In April 2019, a wind turbine blade manufacturer in China successfully finished the production of an 87.5m spar cap. The spar cap is one of the key structures inside a rotor blade and takes up most of the mechanical load. The new record spar cap is made of carbon fiber to reduce the part’s weight and achieve higher stiffness which is essential for rotor blades of such extreme length.
The spar cap was designed by WINDnovation. It represented a technical challenge because of its length of 87.5m and its width of 800mm. Materials used for production of the part were the Saertex infusion-optimized carbon fiber UD 618gsm (unidirectional non-crimp fabric) with increased z-permeability material, which had been specially developed for the infusion of thick lay-ups as well as the latent resin system 3325 A/B from CTP AM with optimized viscosity and extended pot-life.
The spar cap was infused in VAP technology with Composyst’s VAP membrane CS/E which enables degassing of the resin during the entire infusion and eases resin distribution throughout the entire part as well as control of the resin content in the part. This makes the entire process safer.
The infusion process itself took less than 2 hours and was completed without any problems. After demolding, the entire team was very pleased to inspect a spar cap of virtually perfect built quality. The prototype production was technically supported by Saertex, WINDnovation, Composyst and CTP AM.