Advances in Fiberglass Properties for Wind Turbine Blades

Tom DeMint Marcus Liu Dave Hartman Georg Adolphs Richard Veit

Technical Marketing Composite Solutions Business

Owens Corning

Engineered Solutions

Copyright ® 2014 Owens Corning All Rights Reserved

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS Owens Corning is the leading producer of fiberglass

1938 1952 1970s 1980 1987 1996 2007

• Sales of $5.2 billion in 2013.

• 15,000 employees in 28 countries.

• FORTUNE 500 company for 59 consecutive years.

Owens Corning listed on NYSE

Owens Corning Fiberglas launched. $2.5M sales 600 people

$2 Bn sales $3Bn sales 18,000 people globally

Owens Corning purchases Saint Gobain becomes largest glass fiber producer

37 plants in 15 countries Inventor of all major glass types (E,ECR,S,R,H)

OC Reinforcements

OC Engineered Solutions

Composite Solutions Business ($2.5Bn)

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS Leading Innovation

Large capacity furnaces provide industrial supply of high performance glass fibers

Evolution of glass fiber innovation… • 1939: E-glass

– Boron added to glass for electrical properties

• 1965: R-glass (Higher performance)

• 1968: S and S-2 Glass®

– High strength and modulus (high melting power needed)

• 1974: AR-glass Alkali resistant

• 1978: E-CR Glass Corrosion resistant

• 1996: Advantex® ECR Glass and melting technology

– Boron free E-glass, ECR-glass (superior corrosion resistance to traditional E-glass) – Breakthrough in melting technology for large capacity furnaces

• 2006: R and H-glass melting technology

– Combines High modulus glass and Advantex®-scale melting technology

• 2009: S-glass direct melt large capacity technology

– Production in large capacity furnaces with higher fiber homogeneity

• 2014: Windstrand® product line Superior sizing chemistry

How OC Helps the Wind Energy Market

Working side-by-side with customers to develop new solutions

Leveraging our expertise for future growth

Fundamental product and process innovation to engineer advanced composites

6

Turbine Performance Trends in the Wind Energy Market

Market Evolution

Better reliability • 25 year blade life • 107 fatigue load cycles

ON-SHORE (LOW WIND) Longer blades to harvest energy in low wind speed regions and cold climates

ON-SHORE (HIGH WIND) Continued pressure to reduce capital/operating costs Requires cost effective solutions Reduce manufacturing and operating costs

OFF-SHORE Large turbines (8MW) larger blades (75m - 80m, glass, carbon) extreme environments

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS The Scaling Problem

• Aerodynamic loads scale up linearly with blade length, which of itself might not require an increase in material properties. • However blade mass, gravitational loads, and fatigue loads scale up exponentially with blade length.

Blade length

We

igh

t

Material requirements are increasing with increasing blade length and mass. Market needs higher Modulus/$, Strength/$

Material Data and Advances in Properties

New Products for Wind Turbine Blades: WS2000: Advantex® E/ECR-glass with advanced sizing for epoxy WS3000: High Modulus H-glass with advanced sizing for epoxy Ultrablade G3: WS3000 UD fabric (epoxy)

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS

Unidirectional Fiberglass Fabric/Epoxy Laminate Modulus Trend

Source: External test lab results 2009-2014 (IMA Dresden, WMC, TPI Composites); Momentive Epoxy resin L135/H137

Linear trend of increasing UD glass fabric modulus with increasing FVF approaching 50 Gpa using high modulus glass

Tweek 0.600.580.560.540.520.50

50

48

46

44

42

40

Fiber Volume Fraction

UD

La

min

ate

Ex,

GP

a,

Te

nsile

Advantex™ E

Windstrand™ H

Fiberglass type

UD/Epoxy Laminate Ex, GPa, Tensile vs Fiber Volume Fraction

800750700650600

1200

1100

1000

900

800

700

Compression Strength, MPa, 95/5% CI

Te

nsile

Str

en

gth

, M

Pa

, 9

5/

5%

CI

Advantex® E

Windstrand® H

Fiberglass type

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS

Longitudinal Modulus Ex, Measured vs. Theoretical

43210-1-2-3-4

99

95

90

80

70

60

50

40

30

20

10

5

1

Difference Measured-Theoretical Modulus E1 [GPa]

