CompositesWorld
Issue link: https://cw.epubxp.com/i/930524
NEWS CompositesWorld.com 35 FIG. 7 Static and fatigue testing Static (top photo) and fatigue (bottom photo) full-scale testing confirms design loads. Flapwise and edgewise loads were generated on the blade using a mechanical exciter, the same principle used during all other LM tests. But in the case of the LM 88.4 P blade, the test regime was beyond what LM had ever attempted in the past. Its lab first had to scale up the test equipment and review and confirm the standard test procedures for the big blade. FIG. 8 Transport by truck and barge The blades' massive size presented some significant challenges in terms of transportation. Movement was limited to after heavy road traffic hours. Each 60-ton blade made the 218-km trek through Denmark late at night by truck to Aalborg, Denmark (top photo). From there, they were carried by barge (bottom photo) to their final destination in Bremerhaven, Germany. • Part is cured at room temperature, according to proprietary LM specifications. • After cure, the base shell is de-bagged and inspected to prepare it for the next stage. In the second stage, the hybrid main spar cap is then built up on top of the cured base shell, using the cured shell as a mold: • Hybrid UD carbon/glass fabric layers are applied directly over the base shell, starting 4m from the root. • LM-designed lightning protection components are added. • Standard ±45° biaxial fiberglass coverage layers are arranged. • Vacuum bag and VARTM infusion, carefully controlled to infuse only the carbon layup with a specially developed resin system. • Part is cured at room temperature, according to proprietary LM specifications. "We were able to scale-up our standard manufacturing process for our increasingly long blades," Lund-Laverick says. On these huge blade halves, the sides curve up but the center of the struc- ture is essentially flat," he adds, "with only a gentle curve in the length direction due to pre-bending of the blade." For the flat sections of the blade halves, LM's in-house-designed, computer- controlled, semi-automated machine lays down wide sheets of dry fabric in programmed layers to meet strength requirements. Carbon/Glass Spar Cap