In June 2017, a major Chinese wind turbine blade manufacturer successfully finished the production of an 83.6 m blade prototype. A special feature of this blade is its spar cap, which takes up most of the mechanical load. The spar cap is made of carbon fibre to reduce the part’s weight and achieve higher stiffness which is essential for blades of such extreme length.
The blade was designed by WINDnovation. Its spar cap was pre-produced in May and represented a technical challenge because of its length of 80.5 m and thickness, at its broadest section, of 70 mm.
A SAERTEX infusion-optimised carbon fibre UD 618 gsm (unidirectional non-crimp fabric) with increased z-permeability material was used, which has been specially developed for the infusion of thick lay-ups. The resin system 3325 A/B from CTP AM is said to deliver optimised viscosity and extended pot-life.
The spar cap was infused using VAP technology with Composyst’s VAP membrane which is said to enable degassing of the resin during the entire infusion, ease resin distribution throughout the entire part, as well as control the resin content.
The infusion process took less than 3 hours and was completed without any problems. The following day, after curing and demoulding, inspection found a near perfect part free of defects, SAERTEX reports. The prototype production was technically supported by SAERTEX, WINDnovation, Composyst, CTP AM and ITD.