Biaxial and triaxial carbon fiber braids with off-axis braiding angles of 30°, 45°a nd 55°are characterized with respect to their fiber architecture. All braids are produced on a round mandrel with constant cross section. Detailed geometric information on the different braids, like roving dimensions, roving shapes and the degree of nesting is given. The findings from measurements in photomicrographs are used to construct meso-model yarn architectures at the unit cell level which are then analyzed with the WiseTex software (Lomov et al. Compos. Sci. Technol. 60:2083-2095, 2000. The results of the models' analysis with TexComp and comparison of mechanical properties with tests are consistent and essential for further steps in predictive modeling. Predictive modeling was also performed for biaxial braids based on the packing density in the material and parameters of the braiding process. The good conformance of the predictive models gives a validated starting point for development of braided structures concerning stiffness behavior. In addition, the information about the fiber architecture can be used for failure analysis on unit cell level.

Two-dimensional braiding of a generic preform has been undertaken using test, analytical and advanced explicit finite element simulation methods. The generic preform selected incorporates several important features including two cylindrical and one square section, a tapered cone and two dissimilar flanges. The analytical method has been shown to be computationally fast, but has limited accuracy and cannot directly predict braiding imperfections. Conversely, the explicit finite element method does require a complex model description, but has the capability to detect manufacturing imperfections and accurately predict yarn paths and yarn interactions. A detailed evaluation and comparison of the two methods is made against test results from the generic preform, which was deliberately manufactured to have both good and imperfect yarn architecture.

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