A novel geometric model of four-directional 3D braided preforms

The present research reports the geometric model of four-directional 3D (4D3D) braided preform developed on four-step 3D braiding machine which consists of even and an equal number of yarn carriers in the rows and columns, respectively, on machine bed. The yarn path within the unit cell of the preform was analyzed to establish the correlation between surface braiding angle and interior braiding angle. A single unit cell model approach was used to predict the fibre volume fraction of the preform. It has been observed that the number of yarn carriers in the rows and columns is a critical parameter to decide the geometry of 4D3D braided preform. The fibre volume fraction predicted by the present model was compared with the three-unit cell model, multi-unit cell model and experimental results. A good agreement was observed between model computed results and experimental results.