Multi-scale modeling and elastic properties prediction of 3D four-directional tubular braided composites

In recent years, with the widespread uses of three-dimensional four-directional (3D4D) tubular braided composites in daily life, accurate prediction of their elastic properties has become more and more important. This work presents a detailed parametric model of 3D4D tubular braided composites considering the mathematical relations between structural parameters of braided composites. The corresponding multi-scale finite element method and analytical method are proposed to predict the elastic properties of tubular braided composites and yarns, and the accuracy of the modeling method is verified by experiments. Also, the effects of braiding angle and fiber volume content on the elastic properties of 3D4D tubular braided composite are discussed. Furthermore, a homogeneous full-scale model is established to evaluate the macroscopic properties of 3D4D tubular braided composites. The results show that no matter how the geometric parameters change, the prediction of the elastic properties of the analytical model is consistent with that of FEM. It is also proved that the elastic properties of 3D4D tubular braided composites are affected by the braiding angle and the fiber volume content. The results of the homogenization model are in good agreement with those of the corresponding full-size model, which verifies the validity of the homogenization method.