Experimental study and optimization of effective drilling parameters on fibers glass–epoxy composite

Drilling process of Fibers Glass-epoxy composites is always associated with defects such as interlayer delamination phenomenon. This phenomenon reduces the strength of composite panels. In this study, to minimize this defect, the effective parameters including feed rate, tool diameter, thickness, edge tool angle, rotational speed, orientation fibers and coolant were studied. The number of experiments was specified based on Taguchi's design of experiments method and Experimental study was performed on the drilling process of the composite to evaluate the amount of delamination. Then holes were scanned by a Video Measuring machine(VMM) and amount delamination in them has been calculated by considering hole diameter. The collected data were used to statistically analyze and optimize the drilling parameters using variance analysis (ANOVA). The results showed that feed rate with a 29.6% and rotational speed with 24% had greatest influence on the delamination, so that with increasing the feed rate delamination was increased and with increase in rotational speed, delamination is first increased and then decreased. Also to investigation of the effect of delamination on the tensile strength of composite and stress concentration coefficient, specimens were subjected to tensile test. The results showed that with increasing delamination, the average tensile strength and stress concentration coefficient of perforated parts compared to healthy specimen( without hole), 34% decreased and 51.66% increased respectively. Also with 1.22 times the delamination compared to the delamination of initial sample, tensile strength 6.5% decreased and stress concentration coefficient 6.9 increased.