. Sample fabrics were produced from nylon tire yarn twisted into two-ply cords of the same construction used in an earlier cord , bending investigation. The number of picks and ends were varied in a predetermined fashion to provide tight, loose, and intermediate constructions. Cantilever bending tests carried out with selected samples of the fabrics indicated a bending behavior very similar to that observed in the cord bending study. That is, the end deflection 8 divided by the extended length l is proportional to the extended length cubed, once an initial threshold frictional constraint is overcome, providing the deflection ratio δ/ l does not exceed 0.50. Effective bending stiffness for the fabric samples was found to be much higher than that of the individual cords. This can be attributed to additional constraints introduced by the frictional forces at the cord crossover points. Based on experimental observation and other physical considerations, a mathematical model is proposed and presented for predicting the bending stiffness of the fabric samples as a function of the construction, the individual cord stiffness, and the frictional constraints expressed in terms of the initial extended length of sample l o required to overcome the initial threshold frictional state. Comparison of experimental and predicted values of lo indicate reasonable agree ment for the model when applied to the fabric samples possessing loose construction. For the tighter construction samples, the model predicts a higher value of lo / l than is measured. This, in turn, corresponds to a prediction of greater stiffness than is physically observed.