Helix geometry model and mechanical property of 3D braided composites

On the basis of available studies, a helix geometry cell model of 3D braided composites is proposed. The yarns in the helix geometry model have been curved to avoid collision at the center of the unit cell and this coincides with the actual configuration of 3D braided composites. Based on the model, the stress field of the unit cell and the stress-strain curve is obtained. The mechanical properties, such as Young's modulus and Poisson's ratio, are calculated by a finite multiphase element method (FMEM). Compared with the experiment results, the study revealed that the helix geometry model prediction is more accurate than the conventional unit cell model.