Deformation behaviors of auxetic warp knitted fabrics based on reentrant geometry

Abstract

A series of auxetic warp knitted fabrics based on reentrant geometry were developed in our previous study and their Poisson's ratio in the wale direction and course direction can be as low as −0.5 and −0.15, respectively. However, the quantitative relationships between structural parameters and auxetic effect, which can offer a guide to the design and manufacture process, are still unknown. Herein, the aim is to find such relationships. Based on the geometrical analysis, two semiempirical equations between Poisson's ratio and tensile strain are established when stretched in the wale direction and course direction, respectively. The study shows that the established semiempirical equations fit well with experimental results and can be used to predict auxetic effect of fabrics made with the same type of materials and similar structures. With the relationships proposed, warp knitted fabrics can be designed and manufactured directly without trials to obtain the desired auxetic effect, which can largely save the time and cost of production.