Mechanical characterization and evaluation of delamination of polymer composite laminate

Drilling-induced delamination is an inter-ply failure phenomenon and has been recognized as the most common defect during drilling of carbon fiber reinforced polymer (CFRP) composites. In the present work, an attempt has been made to study the influence of process parameters (spindle speed, feed rate, point angle and drill diameter) on delamination in drilling of uni-directional carbon fiber reinforced polymer (UD CFRP) composite using high speed steel (HSS) and titanium nitride (TiN) coated solid carbide drills. Taguchi L₂₇ orthogonal array is employed for investigating the effects of process parameters on delamination. The genetic algorithm optimized multi-layered perceptron neural network (GA-MLPNN) and response surface methodology (RSM) are used for predicting drilling-induced delamination. The experimentally determined mechanical properties of UD CFRP composite are validated by using finite element method (FEM). The investigation shows that the experimental and the FEM validated results of mechanical properties are in good agreement. The results indicate that drill diameter has a significant influence on delamination, followed by spindle speed and feed rate. It is evident from the study that the TiN coated solid carbide drills are the preferred choice than HSS drills in reducing the drilling-induced delamination.