The application of fiber reinforced composites in multi material assemblies increases because of the potential to create products with low weight and high load capacity. The joining methods used in the industry, often require of drilling holes, which produce damage and weaken in the composite. This thesis is focused on describe a model to predict the orientation of the fibers in the union area, concretely when an embedded insert is located. This joining methodology allows the optimization of the fiber orientation, thus the fibers are relocated around the hole instead of cut them. The present work consists in different sequential stages. First, a study of the influencing factors might produce the curvilinear behavior is carried out. Then, using images from tested samples the real trajectories are described. And finally by statistical and geometrical analysis an analytical model to predict the orientation in the joining area is developed.