Koh 2015
Prepared for: Massachusetts Wind Working Group
September 30th, 2015
Rachel Koh
Ph.D. Candidate, University of Massachusetts Amherst
Advisors: Peggi Clouston, Bob Hyers, Matt Lackner
Bio-based Materials for Large Wind Turbine Blades
2 Koh 2015
Motivation for Large Wind Energy
4.13% of US electricity generated by wind in 2013
30% of all new generating capacity from 2009-2014
𝑃 =1
2𝜌𝐴𝑉3
Wind turbine rotor size trends from Fichaux (2011), DTU-Riso
3 Koh 2015
Basic Considerations for Blade Materials
Stiffness
• retain airfoil shape
• tower clearance
Strength
• tension, compression, bending
• fatigue
Density
• influences strength requirement
Hull, MA municipal wind turbine photo: R. Koh
4 Koh 2015
Concerns with fiberglass and carbon fiber
Fiberglass
• mass scaling
• recyclability / end-of-life disposal options
• global production increase from 5.9 million metric tons in 1999 to 8.7 million in 2011
• ~10% global fiberglass market share for wind energy and increasing
Carbon fiber
• expensive
• brittle
• energy intensive production
Blade Mass Scaling Relationships from NREL Cost and Scaling Model
5 Koh 2015
Advantages of Bio-Based Materials
Competitive specific stiffness and strength
Competitive fatigue properties
Ashby chart for Plant Fiber Reinforced Polymers from Shah (2013) at Oxford U.
6 Koh 2015
Advantages of Bio-Based Materials (cont’d)
Renewable (unlimited resource)
Biodegradable when triggered
Low emissions manufacturing
• EU- Directive on Landfill of Waste and End-of-life Vehicle Directive are seen as barriers for development and continued use of glass and carbon in some markets
Low cost raw materials
“Bio-inspired” and “Biomimicry” engineering
7 Koh 2015
Challenges with Bio-Based Materials
Variable mechanical properties
Limited experimental data for complex loading conditions such as off-axis and multiaxial loading
High sensitivity to moisture
Not fully developed manufacturing processes
8 Koh 2015
Current Projects
Shear Properties and Failure Mechanics of Angle-Ply Wood Laminate Beams
Yield Criteria Assessment for Multiaxial Wood Laminate and Flax Fiber Reinforced Composites
FEA of Wind Turbine Blades with Material Property Variability using Probabilistic Design
10 Koh 2015
Multidirectional Materials in Wind Turbine Blades
Adapted from Gurit Corporation (2014).
14 Koh 2015
Preliminary Torsion Test Results
0 5 10 15 20 25 30 35 40 45 500
100
200
300
400
500
600
Twist (degrees)
Torq
ue (
N-m
)
Torsion Test Results
angle-ply
unidirectional
Koh 2015
Yield Criteria Assessment for Multiaxial Wood Laminate and
Flax Fiber Reinforced Composites
18 Koh 2015
Multidirectional Materials in Wind Turbine Blades
Adapted with permission from Gurit Corporation (2014).
21 Koh 2015
Preliminary Results
0 0.2 0.4 0.6 0.8 1 1.2 1.40
10
20
30
40
50
60
crosshead displacement (mm)
str
ess (
MP
a)
0 degrees
30 degrees
45 degrees
60 degrees
90 degrees
22 Koh 2015
Preliminary Results (cont’d)
-20 -10 0 10 20 30 40-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5Biaxial Failure Envelopes for Several Composite Failure Criteria
1 (MPa)
2 (
MP
a)
Tension Tests
Compression Tests
Tsai-Wu
Tsai-Hill
Hoffman
Chamis
23 Koh 2015
Future Tasks
multiaxial flax composite tests
develop finite element material model to reflect multiaxial test data
finite element design of hybrid bio-based 5MW blades
24 Koh 2015
Acknowledgements
Committee: Professor Bob Hyers (MIE), Assoc. Professor Peggi Clouston (ECO), Assoc. Professor Matt Lackner (MIE), Adjunct Faculty John Fabel (ECO)
Undergraduate Students: Alex Finn (MIE ‘14), Jesse Turek (BCT ‘14), Charlie Tormanen (BCT ‘15), Malia Charter (Smith College ’16), Melody Cao (Smith College ‘16), Yashira Valentín Feliciano (University of Puerto Rico)
Funding source: NSF Offshore Wind Energy IGERT Grant Number 1068864