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

Abstract

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.