Study on the tensile behavior of helical auxetic yarns by modeling and mechanical analysis

Abstract

Two-component auxetic yarns with helical wrapping structure showed negative Poisson’s ratio under axial tension. It was the interaction force, especially the normal force, between the two filaments that led to the outer contour diameter of the complex yarn being expanded. Both the deformation behavior of structure and cross section presented greater effect on Poisson’s ratio and auxetic effect. However, the previous geometrical model that has been reported was without considering the interaction force between the two components. Mechanical model with axial tension and the normal force was carried out to theoretically calculate Poisson’s ratio of the complex yarn. The results showed that the cross section of the filament was from circular shape to elliptical shape under the normal force. Theoretical value from the mechanical model with considering the effect of normal force on the radial strain was in good accordance with the experimental results of Poisson’s ratio.