Drilling analytical model of composite material with pilot hole
Résumé
The use of composite materials machining is increasing more and more in aeronautical. Drilling process is in particular the most used process in the assembly of aeronautical structures. When drilling thick composite laminates, delamination occurs at the exit of the hole. These defects are assumed to be the major defects. They diminish the strength of the structure to failure. To minimize delamination, drilling process with pilot hole is used. In this paper, analytical model for drilling thick composite structures with pilot hole using a twist drill is proposed. This model predicts the critical thrust force at delamination. Different hypotheses of boundary conditions and external loading are proposed. Numerical model is also developed in order to validate the proposed analytical model. Punching tests with twist drill are then realized in order to select the corresponding hypothesis of boundary conditions and external loading. These results may be used to optimize the cutting conditions when drilling thick composite plates with pilot hole.