Fiber-level bi-axial braid simulation for braid-trusion

Braid-trusion is a manufacturing process using a braided textile preform that is pulled into a pultrusion die. This process produces constant cross-section beams having reinforcement fibers oriented along the braid angle. The bi-axial braids are made from commingled yarns mixing carbon fibers and thermoplastic filaments. The bi-axial braid architecture is locked by the contacts between the bulky carbon/thermoplastic yarns. During pultrusion, the thermoplastic filaments melt. At this moment, the processing tensile loads adjust the braid architecture. The braid angle and the braid diameter reduces by reaching another locked state. This second locked state is driven by contacts between carbon yarns. The aim of this research is to model the braid deformation at the fiber scale using a non-linear finite element method. The model geometry is set up by the helix sinusoidal relations of the yarns path along a braid pitch. The braid large deformation is precisely modeled via a bundle of three-dimensional beam elements. The intertwined fibers contacts are modeled within a dynamic explicit solution. The model is validated with CT Scans of carbon fiber braids. This work will help the design of braid architecture for braid-trusion manufacturing.