Theoretical Modeling on the Deformation Behavior of Auxetic Tubular Braid Made from Modified Circular Braiding Technique

Herein, a theoretical analysis of auxetic tubular braid (ATB) formed with three types of component yarns having different diameter and modulus is presented. A simple theoretical model is developed for predicting the deformation behavior of this structure under uniaxial extension. With its accuracy first validated by the experimental data, the developed model is further corrected based on the real condition and thus becomes capable to characterize the auxetic behavior of the ATB. During the analysis, it is found that the stiff wrap yarn cannot be fully straightened in real condition and its helical angle decreasing rate is inconsistent during the stretching. Herein, an effective tool for understanding the deformation behavior is provided, which is meaningful for the braid's improved design and applications.