Determining Mechanical Properties of Yarns and Two-Ply Cords from Single-Filament Data

The objective of this research is to construct a computer model that can predict the properties of flat yams, twisted yams, and twisted cords from single-filament data. In this model, a modulus versus strain curve is obtained by taking the derivative of the average stress-strain curve from single-filament tensile tests. The distribution of elongation to break is then fit to a Gaussian curve and a relationship is derived between filament elongation and bundle elongation in a twisted structure. Using the principle of conserva tion of energy, the forces from the surviving filaments at a specific strain are summed to yield the resulting force on a ply, which is then used to calculate the tensile force on the cord. The model also predicts elongation to break, tenacity at break, and initial modulus of yams and cords.