Torsional properties of staple fibre plied yarns
D.G. Phillips, C.-D. Tran, W.B. Fraser & G.H.M. van der Heijden
A mathematical analysis of the mechanical governing equations
applying to the torsional behaviour of multi-ply yarns under tension
has been carried out. This analysis clearly shows that there are two
components, a geometric component that determines the slope or
gradient of the torque due to tension and a component that
determines the yarn torque at zero applied tension (intrinsic
torque) that depends on the fibre number, fibre moduli and
diameter as well as the strand structural geometry. The effect of
the ratio of the ply twist to the spinning twist of the single
strands on the torque properties has been numerically analysed for
two, three and four-ply yarns prepared from single 31 tex yarns.
The model has been compared with experimental torque data for a
range of two-ply yarns plied at different percentages of the
singles spinning twist and also with different yarn histories and
test environments. The experimental data reflect the trends
identified by the model.
keywords: torque, tension, governing equations, torsion, bending, multi-ply
yarn, zero torque condition, fibre diameter, yarn count, yarn history,
experimental data, ply twist
The Journal of the Textile Institute 101, 595-612 (2010)