Influence of inclined holes on the impact strength of CFRP composites

The objective of this work is to study the effect of inclined holes on the impact strength of carbon-fibre reinforced composites. For this purpose, plates with vertical and inclined holes were tested under low velocity impact and the respective results were compared with control samples without hole. It was observed that inclined holes promote lower maximum loads and higher displacements, which can be justified by the damage mechanisms associated to stress concentration. In fact, the damage becomes asymmetric and increases with hole inclination, as a consequence of change of stress field profile. A complex damage mechanism based on interaction between matrix cracking and delamination was identified. A three-dimensional numerical model based on cohesive zone modelling was developed to deal with damage mechanism and influence of inclined holes. It was concluded that it is crucial to account for matrix cracking to achieve a good prediction of delaminated area. The experimental trends concerning hole inclination were well captured by the model.