A Methodology to Obtain the Accurate RVEs by a Multiscale Numerical Simulation of the 3D Braiding Process

To accurately evaluate the mechanical performance of three-dimensional (3D) braiding composites, it is essential to consider the braiding process and generate realistic representative volume element (RVE) structures. An efficient simulation methodology based on truss elements was used to simulate the 3D four-directional (3D4D) braiding process utilizing the finite element method (FEM) on the macroscale. The goal was to obtain the spatial trajectories of yarns and establish the relationship between the braiding parameters and the preform structure. Based on the initial yarn topology, the yarns were discretized as bundles of virtual sub-yarns. Then, a temperature drop simulation using hybrid elements was implemented to deform the yarn cross-section and obtain the interior, surface, and corner cells on the mesoscale. The simulation results show good agreement with the experiment. A parametric study was deployed to identify the effect of the model input parameters on the computation cost and accuracy. Furthermore, the approach applies to the other braiding processes, such as the cylindrical braiding composite.