The complex cutting edges of the drill bit and different machinability properties of novel hybrid fibre-reinforced polymer (FRP) composites make it challenging and difficult to obtain consistent and damage-free holes. While the findings presented in previous literatures have shown that the desired drilling parameters are feasible for minimization of delamination damage, the changing in the thrust force is known to play a critical role in influencing the size of the delamination zone. In order to elucidate the mechanism of drilling-induced delamination for hybrid FRP composites, an analytical study of drilling characteristics for this novel material has been attempted. This analytical model was established based on the principle of virtual work (energy balance equation), linear elastic fracture mechanics, classical plate bending theory, and the principle of rule of mixture. Results of this analytical study indicate that the delamination damage can be alleviated if the applied thrust force is lower than the critical thrust force value. The applied thrust force and delamination damage from experimental results were used to validate the proposed model. A good agreement between the estimated critical thrust force and the measured thrust force was evident in this particular study.
