Theoretical prediction of the elastic properties of three dimensional and four-directional braided composites

On the basis of structural analysis for the three-dimensional four-step (1×1) braided composites, further improvement was made on the three-cell model which includes interior, surface and corner cells. The modified model realizes the geometric continuity of the fibers in the space, and also really simulates the moving orientation of fibers in the braided preforms. Based on this model, it is predicted that the elastic properties of three-dimensional and four-directional braided composites with the method of stiffness averaging. Comparison of the calculating results with the available experimental data shows the applicability of the present model.