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292 M. Seidel and J. Gößwein 2. Seidel, M.; v. Mutius, M.; Steudel, D.: Design and load calculations for Offshore foundations of a 5 MW turbine. Conference Proceedings DEWEK 2004. Wilhelmshaven: DEWI 2004 3. Seidel, M.; v. Mutius, M.; Rix, P.; Steudel, D.: Integrated analysis of wind and wave loading for complex support structures of Offshore <strong>Wind</strong> Turbines. Conference Proceedings Offshore <strong>Wind</strong> 2005: Copenhagen 2005
54 Benefits of Fatigue Assessment with Local Concepts P. Schaumann and F. Wilke 54.1 Introduction Support structures of offshore wind energy converters for medium to high water depths are supposedly carried out as braced or lattice constructions. Due to the combined dynamic loads from wind and waves the fatigue design is of special interest. The large variety in type and dimensions of tubular joints requires a fatigue design with local approaches. 54.2 Applied Local Concepts The authors gave an overview of expected types of support structures in [1]. State-of-the-art in current offshore standards is the structural stress approach. More sophisticated concepts like the notch stress approach and notch strain approach [2], here referred to as “local approaches”, require detailed FE modelling of the mesoscale weld shape. The applied notch stress approach is based on the recommendations in [3], but with a modified slope of the S–N curve with m = 5 for ND > 5 × 10 6 and without a cut-off limit. This modification fits well to the results of [4] in the high-cycle fatigue range. A fictitious weld toe fillet with a radius ρf=1 mm is applied to the FE model to account for microstructural support. The notch strain approach uses stabilized cyclic material data according to the uniform material law (UML). For the material in the heat-affected zone (HAZ) an increased hardness is considered. To include the mean stress effects, the damage parameter given by PSWT = � (σa + σm)ɛaE (54.1) has been used. Together with the equations by Manson, Coffin and Morrow this leads to a relevant P –N curve. As the shear strains are low for the
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Wind Energy Proceedings of the Euro
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Prof. Dr. Joachim Peinke Dr. Stepha
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VI Preface been presented, spanning
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VIII Contents 3.3 Stochastic Wind F
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X Contents 12.6 Subgrid Scale Turbu
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XII Contents 22 Stochastic Small-Sc
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XIV Contents 32 Handling Systems Dr
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XVI Contents 41 3D Numerical Simula
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XVIII Contents 51 Comparing WAsP an
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XX Contents 58.3 Ultra-High Perform
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XXII List of Contributors Lars Berg
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XXIV List of Contributors Renata Gn
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XXVI List of Contributors A. Kiss D
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XXVIII List of Contributors El˙zbi
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XXX List of Contributors Ivo Sláde
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1 Offshore Wind Power Meteorology B
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1 Offshore Wind Power Meteorology 3
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1 Offshore Wind Power Meteorology 5
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2 Wave Loads on Wind-Power Plants i
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Trubaduren 2 Wave Loads on Wind-Pow
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Base moment (10 6 Nm) 0.4 0.2 −0.
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2 Wave Loads on Wind-Power Plants i
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3 Time Domain Comparison of Simulat
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3 Time Domain Comparison Using Cons
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7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 3 T
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4 Mean Wind and Turbulence in the A
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5 Wind Speed Profiles above the Nor
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5 Wind Speed Profiles above the Nor
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Height [m] 100 90 80 70 60 50 40 30
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6 Fundamental Aspects of Fluid Flow
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f Suu(f, z) / σ 2 u(z) 10 0 10 −
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a) c) −0,375 6 Fluid Flow over Co
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7 Models for Computer Simulation of
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y/h 2.5 2 1.5 1 0.5 0 7 Models for
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8 Power Performance via Nacelle Ane
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9 Pollutant Dispersion in Flow Arou
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x1/B 0.3 0.5 0.8 1.0 9 Pollutant Di
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9 Pollutant Dispersion in Flow Arou
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10 On the Atmospheric Flow Modellin
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11 Comparison of Logarithmic Wind P
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Height above ground in m 100 90 80
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12 Turbulence Modelling and Numeric
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13 Gusts in Intermittent Wind Turbu
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Durations (s) 25 20 15 10 5 13 Gust
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14 Report on the Research Project O
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height z (m) 100 80 60 40 20 0 14 R
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14.6 Outlook 14 Report on the Resea
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15 Simulation of Turbulence, Gusts
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S(ƒ)(m/s) 2 /Hz 15 Simulation of T
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15 Simulation of Turbulence, Gusts
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16 Short Time Prediction of Wind Sp
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ms prediction error [m/s] 16 Short
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16 Short Time Prediction of Wind Sp
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17 Wind Extremes and Scales: Multif
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Log10 E(k)*k**(5/3) 6 4 2 0 5/3 cor
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17.3 Discussion and Conclusion 17 W
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18 Boundary-Layer Influence on Extr
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z/H (a) (b) 4 2 18 Boundary-Layer I
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18.6 Concluding Remarks 18 Boundary
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19 The Statistical Distribution of
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19 The Statistical Distribution of
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20 Superposition Model for Atmosphe
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h(u) 0.5 0.3 0.1 20 Superposition M
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21 Extreme Events Under Low-Frequen
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21 Extreme Events Under Low-Frequen
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22 Stochastic Small-Scale Modelling
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p(σ⏐u) 1 0.8 0.6 0.4 0.2 22 Stoc
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22 Stochastic Small-Scale Modelling
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23 Quantitative Estimation of Drift
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24 Scaling Turbulent Atmospheric St
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24 Scaling Turbulent Atmospheric St
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25 Wind Farm Power Fluctuations P.
