Prediction of critical thrust force for exit-ply delamination during drilling composite laminates: Thermo-mechanical analysis

Drilling damage, such as delamination at the hole exit, is known to adversely affect the load carrying capability of a structure resulting in reduced endurance limits and overall reduction in structural integrity. In this context, the present work studies the influence of temperature of machining on the critical thrust force responsible for delamiantion at the hole exit. An analytical model considering thermo-elastic field equations has been established with the aim of predicting the critical thrust force. The validation of this model has been conducted at room temperature via punching tests carried out on carbon fibre epoxy multi-directional composite laminates. Some difference in predictions exists which are mainly attributed to the variability in ply thicknesses due to the manufacturing process. Such an analysis underscores the need to explicitly account for machining temperature effects on machining damage characterisation.