FEM analysis of unit cell using single I-Fiber stitching process

The development and use of composite materials for several manufacturing industries require reliable adhesives and joints. However, the use of composite joints decreases the strength in the z-direction where composite laminates have lower strength. In this way, several methods have been proposed to reinforce CFRP laminates in the z-direction. Based on previous studies, a new technology in the through-thickness reinforcement for composite laminates called I-Fiber stitching process has been introduced, and the development continues under investigation. In the present research, the experimental results obtained from a unit-cell specimen under pull-out load with three different thicknesses and stitched with a single yarn using the I-Fiber stitching process were analyzed using the finite element method. Microscope image analysis was performed to obtain the best approach of the numerical model. Stress distribution of the I-Fiber and interface analysis using cohesive elements were achieved to understand the performance of the single stitch for each unit-cell case. Finally, a failure load comparison was performed between the experiments and the numerical analysis. The results showed the complexity of the I-Fiber shape under different laminate thicknesses and how the fiber volume of the reinforcement can vary along the thickness using the same stitching yarn for all cases.