Effects of structural parameters and performance on Poisson's ratio of auxetic yarn

Auxetic yarn is designed by ourselves by wrap-core structure, which has special physical properties and geometrical structure different from traditional yarn. The wrap-core auxetic yarn will expand transversely under tension. Therefore, the tensile tests were conducted to analyze effects of structural parameters and performance on lateral deformation of yarn. The experimental results show that yarn with negative Poisson's ratio as low as -4.31 is produced successfully. Moreover, effects of structure and performance, including the wrap angle, the diameter ratio, the tension modulus of the wrap yarn and the twist of the core yarn, on poisson's ratio of yarn are analyzed. It is found that the negative Poisson's ratio effect becomes more observable with the higher diameter ratio or lower wrap angle, and it becomes much more observable when the twist degree of the core yarn is higher or the wrap yarn's modulus is lower.