Modelling the hysteretic wale-wise stretching behaviour of technical plain knits

This paper investigates the effect of friction on the stretching behaviour of plain-knits in the wale-wise direction. The capstan method was carried out to measure the yarn-to-yarn coefficient of kinetic friction between perpendicular yarns. The coefficient of kinetic friction between E-glass yarns and basalt yarns is similar and exhibits significant normal load sensitivity. However only E-glass yarns exhibit sensitivity to the sliding velocity. The yarn-to-yarn friction was then introduced in an existing semi-analytical model to simulate the wale-wise stretching of plain knits. This model was used to perform a sensitivity study, which has shown that friction significantly affects the knit behaviour both before and after jamming. The enhanced model proved to be able to properly describe the hysteretic behaviour of plain knits in the wale-wise direction. This allows concluding that friction at the loops crossing point is the main mechanism that controls the hysteretic behaviour of plain-knits, even if other mechanisms should be accounted for to perfectly describe the actual behaviour of the knit.