The purpose of this paper is to mathematically model the structure of doubled fancy yarns made by combining together several threads.
It was assumed that such a structure may have two distinctive parts – sinusoidal and helical (i.e. sigmoidal). This model is based on calculating the length of the effect thread in relation to the core thread. The case of having several variants of such a structure was discussed to account for several types of doubled fancy yarns. The number of wraps of the binder, the overfed ratio, and heights of the fancy profiles in the different parts were the fundamental parameters of this model. The effects of changes in the number of wraps, the overfeed ratio or both simultaneously, on this model, were also considered. The shape factor of fancy yarn was also modelled depending on the basic model of the structure.
The model was tested and the correlation coefficient between the theoretical value and the real value of length of the effect thread was 0.90.
This model is useful for predicting the length of the effect component based on the type, dimension and number of the fancy profiles of doubled fancy yarn, and for understanding the changes of the multiple-thread structure of fancy yarn when the overfeed ratio and/or the number of wraps were to change.