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25 Wind Farm Power Fluctuations 141
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d rc q rc V 0 q V 25 Wind Farm Powe
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References 25 Wind Farm Power Fluct
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26 Network Perspective of Wind-Powe
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27 Phenomenological Response Theory
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28 Turbulence Correction for Power
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28 Turbulence Correction for Power
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29 Online Modeling of Wind Farm Pow
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29 Online Modeling of Wind Farm Pow
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30 Uncertainty of Wind Energy Estim
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31 Characterisation of the Power Cu
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32 Handling Systems Driven by Diffe
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32 Handling Systems Driven by Diffe
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33 Experimental Researches of Chara
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33 Experimental Researches of Chara
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34 Methodical Failure Detection in
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34 Methodical Failure Detection in
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35 Modelling of the Transition Loca
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35 Modelling an Airfoil with Surfac
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(Cl/Cd)max 120 110 100 90 80 70 60
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35 Modelling an Airfoil with Surfac
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36 Helicopter Aerodynamics with Emp
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37 Determination of Angle of Attack
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37 Determination of Angle of Attack
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Drag coefficient 0.5 0.4 0.3 0.2 0.
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38 Unsteady Characteristics of Flow
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PSD PSD 38 Unsteady Characteristics
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39 Aerodynamic Multi-Criteria Shape
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39 Multi-Criteria Shape Optimizatio
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39 Multi-Criteria Shape Optimizatio
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40 Rotation and Turbulence Effects
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Cp Xsep/c 1 0.6 0.2 −0.2 −0.6
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Standard deviation of Cp 0.7 0.6 0.
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41 3D Numerical Simulation and Eval
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41 3D-CFD-Simulation of a Wind Turb
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42 Performance of the Risø-B1 Airf
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42 Performance of the Risø-B1 Airf
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43 Aerodynamic Behaviour of a New T
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Page 271 and 272: 44 Numerical Simulation of Dynamic
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Page 275 and 276: 45 Modeling of the Far Wake behind
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Page 279 and 280: 46 Stability of the Tip Vortices in
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Page 283 and 284: 47 Modelling Turbulence Intensities
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Page 293 and 294: References 48 Numerical Computation
Page 295 and 296: 49 Modelling Wind Turbine Wakes wit
Page 297 and 298: U mean / U ref 1 0.9 0.8 0.7 49 Mod
Page 299 and 300: 49.5 Conclusion 49 Modelling Wind T
Page 301 and 302: 50 Prediction of Wind Turbine Noise
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Page 305 and 306: 51 Comparing WAsP and Fluent for Hi
Page 307 and 308: Table 51.1. Measurements and simula
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Page 311 and 312: 52 Fatigue Assessment of Truss Join
Page 317 and 318: 53 Advances in Offshore Wind Techno
Page 319 and 320: Simulation Measurement pitch angle
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Page 325 and 326: ∆σN [N/mm²] 100 10 54 Benefits
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Page 329 and 330: Transverse residual stresses [N/mm
Page 331 and 332: 56 Damage Detection on Structures o
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Page 335 and 336: 57 Influence of the Type and Size o
Page 337 and 338: [W/m 2 ] q t [W/m 5000 4000 3000 20
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Page 343 and 344: 59 A Modular Concept for Integrated
Page 349 and 350: 60 Solutions of Details Regarding F
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Page 353 and 354: 60 Solutions of Details Regarding F
Page 355 and 356: 61 On the Influence of Low-Level Je
Page 357 and 358: Relative Power and Loading [%] 61 O
Page 359 and 360: 62 Reliability of Wind Turbines Exp
Page 361 and 362: 62 Reliability of Wind Turbines 331
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