Experimental analysis of GFRP laminates subjected to compression after drilling

This paper presents an experimental study of drilling-induced delamination on the compressive properties of woven glass fiber-reinforced epoxy composites. In the drilling of laminated composites, interlaminar cracking or delamination has a detrimental effect on compressive properties. The onset of delamination and the extent of the damage are governed by the cutting forces developed during the drilling process. High cutting forces, in turn, result from the use of improper drilling parameters. This study investigates the effects of feed rate and spindle speed on delamination and residual compressive strength. The composite laminates were cut into the standard dimensions of compression after impact specimens. The drilling of composite specimens was conducted at three different levels of spindle speed and feed rate based on general full factorial design. Analysis of variance was used to find the percentage contribution of the drilling parameters and it was found that feed rate has the most significant influence on the residual compressive strength. A polynomial regression model was also developed to express the residual compressive strength as a function of the selected process parameters.