2. Blade with Shear Web bonded to Spar Cap Sandwich Shell TE Shear Web LE Shear Web Trailing Edge Sandwich Shell Lower (HP) Spar Cap Upper (LP) Spar Cap 2 Leading Edge

3. Source:http://www.compositesworld.com/articles/wind-blade-manufacturing-targeting-cost-efficiency- through-materials-based-strategies.aspx 4/5/2009

4. Blade Objectives Figure from GE

5. Blade Objectives Maximize annual energy yield (limit maximum power) Resist extreme and fatigue loads Restrict tip deflections Avoid resonances Minimize weight and cost Burton, Sharpe, Jenkins, Bossanyi: “Wind Energy Handbook”

6. UTSUCSUCS/sgFatique % of UCS Stiffness/ sg E/UCS^2 Glass/X8807203901920.07 Glass/poly ester 7005803102118.1 Carbon/e poxy 183011007003290.12 Birch/epo xy 1178112120222.3 Steel: fatigue and mfgblty

7. Blade Materials compressive strength-to-weight ratio, fatigue strength as a percentage of compressive strength, stiffness-to-weight ratio, a panel stability parameter, E/(UCS)2.

8. May 13, 20158 Courtesy: Nolet, TPI

9. Power, Length and Weight Burton, Sharpe, Jenkins, Bossanyi: “Wind Energy Handbook”

10. Polymer Matrix Composites & Processes

11. General Composite Information Composites: 2 or more physically distinct phases Properties are better than the constituents High strength to weight ratio Also.. Corrosion, fatigue, toughness, surface finish

12. Why nots... (many have) anisotropic properties Polymer based may be subject to chemical attack Cost? Manufacturing process often slow and costly (Groover p 177)

13. 2 or more phases Matrix (primary phase) – Polymer, metal, or ceramic Reinforcing agent (imbedded phase) – Polymer, metal, ceramic, or element – Fibers, particles,...

14. Possible combinations for 2 phases Matrix MetalCeramicPolymer Reinforcement MetalPM infiltrate w/ 2 nd metal n/aSteel belted tire CeramicCutting toolSiC in Al 2 O 3 ‘fiberglass’ PolymerPM part w/ polymer n/aKevlar reinforced epoxy ElementFiber reinforced metals n/aCarbon fiber reinforced polymer

15. Fiber reinforcement Diameters of 0.0001 to 0.005 inches As D ↓, orientation ↑, probability of defect↓ – tensile strength↑ ↑ Orientation: – Unidirectional, planar, 3 dimensional

16. Fiber Reinforced Polymer Composites Short fibers: – Open mold: spray up – Closed mold processes Long fibers: – Open mold: hand, automated tape machines – Closed mold – Filament winding – Pultrusion

17. Materials Polymer matrix – Thermosets: most common – Thermoplastics Reinforcing – Glass – Carbon – Kevlar (polymer)

18. Composing Composites... Molding compounds – Mix short fibers and matrix Prepegs – Fibers impregnated with partially cured TS matrix – Allows fibers to ‘stay put’ – Continuous fibers Or done in the mold

19. Open Mold Process Spray up – Requires mold – Discontinuous fibers // random orientation – Mixture of fiber and matrix deposited in mold Automated tape laying machine – Requires mold – Requires use of prepeg – CNC control Image sources: http://www.bauteck.com/manufacture/Manufacture2.htm 4/5/9 http://www.mmsonline.com/articles/getting-to-know-black-aluminum.aspx 4/5/9

20. Filament Winding Wound around mandrel or part of final component Continuous fibers – Matrix added before or after winding Automation controls wrap pattern Source:http://sacomposite.com/filament_winding_carbon_fiber. html 4/5/9

21. Pultrusion Continuous fibers Dipped into matrix 2 options: – Pulled through die and cured – Laid up into an open mold (and later cured) Source: http://www.ale.nl/ale/data/i mages/Pultrusion.jpeg 4/5/9 http://www.tangram.co.uk/TI-Polymer-Pultrusion.html

22. Open Mold Processes Hand lay up – Oldest, labor intensive – Mold required – Fibers placed in mold: Dry fibers placed and then matrix added – Pour or brush or spray >> rolled to achieve mixture – Vacuum used to ‘pull’ matrix into fiber Prepeg placed in mold

23. Burton, Sharpe, Jenkins, Bossanyi: “Wind Energy Handbook”

25. Source: www.tpicomposites.com 3/2008

28. Reusable Silicon Bag Technology for SCRIMP ® May 13, 201528 o Silicone bags are rapidly fitted to the infusion tool o Feed lines, vacuum lines and embossed distribution channels are integrated into the bag improving the repeatability of the process (TPI Patented Technology) Courtesy: Nolet, TPI

29. Fibers Woven Fabrics – Higher cost, less applicable as structural components for blades Non-woven Multiaxials – Most widely used in VARTM processes – Low-cost, non-crimp form results in superior performance – “Uni-directional”, Biaxial, Double Bias, Triaxial and Quadraxial material forms available. May 13, 201529 Courtesy of Saertex USA Courtesy: Nolet, TPI

30. Resin Matrices Epoxies remain a primary resin of use in European based blade designs Vinyl-esters are attracting much interest by blade designers Polyester resins are still prominent in the industry. Thermoplastics and other matrices May 13, 201530 Courtesy: Nolet, TPI

31. http://www.compositesworld.com/articles/carbon-fiber-in-the-wind.aspx

32. Blade Components Infused Together Skin – Composite – Core Spar cap – Composite Shear web – Composite – Core Root Section – composite Other Materials Bond paste Hardware Balance box Paint Lightening protection system Platform

33. Quality Issues Waves – Aspect ratio (L/a) Bond failure Dry infusion Lack of continuous fibers Geometrical errors Fabric assembly errors Figures from: “Yerramalli, Miebach, Chandraseker, Quek: “Fiber Waviness Induced Strength Knockdowns in Composite Materials Used in Wind Turbine Blades”. 2010

34. Process Steps Cut fabric Preforms – Layup – Infuse – Inspect – Trim Shell – Layup – Install preforms – Infuse Assembly – Shear web – 2 shells Finishing – Finish edges – Wet layup Final cure Drill and cut end square Finishing and painting Hardware Balance box Final inspect

35. Burton, Sharpe, Jenkins, Bossanyi: “Wind Energy Handbook”

37. Mark Higgins 9/15/2011 Presentation at ISU

43. Assembly Variation 43 Maintain +-mm across 50m assembly Joints are critical

44. http://mag-ias.com/index.php?id=308&L=2 Rapid Material Placement Systems (RMPS) Automated blade molding Automated root end machining for wind blades Machine adapts automatically to blade position Machining processes: Sawing, milling, boring and trimming Future Automation Systems?

45. Options for Large(r) Blades Manufacturing – Make at point of use – Make in region of use – Import Design – Flatback design – Design in 2 pieces – Materials to reduce weight

46. Remote Blade Manufacturing Demonstration – Sandia 2003