Theoretical modeling for the exit-delamination morphology of the unidirectional CFRPs

Accurate exit-delamination morphology (i.e., shape and size) is of great significance both to evaluate and to control for the delamination during the drilling of carbon fiber-reinforced plastics. However, the morphology of the exit delamination in different fiber orientations is still difficult to precisely predict. In this paper, a theoretical model is established based on the classical bending theory of beam and the linear elastic fracture mechanics for determining the exit-delamination morphology. Based on this theoretical model, the accurate exit-delamination morphology can be precisely predicted. The results show that the exit-delamination zone is near to the elliptical shape, and its size decreases with the increasing of the cutting speed but increases with the increasing of the feed speed. Both the Zhang model and the beam theory model can predict the exit determination morphology. The beam theory model can reflect effectively the influences of the cutting speed and the feed speed on the exit delamination.