New analytical model for delamination of CFRP during drilling

Franck Girot (1, 2) , Frédéric Dau (3) , Esther Gutierrez-Orrantia (1)

1 UPV / EHU - University of the Basque Country = Euskal Herriko Unibertsitatea
2 Ikerbasque - Basque Foundation for Science
3 I2M - Institut de Mécanique et d'Ingénierie de Bordeaux

Drilling of composite material structure is a widely used process in aeronautical assembly due to its best manufacturing value (ratio quality/cost). However, delamination which can be generated at the hole exit is still a problem and is directly related to the drill axial force, the composite material mechanical characteristics and the load distribution along the cutting and chisel edges. This paper analyzes the distribution of the load along the drill edges and points out a triangular distribution associated to an additional load located at the centre of the drill. This additional load depends strongly on the feed rate. An orthotropic analytical model is then proposed in order to determine the delamination critical thrust during drilling for different combined loadings. This new model is compared with the existing ones in the literature and with experimental results. This analysis highlights that delamination occurs in a mixed mode and not in mode I only. The use of the B-K criterion for the determination of the equivalent critical energy release rate GC and a cutting edge combined loading (triangular distribution associated to an additional load) allow a close correlation between experimental measurements and the prediction of this new model.

Mots clés: Carbon fiber reinforced polymer; Delamination; Analytical modelling; Machining

Domaines: Physique [physics]

Franck Girot, Frédéric Dau, Esther Gutierrez-Orrantia. New analytical model for delamination of CFRP during drilling. Journal of Materials Processing Technology, 2017, 240, pp.332-343. ⟨hal-02333106⟩