The document discusses 1) assessing cost savings from optimizing a wind turbine blade made with Ultrablade fabrics instead of Advantex fabrics, and 2) developing a coupled fatigue analysis method. It describes creating blade FEM models, optimizing laminate stacking sequences, integrating the blade model into a wind turbine mechatronic model, and analyzing intra-laminar fatigue at hot spots directly using the coupled model. Preliminary conclusions found the Ultrablade blade has higher cost savings and similar strength and fatigue life as the Advantex blade. The new fatigue method allows analyzing stress-strain cycles directly from the coupled model instead of additional local analyses.

1. Wind Turbine Blade optimization
and Advanced Fatigue analysis
SAMTECH Ibérica:
José Luis Sánchez, Paul Bonnet, Andreas Heege
Owens Corning, Composite Solutions Business
Georg Adolphs, Paul Lucas

2. Goals
1. Assessment of the cost savings achieved thanks to
the use of the Ultrablade® Fabrics UD material
instead of the Advantex® UD material by optimizing
the distribution and number of UD plies and by
comparing the blade’s behavior in terms of stiffness,
strength and fatigue
2. Development of a fatigue method that allows counting
the cycles of stress / strain directly in the Wind
Turbine mechatronic model by avoiding the use of
further time consuming and uncoupled local fatigue
analysis (linear superposition, modal superposition,
random fatigue)
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3. Tasks Index
1. Blade Aerodynamic surfaces creation
2. Adv.-Blade and Ultra.-Blade detailed parametric
FEM creation and optimization
3. Wind Turbine Mechatronic model creation and
blade integration
4. Intra-laminar fatigue analyses according to the
proposed coupled fatigue method and the GL and
DNV Goodman diagrams
5. Conclusions
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4. Aerodynamic Geometry
2D Aerodynamic Airfoils
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5. Aerodynamic Geometry
Blade Length [m]
Chord length
distribution
Chord Length [m]
Z
Y
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6. Aerodynamic Geometry
Blade Length [m]
Wind
Thickness [m]
Z
X
Thickness distribution
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7. Aerodynamic Geometry
Blade Length [m]
X
Y
Twist angle [º]
Wind
Twist distribution
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8. Aerodynamic Geometry
Blade Length [m]
Wind
Distance with respect to pitch axis [m]
Z
X
Pre-bend
distribution
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9. FEM creation and optimization
A1, A2, from
1m to max.
chord
A1, A2, from
max. chord to
39.5 m
B1, B2, from
1m to max.
chord
B1, B2, from
Triax 1 Triax 2 UD PM45 FOAM Adhesive max. chord
to 39.5 m
C1,C2, D1,D2
A1 C1 from 1m to
B1
max. chord C1,C2,
D1
D1,D2 from
max. chord
G
to 39.5 m
B2
E1 – E2
C2
F G
A2
D2
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10. FEM creation and optimization
2 PLIES OF TRIAX
FROM 60 TO 1 PLY OF TRIAX
stacking laws showing variations of #2 and #3 laminates.
n Plies of UD (NPMAX_1 parameter)
LA1 LB1
FOAM (max. thickness = 15mm)
n Plies of UD (NPMAX_3 parameter)
LA3 LB3
2 PLIES OF TRIAX
A1 C1
B1 1 PLY OF ADHESIVE
D1
G
B2 2 PLIES OF PM45
C2
A2
D2 Span length
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11. FEM creation and optimization
Automatic Optimization in BOSS QUATTRO
2 PLIES OF TRIAX
Objective = Mass Reduction
stacking laws showing variations of #2 and #3 laminates.
FROM 60 TO 1 PLY OF TRIAX
Constraints = 1st Flap & 1st Edge frequencies
n Plies of UD (NPMAX_1 parameter) have to remain the same as for the baseline
Parameters:
LA1 LB1
FOAM (max. thickness = 15mm) LA1: length where number of sparcap UD plies
(zones A1-A2) increases from 0 to max.
n Plies of UD (NPMAX_3 parameter)
LB1: length where number of sparcap UD plies
LA3 LB3 (zones A1-A2) decreases from max. to 0.
2 PLIES OF TRIAX NPMAX_1: max. number of sparcap UD plies
(zones A1-A2)
1 PLY OF ADHESIVE
LA3: length where number of trailing-edge UD
plies (zones B1-B2) increase from 0 to max.
2 PLIES OF PM45
LB3: length where number of trailing-edge UD
plies (zones B1-B2) decrease from max. to 0.
NPMAX_3: max. number of trailing-edge UD
plies (zones B1-B2)
Span length
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12. FEM creation and optimization
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13. FEM creation and optimization
ULTRA.-BLADE ULTRA.-BLADE
Spar-Cap stacking laws Trailing-Edge stacking laws
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14. FEM creation and optimization
ULTRA.-BLADE: Objective and constraints variation during iterations
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15. WT Mechatronic model &
Blade integration
Gravity
Aerodynamic
loads
Using BEM
Theory
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16. GE25 GEN1 High Fidelity Mod
WT Mechatronic modelof& Number Nodes
BUSHING
Number of elements Type : 75 81 Number of elements Type :
Blade integrationof Elements
Elements
Number
HINGE
Number of elements Type : Number of elements Type : Rigid Bodies
78 25 72 41 Number of elements Type :
Elements
DAMPER DIST
Number of elements Type : Number of elements Type :
108 9 74 1 Number of elements Type :
Elements Elements
FEM
GEAR BUSHING
Number of elements Type : Number of elements Type :
113 15 75 81 Number of elements Type :
Elements Elements
Number of Degrees of Freedom
Number of elements Type : 78
MBS
25 Rigid Bodies
DAMPER
Number of elements Type : 108 9
Elements
Control
GEAR
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Number of elements Type : 113 15

