Static Performance Assessment of Recyclable Bio-Based Resin for Wind Turbine Blades Using Sub-Component Testing

Abstract

Bio-based resin systems are attractive for use in wind turbine blade manufacturing because they offer opportunities for recycling at the end-of-life of the blade and an environmentally friendly alternative to the currently used epoxy-resin systems. However, before any bio-based resin can be used in blades, its structural and fatigue performance must be determined to be as good as or better than the currently used epoxy resins. Certification of new material systems for utility-scale wind turbine blades starts with coupon testing of the materials and culminates with the full-scale testing of the blade. Coupon testing is not necessarily fully representative of the structural performance of the blade and full-scale testing is costly, time consuming and labor-intensive. Subcomponent testing has the potential to bridge the gap between the coupon and the full-scale testing and to facilitate and expedite the introduction of new material systems into the blade manufacturing industry. In this paper, two sets of scaled-down composite I-beams representing the spar cap and the shear web geometry of a utility-scale blade are designed and manufactured. One set is made from a conventional epoxyresin system, and the other set is made using a recently developed bio-based resin system. The beams are loaded in a quasi-static four-point bending test configuration, and the strain fields of their flanges are measured using digital image correlation. The strain fields of the beams made of the conventional resin system are compared to their counterpart bio-based beams. The results show a comparable flexural stiffness for the bio-based resin beams to the conventional-resin beams.