A comprehensive investigation of drilling performance of anisotropic stacked glass-carbon fiber reinforced hybrid laminate composites

Among the various renewable energy sources, wind energy offers an effective solution to the energy providers. Onshore wind turbines are generally designed for sites with low wind resources, while offshore wind turbines can be more efficient in producing energy thanks to their longer blades that provide more than 10 MW of rated power. Offshore wind turbine blades are subjected to significantly higher stresses and harsh environmental conditions. Therefore, hybrid composites composed of carbon and glass fibers can offer cost-effective and long-lasting solutions for wind turbine blade manufacturers. Turbine blades are connected with main spars through bolted connections and high interlaminar stresses occurring during the drilling process can cause to delamination in the composites. To prevent catastrophic failure related to defective machining, the drilling process must be performed meticulously and all machining-related results must be analyzed step by step. In this paper, dry drilling properties of hybrid glass-carbon fiber laminate epoxy matrix composites were examined experimentally in order to contribute to the wind energy sector. The results showed that the delamination factor could be decreased with higher cutting speeds or lower feed rates. Besides, higher feed levels caused higher thrust forces on the tool body.