17. WT Mechatronic model &
Blade integration
Samcef for Wind Turbines (S4WT)
mechatronic model
Gravity
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18. WT Mechatronic model &
Blade integration
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19. WT Mechatronic model &
Blade integration
n Master nodes
Slave & master nodes are linked through
«weighted constraint equation»:
Φ=∑ αi (Umaster_i - Uslave) =0
1 Slave node
The individual «constraint factors»:
αi (Umaster_i - Uslave) αi (Umaster_i - Uslave)
correspond ideally to the «real» pressure
distribution of the outer blade skin
The resulting blade stress
distribution is strongly depended
on the choice of the weights αi
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20. WT Mechatronic model &
Blade integration
Reverse engineering AEROMAPPING procedure
EXTRADOS
Pressure [KPa]
3 1.7 0.4 -0.9 -2.2 -3.5 -4.8 -6.1 -7.4 -8.7 -10
INTRADOS
AEROMAPPING: Blade pressure field
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21. WT Mechatronic model &
Blade integration
TSAI-WU DISTRIBUTION
Aeromapping
TSAI-WU DISTRIBUTION
15 discrete aerodynamic
Differences lower than 10%
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22. Intra-laminar Fatigue analysis
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23. Intra-laminar Fatigue analysis
0 [DGS]
Rotation
direction
-90 [DGS]
90 [DGS]
Z
180 [DGS]
Hot Spot identification by
SE restitutions Y
WT Ref. Axis
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24. Intra-laminar Fatigue analysis
Strain along fibre direction – E11 [MPa]
-0.26 -0.208 -0.156 -0.104 -0.052 0 0.052 0.104 0.156 0.208 0.26
Max.
Max.
Compression
Traction
Extrados
Intrados 0,26831587 UD hot spot
UD hot spot
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25. Intra-laminar Fatigue analysis
Spar Cap hot spots Lamination Layout
PLIES OF TRIAX
Super-Element
Retained nodes
PLIES OF UD Hub
1
connection
Aerodynamic
PLIES OF TRIAX 2 – 16 loads
connection
Hot
PLY OF ADHESIVE
Spot
PLIES OF PM45
Lamination Direction
Super-Element + hot spots
15 16
10 11 12 13 14
1 2 3 4 5 6 7 8 9
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26. Intra-laminar Fatigue analysis
PLIES OF TRIAX
Stiffest Ply
UD 3202001
PLIES OF UD
UD 3202016
Most External Ply
TRIAX 1002001
PLIES OF TRIAX
PLY OF ADHESIVE
TRIAX 4002002
Most Internal Ply PLIES OF PM45
PM45 6002002
Softest Ply
ADHESIVE 5002001
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27. Intra-laminar Fatigue analysis
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28. Intra-laminar Fatigue analysis
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29. Intra-laminar Fatigue analysis
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30. Conclusions
UD MATERIALS COMPARISON
1.COST SAVINGS: Thanks to the higher stiffness and lower density of the Ultrablade®
Fabrics material the Ultra.-Blade is lighter than the Adv.-Blade. In addition, the cost savings
achieved by using the Ultrablade® Fabrics material are higher than 17%.
2.LOADS REDUCTION: Thanks to this weight reduction, the loads on other components are
also reduced
3.BLADE TIP DEFLECTION: Due to the weight optimization performed, the Ultra.-Blade is
softer than the Adv.-Blade, thus also this blade shows the maximum tip deflection. However,
according to the GL and DNV certification guidelines it is still acceptable and no crashes
between the blade and the tower are expected
4.STRENGHT ANALYSIS: The Ultra.-Blade shows higher stress level than the Adv.-Blade.
But due to the fact that the ultimate strength of the Ultrablade® Fabrics material is higher than
those of the Advantex® material, the calculated safety factors for both Blades are similar.
Moreover, according to the GL and DNV certification guidelines, both blades fulfill the
requirements in terms of strength and buckling analyses
5.FATIGUE ANALYSIS: Although the alternating stress level on the Ultra.-Blade are higher
than those calculated on the Adv.-Blade, the hot-spots accumulated damage are similar for
both blades, since the traction and compression static ultimate strength, the fatigue strength
for 1cycle and the SN slope of the Ultrablade® Fabrics material are higher than those of the
Advantex® Material. According to the GL and DNV certification guidelines, a life higher than
20 years is expected for both blades
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31. Conclusions
FATIGUE METHOD
ADVANTADGES
1. Thanks to the fatigue method developed in this work, it is possible to compute directly
from the mechatronic wind turbine model the cycles of intra-laminar stress / strain.
Therefore further time consuming local fatigue analysis based on the linear superposition
of transient signals and unitary loads can be avoided.
2. As the counting of intra-laminar stress / strain cycles is performed directly in the non-
linear mechatronic wind turbine model where all the physical phenomena and
components interact through strong couplings, it is expected that the calculated damage
by using such method are more realistic than those obtained from the local uncoupled
fatigue approaches.
DRAWBACKS:
1. The hot spots have to be identified beforehand
2. Currently the method is limited to a few number of hot spots
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32. Thank you very much
for your attention
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