The optimization of rotor spun yarn tensile model by changing-pitch system

This paper reports a refined model to predict the tensile behavior of rotor spun yarn from a knowledge of specimen specifications and yarn strain. Fundamental approaches used in yarn modeling include discrete-fiber-modeling principle, an energy method, and a “shortest-path” hypothesis. The study is carried out on the basic of a coaxial-helix structural model, taking account of non-uniform yarn packing density. Especially, changing-pitch system is first time introduced in yarn modeling. A pitch function has thus been determined by the aid of non-linear regression method and curve-fitting approach based on images obtained from tracer fiber technique.||Evaluation of the present model is also given against experimental data, together with a theoretical analysis of fiber strain distribution. It is confirmed that the present model is, due to the introduction of changing-pitch system, not only successful in explaining the experimental observations, but also believed in optimizing tensile drawing process.