Synthesis, fabrication and mechanical characterization of reinforced epoxy and polypropylene composites for wind turbine blades

Failure of wind turbine blades usually originates from manufacturing defects or in-service defects. In this study, materials selection for manufacturing of wind turbine blades was carried out based on the mechanical and physical results obtained using the Cambridge Engineering Selector program. Thermoplastic and thermosetting composites were synthesized and processed using injection molding and vacuum assisted resin infusion techniques, respectively. Operating conditions (vacuum pressure and temperature) were optimized. The manufactured samples were tested and evaluated using destructive tests. Tensile and fatigue tests were carried out. Polypropylene random discontinuous glass fiber composites were synthesized and processed using mold injection technique. Epoxy-carbon, glass and carbon/Kevlar hybrid fiber composites were manufactured using vacuum assisted resin infusion technique. Surface morphology was characterized using scanning electron microscope analysis. Tensile strength and fatigue resistance were significantly improved by the presence of E-glass fiber (30wt%) in polypropylene-glass fiber composites. The experimental results were compared with the Cambridge Engineering selector software database. Epoxy-carbon (carbon fiber fraction is 0.61) and carbon/Kevlar hybrid (fibers fraction is 0.6) composites showed superior mechanical properties. Epoxy/carbon composite can withstand stresses up to 1390MPa at 10(6) cycles.