Abstract: In this paper, a reasonable and effective mesoscopic geometrical model for 2×2 biaxial braided composite structure, and a calculation method for tensile modulus were eatablished. The geometrical model, which applys to single or multi-layer composites, was based on the practical factors such as cross-sectional performance, buckling of braided yarn bundle, actual weaving process and forming solidification. The calculation method of tensile modulus was also established, the simulation results are tend to be consistent with the actual numerical results, which proved the effectiveness of established model. The results show that the method is effective and feasible. The above results show that the meso-geometric model fit the structural characteristics of the monolayer and multi-layer 2×2 braided composites structure well. The equivalent mechanical model can reflect the tensile behavior of the composites and the tensile modulus can be accurately predicted.

Key words: 2D biaxial braiding, mesoscopic geometrical model, equivalent mechanical model, tensile modulus