Upper (LP)
Spar Cap
Sandwich Shell Sandwich Shell
Trailing Edge
Leading Edge
Sandwich Shell
LE Shear
Web
TE Shear
Web
Sandwich Shell
Lower (HP) Spar Cap
2

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

Figure from GE

• 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”

UTS
Glass/X
Glass/poly ester
Carbon/e poxy
Birch/epo xy
880
700
1830
117
UCS
720
580
1100
81
UCS/sg
390
310
700
121
Fatique % of UCS
19
21
Stiffness/ sg
20
18
E/UCS^2
.07
.1
32 90 .12
20 22 2.3
Steel: fatigue and mfgblty

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

April 15, 2020 Courtesy: Nolet, TPI 8

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

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

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

• Matrix (primary phase)
– Polymer, metal, or ceramic
• Reinforcing agent (imbedded phase)
– Polymer, metal, ceramic, or element
– Fibers, particles, . . .

Metal
Ceramic
Polymer
Element
Metal
PM infiltrate w/ 2 nd metal
Cutting tool
PM part w/ polymer
Fiber reinforced metals
Matrix
Ceramic n/a
SiC in Al
2
O
3 n/a n/a
Polymer
Steel belted tire
‘fiberglass’
Kevlar reinforced epoxy
Carbon fiber reinforced polymer

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

• Short fibers:
– Open mold: spray up
– Closed mold processes
• Long fibers:
– Open mold: hand, automated tape machines
– Closed mold
– Filament winding
– Pultrusion

• Polymer matrix
– Thermosets: most common
– Thermoplastics
• Reinforcing
– Glass
– Carbon
– Kevlar (polymer)

• 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

• 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

• 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

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

• 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

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

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

Source: www.tpicomposites.com 3/2008

Source: www.tpicomposites.com 3/2008

Source: www.tpicomposites.com 3/2008

® 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)
April 15, 2020 Courtesy: Nolet, TPI 28

• 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.
Courtesy of Saertex USA
Courtesy: Nolet, TPI 29 April 15, 2020

• 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
April 15, 2020 Courtesy: Nolet, TPI 30

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

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

• 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

• 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

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

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

Mark Higgins 9/15/2011 Presentation at ISU

Mark Higgins 9/15/2011 Presentation at ISU

Mark Higgins 9/15/2011 Presentation at ISU

Mark Higgins 9/15/2011 Presentation at ISU

Mark Higgins 9/15/2011 Presentation at ISU

Mark Higgins 9/15/2011 Presentation at ISU

• Maintain +-mm across
50m assembly
• Joints are critical
43

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 http://mag-ias.com/index.php?id=308&L=2

• Manufacturing
– Make at point of use
– Make in region of use
– Import
• Design
– Flatback design
– Design in 2 pieces
– Materials to reduce weight

Remote Blade Manufacturing Demonstration –
Sandia 2003