The load-extension properties of continuous filament model yarns

A theoretical and experimental study has been made of the load-extension properties of simple models of yarn structure in which the filaments (nylon or Terylene) are arranged in a regular pattern. The theoretical treatment, which relies on a knowledge of the load-extension behaviour of the constituent filaments, is concerned with two stress systems. In one the stresses along the filament axes only are considered; in the other the lateral stresses between the filaments are taken into account. It is shown that the load-extension behaviour of medium-tenacity yarns is satisfactorily predicted, but for high-tenacity yarns at high twists there is a large discrepancy between theory and experiment, the cause of which has not been firmly established.