Automatically generated geometric description of 3D braided rectangle preform

Based on the study of moving regulation of yarns in the carbon fiber preform, the yarn unit model with elliptical cross section was presented. This model involved the cross-section deformation and the space orientation of yarn through which the braided structure and the braiding parameters were connected. A software was developed by employing the model on which the integral geometric descriptions of 3D braided preform with different parameters were automatically generated. As a result, the pore’s shape and distribution among the yarns in the preform were expressed clearly. The effect rule of the braiding parameters on the shape and volume of the pores in the preform was that the pores became smaller and more separated with the increasing of the fiber volume fraction when the other parameters were invariant. The geometric descriptions are helpful for the calculation of whole permeability values for braided preform and the investigation of yarn stress distributions in 3D braided preform.