Revised adjusted factor for delamination measurement in drilling of composites

Delamination, an inter-ply damage, is a major concern during the drilling of FRP composites. It is evident from past studies that the focus of the researchers has been mostly on reducing the delamination damages by optimising the input parameters, cutting parameters, tool geometry parameters and work materials properties, rather than improving the model for quantifying the delamination factor to get near-to right values. Though Davim’s adjusted model overcomes the demerits of mostly proposed models, it is believed to give the exaggerated values of the delamination factor. Thus, the present study proposes a revised basic two-dimensional model to quantify the delamination factor for fibre-reinforced polymer composites, while addressing the exaggeration effect caused by the most commonly used adjusted delamination factor model. The developed model in this work resulted from combining two prior stated models: Davim’s adjusted model and Da Silva's minimum delamination factor model. The proposed model is validated experimentally and reconfirmed with additional experiments concerning its applicability and efficacy. The delamination damage in this work is characterised by the peel up mechanism for the experimental validation purpose. The results indicate that the exaggeration effect is reduced by 13 to 15% in determining delamination factor value using the proposed model, compared to the existing two-dimensional adjusted factor model.