Numerical prediction for the elastic properties of three dimensional full five-directional braided composites

The three-dimensional full five-directional (3D full 5-directional) braided composite is a new kind of composite. It overcomes the following fatal shortcomings, which include the poor mechanical properties along the thickness direction, the low interlaminar shear strength and the inclined delamination of the traditional laminated composites. Its shock-damage-resistant performance, mechanical performance and fire-resistant performance are fairly good. In this paper, the finite element model is established by using the ANSYS software. The establishment is based on the micro-structure of 3D full 5-directional braided composites, the assumption of the braiding yarn with the hexagon section and the axial yarn with the square section, and the analysis of geometrical relationship of yarns in the space. The mechanical performance of this model is studied by the finite element method. The effective elastic constants are then obtained and compared with the corresponding results of 3D 5-directional braided composites. The influences of the braiding angle and fiber volume fraction on the properties of elasticity are also analyzed. The results show that 3D full 5-directional braided composite has good mechanical properties. Since the axial yarns are two times as much as that of 3D 5-directional braided composites, the axial mechanical performance has been further improved. In addition, when the braiding angle is relatively large, not only the merits of the 3D 5-directional braided composites can be maintained, the in-plane mechanical performances can also be enhanced on condition that the axial mechanical performance is not impaired.