Three‐dimensional braided composites with auxetic behavior in the transverse plane and equal Poisson's ratios along principal directions

Abstract Analytical homogenization technique for obtaining elastic properties of three‐dimensional braided composites is presented. The effect of braiding angle on Poisson's ratios, configurations exhibiting equal Poisson's ratios along principal directions of braided composite representative unit cells (RUCs) and auxetic behavior in the transverse plane of RUCs are investigated. Two unique braided composite RUCs are presented. The exact jamming condition is utilized for obtaining braided composite configurations. The 4‐axes and 5‐axes arrangements are examined for each RUC. Obtained numerical results are compared with results reported in the literature. Equal Poisson's ratios along global orthonormal directions of both RUCs are achievable. Highlights Two RUCs for three‐dimensional braided composites have been identified. Composites with auxetic behavior are possible for a range of braiding angles. Composites with equal Poisson's ratios are possible for a few braiding angles.