Pe

rce

nt

-0.2642 0.8623 9 0.427 0,241

0.04723 1.016 9 0.347 0,393

Mean StDev N AD P

ADV 78GPa

H 85GPa

Fiber

Normal - 95% CI

Source: IMA Dresden test results 2009-2014 on UD Fabrics, Momentive Epoxy resin L135/H137

210-1-2

5

4

3

2

1

0

Difference measured-theoretical

Fre

qu

en

cy

Mean -0.08867

StDev 1.004

N 22

Ex Measured- Ex Theoretical

Glass Bulk Modulus used for theoretical calculations Ebulk Advantex : 78 GPa Ebulk H-glass: 85 GPa

We observe good agreement between measured and theoretical longitudinal laminate modulus Ex

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS

UD/Epoxy Static Strength Properties, Characteristic Values (95%/5% Confidence Interval)

Source: IMA Dresden test results 2009-2014 on UD Fabrics, Momentive Epoxy resin L135/H137

We see a correlation between UD/epoxy tensile and compressive strength

800750700650600

1200

1100

1000

900

800

700

Compression Strength, MPa, 95/5% CI

Te

nsile

Str

en

gth

, M

Pa

, 9

5/

5%

CI

Advantex™ E

Windstrand™ H

Fiberglass type

800750700650600

1200

1100

1000

900

800

700

Compression Strength, MPa, 95/5% CI

Te

nsile

Str

en

gth

, M

Pa

, 9

5/

5%

CI

Advantex® E

Windstrand® H

Fiberglass type

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS

Laminate Behavior Transverse to the Longitudinal Fibers under Tension

Natural transverse contraction can be constrained by adjacent plies (often 90o plies) compared to a pure UD lamina.

This constraint may lead to limited transverse cracking, which may be acceptable in some rotor blades. However the average Inter Fiber Fracture strength (IFF) is measured and used for blade designs.

IFF cracks

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS Tensile Load Bearing Capability

Source: IMA Dresden test results 2009-2014 on UD Fabrics, Momentive Epoxy resin L135/H137

WS3000 “IFF Safety Factor” = 1.5

E-glass UD H-glass EPW17 WS3000

Low

er is better

15

Acoustical and Fracture Surface Analysis of Transverse 45deg Tension in Advantex/epoxy lamina panels

Source: OC WindStrand® fibers and data. Panels dry-wound roving and infused using Momentive epoxy L135/H137

E-glass UD/epoxy WindStrand UD/epoxy

Better fiber matrix adhesion leads to higher transverse strength

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS

Static Longitudinal Tensile Failure Modes, UD1800 SE1500 vs WS2000/epoxy

Source: OC test data UD1800 Fabrics, Momentive epoxy resin L035/038

UD WS2000/epoxy

UD E-glass/epoxy

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS Ultrablade® G3 vs G2 Fatigue Performance (Stress Amplitude)

Higher Initial Static Tensile Strength Leads to Longer Life

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 1 2 3 4 5 6

Ten

sile S

tren

gth

(M

Pa)

Tensile Strain (%)

Vintage E-Glass

State-of-Art E-Glass

S-Glass

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS

Strength Knockdown from Fiber to Laminate Damage Accumulation

Source: OC data on WS2000 UD Fabrics, Momentive epoxy R135/H137

0

200

400

600

800

1000

1200

1400

WS2000 Coupon Mean

UD1200 Coupon Mean

UD1200 Coupon R(95%)

UD1200 Spar Cap

Mean

Fatigue R=0.1

10^6 cycles

00 Tensile Strength 55%Vf (MPa) Knockdown

Better fatigue performance leads to longer life and lower design knockdowns from damage accumulation

