Conclusion
Delamination during the drilling of a carbon-epoxy composite

The results of the proposed numerical model for predicting the critical thrust forces responsible for delamination at the hole exit were compared with the measured critical thrust forces and those obtained by analytical models based on the assumption of an orthotropic material and a circular crack. The critical forces predicted by this numerical model are driven by the energy restitution rates in Mode I and Mode II, and not only by Mode I as assumed by the analytical models