ib nafems samtech blade optimization & advanced fatigue analysis
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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
www.nafems.org
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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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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2D Aerodynamic Airfoils
Aerodynamic Geometry
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Chord length
distribution
Blade Length [m]
Ch
ord
Le
ng
th [m
]
Z
Y
Aerodynamic Geometry
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Thickness distribution
Blade Length [m]
Th
ickn
ess [m
]
Z
X
Wind
Aerodynamic Geometry
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Twist distribution
Blade Length [m]
Tw
ist a
ng
le [º
]
Y
X
Wind
Aerodynamic Geometry
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Pre-bend
distribution
Blade Length [m]
Dis
tan
ce
with
re
sp
ect to
pitch
axis
[m
]
Z
X
Wind
Aerodynamic Geometry
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FEM creation and optimization
Triax 1 Triax 2 UD PM45 FOAM Adhesive
E1 – E2
A1, A2, from
1m to max.
chord
B1, B2, from
1m to max.
chord
A1, A2, from
max. chord to
39.5 m
B1, B2, from
max. chord
to 39.5 m
C1,C2,
D1,D2 from
max. chord
to 39.5 m
F
C1,C2, D1,D2
from 1m to
max. chord
G
D2
D1
C1
C2
A1
A2
B2
B1
G
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FEM creation and optimization
D2
D1
C1
C2
A1
A2
B2
B1
G
sta
ckin
g la
ws s
ho
win
g v
aria
tio
ns o
f #
2 a
nd
#3
la
min
ate
s.
FROM 60 TO 1 PLY OF TRIAX
n Plies of UD (NPMAX_1 parameter)
FOAM (max. thickness = 15mm)
2 PLIES OF TRIAX
1 PLY OF ADHESIVE
2 PLIES OF PM45
2 PLIES OF TRIAX
Span length
n Plies of UD (NPMAX_3 parameter)
LB1 LA1
LA3 LB3
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FEM creation and optimization
Automatic Optimization in BOSS QUATTRO
Objective = Mass Reduction
Constraints = 1st Flap & 1st Edge frequencies
have to remain the same as for the baseline
Parameters:
LA1: length where number of sparcap UD plies
(zones A1-A2) increases from 0 to max.
LB1: length where number of sparcap UD plies
(zones A1-A2) decreases from max. to 0.
NPMAX_1: max. number of sparcap UD plies
(zones A1-A2)
LA3: length where number of trailing-edge UD
plies (zones B1-B2) increase from 0 to max.
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)
sta
ckin
g la
ws s
ho
win
g v
aria
tio
ns o
f #
2 a
nd
#3
la
min
ate
s.
FROM 60 TO 1 PLY OF TRIAX
n Plies of UD (NPMAX_1 parameter)
FOAM (max. thickness = 15mm)
2 PLIES OF TRIAX
1 PLY OF ADHESIVE
2 PLIES OF PM45
2 PLIES OF TRIAX
Span length
n Plies of UD (NPMAX_3 parameter)
LB1 LA1
LA3 LB3
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FEM creation and optimization
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FEM creation and optimization ULTRA.-BLADE
Spar-Cap stacking laws
ULTRA.-BLADE
Trailing-Edge stacking laws
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FEM creation and optimization
ULTRA.-BLADE: Objective and constraints variation during iterations
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WT Mechatronic model &
Blade integration
Gravity
Aerodynamic loads
Using BEM Theory
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WT Mechatronic model &
Blade integration
Number of elements Type : 72 41HINGE
ElementsNumber of elements Type : 10 15
Number of elements Type : 74 1DIST
ElementsNumber of elements Type : 22 6
BPR BEAM
Elements
Number of elements Type : 75 81BUSHING
ElementsNumber of elements Type : 50 46
AERO
Elements
Number of elements Type : 78 25 Rigid Bodies Number of elements Type : 71 132MCE BEAM
Elements
Number of elements Type : 108 9DAMPER
ElementsNumber of elements Type : 125 1
FNLI
Elements
Number of elements Type : 113 15GEAR
ElementsNumber of elements Type : 159 4
MASS
Elemetns