Vintage E-glass Advantex® S-glass

Advantex®

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS

Fatigue Performance, Advantex® vs Ultrablade® UD Fabric/epoxy

6,05,55,04,54,0

700

650

600

550

500

450

400

350

LOG (N)

Pe

ak S

tre

ss [

MP

a]

ADV

H

Fiber

Source: Risoe / DTU tests 2013 on UD laminates, Momentive Epoxy resin L135/H137

Higher Initial Static Strength Leads to Longer Life

800750700650600

1200

1100

1000

900

800

700

Compression Strength, MPa, 95/5% CI

Te

nsile

Str

en

gth

, M

Pa

, 9

5/

5%

CI

Advantex™ E

Windstrand™ H

Fiberglass type

800750700650600

1200

1100

1000

900

800

700

Compression Strength, MPa, 95/5% CI

Te

nsile

Str

en

gth

, M

Pa

, 9

5/

5%

CI

Advantex® E

Windstrand® H

Fiberglass type

Fabric Handling

Molding Performance

Mechanical Performance

Blade Designer and Manufacturer Fitness-for-Use

• Increased longitudinal content

• “Steerable” UD fabric

• Unrolling characteristic SPC

• Short layup cycle time

• Smooth and aligned layup

• Suitable ply termination

• Efficient Infusion process

• Process Consistency

• Part Quality Consistency

Fitness-for-Use Characteristics Product Development Trend

• Reliable cycle time

• Reliable glass content

• Reliable part thickness

• 0o Tensile Modulus & Strength

• 90o Tensile IFF (Inter-fiber Fracture)

• Reliable Fatigue performance

• Polyester blades

• 50 GPa Longitudinal Modulus

•1200 MPa 0o static tensile strength

• Target IFF >90% matrix strength

• Fatigue target > 50% static @106 cycles

Many elements to the blade fabric FFU

21

Case Study of High Modulus Glass Fabric

Case Study: Application of Ultrablade® TRIAX G3 to Root Section

Ultrablade® TRIAX G3 fabric construction and modulus

Effect of fabric modulus on the blade root design

Infusion behavior

Wind Turbine Blade Root Connection Model (Samtech)

Single bolt and root laminate and bearing load modeled.

Root Connection Simulation Results

High Modulus Ultrablade® TRIAX reduces axial bold load by 17% which can increase bold fatigue life

E-glass fabric A E-glass Fabric B Ultrablade® TRIAX A Ultrablade® TRIAX B Ex = 28 GPa Ex = 30 Gpa Ex = 38GPa Ex = 42 GPa

Epoxy Resin Infusion Behavior

Area 9layers 19layers 29layers 39layers 49layers 59layers

Sample1-FWF 72.30% 72.20% 72.70% 72.80% 73.15% 73.38%

Sample2-FWF 72.35% 72.48% 72.52% 72.84% 72.98% 73.46%

Average FWF 0.72325 0.7234 0.7261 0.7282 0.73065 0.7342

Thickness 1.0998 1.0893 1.088 1.0882 1.0717 1.0716mm

mm

Ultrablade® TRIAX Commercialization

• Received first commercial order. 350 root sections.

• Published GL-certified independent testing reports

WINDSTRAND® REDEFINING OUR PLATFORM TO MEET EMERGING INDUSTRY NEEDS Summary

• External laboratories confirm consistent and reliable results for main design parameter (E, S, fatigue life) of current glass reinforcements and new products like WS3000 and Ultrablade® G3 fabrics.

– Similar linear best-fit slopes at higher initial static strength lead to longer life

• Glass reinforcements continue to offer a cost effective design solutions enabling longer and more efficient blades.

– We are pushing the UD glass/epoxy envelope, but we have not hit the upper limit of glass blade length.

– Ultrablade™ G3 fabrics offer a cost-effective alternative to carbon

• Since 2004, over 60 epoxy and polyester blades designs have been commercialized around the world using H-glass and Ultrablade®.

• We expect design values of 50+GPa for High Modulus UD glass/epoxy

Thank You

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