Combatting rain erosion of offshore wind turbine blades by co-bonded thermoplastic-thermoset hybrid composites

An integrated thermoplastic-thermoset hybrid leading edge protection system is developed based on the co-bonding process. Co-bonding is a joining method in which a prefabricated part joints with a thermoset composite during the curing process. In such a multi-material hybrid design, the reliability of the bonding between the prefabricated protection layer and the main body of the blade is of crucial importance to prevent any delamination failures. Nevertheless, the adhesion of prefabricated thermoplastics to the thermoset remains a challenge as the interphase between two dissimilar materials is prone to form defects and irregularities. Such interface defects may lead to early failure and reduced structural integrity of the components. Therefore, the focus of this study is on achieving a strong, and reliable bonding between the prefabricated thermoplastic leading edge protection system and thermoset main body of the blade. In this study, the effect of processing temperature on the interphase quality and thickness during the co-bonding process is investigated. Next, mechanical characteristics and microstructure of the interphases are examined by Vickers microhardness tests. The effect of processing condition on the fracture toughness of structure is examined by climbing drum peel tests (CDP). Finally, fractography investigations are used to provide an understanding of failure mechanisms and its correlations with interphase morphology and microstructure.