Number of Elements 376
605
GE25 GEN1 High Fidelity Model ELEMENT DESCRIPTION
Number of Degrees of Freedom 2484
SUPER Elements
Number of Nodes
Number of elements Type : 72 41HINGE
ElementsNumber of elements Type : 10 15
Number of elements Type : 74 1DIST
ElementsNumber of elements Type : 22 6
BPR BEAM
Elements
Number of elements Type : 75 81BUSHING
ElementsNumber of elements Type : 50 46
AERO
Elements
Number of elements Type : 78 25 Rigid Bodies Number of elements Type : 71 132MCE BEAM
Elements
Number of elements Type : 108 9DAMPER
ElementsNumber of elements Type : 125 1
FNLI
Elements
Number of elements Type : 113 15GEAR
ElementsNumber of elements Type : 159 4
MASS
Elemetns
Number of Elements 376
605
GE25 GEN1 High Fidelity Model ELEMENT DESCRIPTION
Number of Degrees of Freedom 2484
SUPER Elements
Number of Nodes
MBS
FEM
Control
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WT Mechatronic model &
Blade integration
Gravity
Samcef for Wind Turbines (S4WT)
mechatronic model
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WT Mechatronic model &
Blade integration
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WT Mechatronic model &
Blade integration
Slave & master nodes are linked through
«weighted constraint equation»:
Φ=∑ αi (Umaster_i - Uslave) =0
1 Slave node
n Master nodes
The individual «constraint factors»:
αi (Umaster_i - Uslave)
correspond ideally to the «real» pressure
distribution of the outer blade skin
αi (Umaster_i - Uslave)
The resulting blade stress
distribution is strongly depended
on the choice of the weights αi
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WT Mechatronic model &
Blade integration Reverse engineering AEROMAPPING procedure
3 1.7 0.4 -0.9 -2.2 -3.5 -4.8 -6.1 -7.4 -8.7 -10 Pressure [KPa]
EXTRADOS
INTRADOS
AEROMAPPING: Blade pressure field
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WT Mechatronic model &
Blade integration
TSAI-WU DISTRIBUTION
Aeromapping
TSAI-WU DISTRIBUTION
15 discrete aerodynamic
Differences lower than 10%
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Intra-laminar Fatigue analysis
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Intra-laminar Fatigue analysis
0 [
DG
S]
180
[D
GS
]
Z
Y WT Ref. Axis
Rotation
direction
Hot Spot identification by SE restitutions
-90 [DGS]
90 [DGS]
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Intra-laminar Fatigue analysis
Intrados
UD hot spot
Max.
Traction
0,26831587
Extrados
UD hot spot
Max.
Compression
-0.26 -0.208 0.26 -0.156 -0.104 -0.052 0 0.052 0.104 0.156 0.208
Strain along fibre direction – E11 [MPa]
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PLIES OF TRIAX
PLIES OF UD
PLIES OF TRIAX
PLY OF ADHESIVE
PLIES OF PM45
Intra-laminar Fatigue analysis
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Super-Element + hot spots
Lamination Direction
Hot
Spot
Spar Cap hot spots Lamination Layout
Super-Element
Retained nodes
1 Hub
connection
2 – 16
Aerodynamic
loads
connection
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Softest Ply
ADHESIVE 5002001
Most Internal Ply
PM45 6002002
TRIAX 4002002
Most External Ply
TRIAX 1002001
UD 3202016
Stiffest Ply
UD 3202001
Intra-laminar Fatigue analysis
PLIES OF TRIAX
PLIES OF UD
PLIES OF TRIAX
PLY OF ADHESIVE
PLIES OF PM45
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Intra-laminar Fatigue analysis
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Intra-laminar Fatigue analysis
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Intra-laminar Fatigue analysis
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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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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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Thank you very much
for your attention
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