Process Development Issues of Glass-Carbon Hybrid-reinforced Polymer Composite Wind Turbine Blades

Large structures made with composites (e.g., wind turbine rotor blades, yachts, and airplane fuselages) employ fabrics with small tow sizes especially when fabricated by vacuum-assisted resin transfer molding (VARTM). Simulation tools are frequently used to aid the manufacturing process development for large structures. This article details the development of a low cost VARTM manufacturing process for a 3.2 m long aeroelastically tailored rotor blade that has been completed without an infusion modeling tool. This robust VARTM-based process has been developed for very large tow sized fabrics with very poor permeability. Changes in the manufacturing process are made based on a parametric matrix until the desired part quality is achieved. Principal in-plane permeability is measured using 1D channel flow method for various fibers used in this study. Details of the methods employed to assemble the final blade are presented. The final process results in the fabrication of six rotor blades each with different lay up and fiber constituents. Problems and solutions related to migrating from a small-scale VARTM process to larger structures are detailed. Final blade quality is determined by full-scale mechanical testing under static and fatigue loading conditions. All the manufactured blades fail at least 160% above the proof load indicating compliance with the design quality criteria.