© ForWind1

Prof. Peter Schaumann, LUHKarsten Schürmann, LUHDr. Andreas Pittner, BAMProf. Michael Rethmeier, BAM

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Experimental investigations on the fatigue resistance of automatically welded tubular X-joints for jacket support structures

EERA DeepWind'202015 - 17 January 2020, Trondheim, Norway

Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Motivation Innovative standardised jacket foundations

© www.alpha-ventus.de

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Motivation Innovative standardised jacket foundations

© www.alpha-ventus.de © www.alpha-ventus.de

© WAZ Foto Pool

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Outline

© s

zmr.d

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Mat

thia

sD

örin

g

Axial Fatigue Tests

z [m

m]

y [mm]

Automatically Welding Procedure

Fatigue TestAnalysis

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Geometrical Dimensions

Scaled tubular X-joint Scaling 1:3.3

S355 J2 + Z 35

β= = 0.6

τ= = 0.44

dBraceDChord

tBraceTChord

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Weld Seam Preparation

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Automatically Welding Procedure

S… Start ofWelding

E… End ofWelding

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Laser Scanning of Weld Geometry

Scanning of weld geometry utilizing a blue line laser Input for numerical analysis

040 2060 -60-40-20

0

20

40

60

80

z [m

m]

y [mm]

Weld SeamGroove

Saddle position (270°)

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

6020 400 120100800

20

40

60

80

z [m

m]

y [mm]

Saddle position (270°)

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Comparing weld geometry of 28 tubular X-joints

Reproducibility of Weld Geometry

Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Reproducibility of Weld Geometry

6020 400 120100800

20

40

60

80

z [m

m]

y [mm]

Saddle position (270°)

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Δmax ≈ 0.8 mm

Δnotch ≈ 0.2 mm

Comparing weld geometry of 28 tubular X-joints Good reproducibility is given

Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Test Setup of Axial Fatigue Tests

High cycle fatigue range;R = 0.1; f = 5 Hz

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Test Setup of Axial Fatigue Tests

High cycle fatigue range;R = 0.1; f = 5 Hz Through thickness crack Loss of over/under pressure

Pres

sure

[bar

] 0

-0.2

Pressure

Loss of pressure

-0.4-0.6-0.8-1.0

Number of Cycles [-]1 2 3 4

x105

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Test Setup of Axial Fatigue Tests

1 mm

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High cycle fatigue range;R = 0.1; f = 5 Hz Through thickness crack Loss of over/under pressure Optical digitization of

damage development

Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Fatigue Damage Digitization

Saddle

SaddleBrace

Weld

Chord y

xεx [%]

0.0 4.0 8.0

Digital image correlation measurement of fatigue damage development 3D surface model of hot spot

for unloaded X-joint Axial fatigue test with ΔσN = 41.3 MPa

N = 0 Cycles

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Fatigue Damage Digitization

Brace

Weld

Chord

Saddle

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

SaddleBrace

Weld

Chord y

xεx [%]

0.0 4.0 8.0

Fatigue Damage Development

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 x106

Number of Cycles [-]

Dis

plac

emen

t[m

m]

0.2

0.4

0.6

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Brace

Weld

Chord y

xεx [%]

0.0 4.0 8.0

First Visible Crack

Saddle

Fatigue Damage Development

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 x106

Number of Cycles [-]

Dis

plac

emen

t[m

m]

0.2

0.4

0.6

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Fatigue Damage Development

Brace

Weld

Chord y

x

εx [%]0.0 4.0 8.0

Saddle

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 x106

Number of Cycles [-]

Dis

plac

emen

t[m

m]

0.2

0.4

0.6

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Fatigue Damage Development

Saddle

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 x106

Number of Cycles [-]

Dis

plac

emen

t[m

m]

0.2

0.4

0.6

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

F

F

S-N Curve acc. to EC3 Background Doc.

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

F

F

Increased S-N curve (FAT 126, m=3) for automatically welded X-joints

S-N Curve acc. to EC3 Background Doc.

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

F

F

S-N Curve acc. to EC3 Background Doc.

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Increased S-N curve (FAT 126, m=3) for automatically welded X-joints

Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

F

F

S-N Curve acc. to EC3 Background Doc.

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Increased S-N curve (FAT 126, m=3) for automatically welded X-joints

Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Summary and Outlook

Fatigue resistance of automatically welded tubular X-joints 32 fatigue tests on single- and double-sided

automatically welded X-joints Increased S-N curve (FAT126) for

the robot welded tubular X-joints Monitoring of damage/crack

development utilizing DIC possible

Improving the automatically welding procedure

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Karsten Schürmann – Experimental investigations on the fatigue resistance of automatically welded tubular X-joints

Thank you for your attention!

Thank you to our project partners and supporters!

www.stahlbau.uni-hannover.de www.forwind.de

The IGF project 19104 N of the FOSTA was supported via AiFwithin the programme for promoting the Industrial Collective Research (IGF) of the German Ministry of Economic Affairs and Energy (BMWi), based on a resolution of the German Parliament.

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