ib nafems samtech blade optimization & advanced fatigue analysis

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

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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


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Thickness distribution

Blade Length [m]

Th

ickn

ess [m

]

Z

X

Wind


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Twist distribution

Blade Length [m]

Tw

ist a

ng

le [º

]

Y

X

Wind


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Pre-bend

distribution

Blade Length [m]

Dis

tan

ce

with

re

sp

ect to

pitch

axis

[m

]

Z

X

Wind


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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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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


LB1 LA1

LA3 LB3

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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


FOAM (max. thickness = 15mm)

2 PLIES OF TRIAX

1 PLY OF ADHESIVE

2 PLIES OF PM45

2 PLIES OF TRIAX

Span length


LB1 LA1

LA3 LB3

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FEM creation and optimization ULTRA.-BLADE

Spar-Cap stacking laws

ULTRA.-BLADE

Trailing-Edge stacking laws

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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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Blade integration

Number of elements Type : 72 41HINGE

ElementsNumber of elements Type : 10 15

Number of elements Type : 74 1DIST


BPR BEAM

Elements

Number of elements Type : 75 81BUSHING


AERO

Elements

Number of elements Type : 78 25 Rigid Bodies Number of elements Type : 71 132MCE BEAM

Elements

Number of elements Type : 108 9DAMPER


FNLI

Elements

Number of elements Type : 113 15GEAR


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


Number of elements Type : 74 1DIST


BPR BEAM

Elements

Number of elements Type : 75 81BUSHING


AERO

Elements

Number of elements Type : 78 25 Rigid Bodies Number of elements Type : 71 132MCE BEAM

Elements

Number of elements Type : 108 9DAMPER


FNLI

Elements

Number of elements Type : 113 15GEAR


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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Blade integration

Gravity

Samcef for Wind Turbines (S4WT)

mechatronic model

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Blade integration

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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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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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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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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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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


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


PLIES OF TRIAX

PLIES OF UD

PLIES OF TRIAX

PLY OF ADHESIVE

PLIES OF PM45

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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

ib nafems samtech blade optimization & advanced fatigue analysis

Documents

number of ud plies

orgnumber of elements

freedomnumber of elements

blade ultra

blade stressdistribution

blade integration4

mmn plies of ud npmax

plies of triaxa1c1b1