Articles | Volume 7, issue 5
https://doi.org/10.5194/wes-7-1919-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wes-7-1919-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
26 Sep 2022
Research article |
| 26 Sep 2022
| 26 Sep 2022
Probabilistic temporal extrapolation of fatigue damage of offshore wind turbine substructures based on strain measurements
Clemens Hübler
CORRESPONDING AUTHOR
Institute of Structural Analysis, Leibniz University Hannover/ForWind, Appelstr. 9a, 30167 Hanover, Germany
Raimund Rolfes
Institute of Structural Analysis, Leibniz University Hannover/ForWind, Appelstr. 9a, 30167 Hanover, Germany
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For the design of offshore wind turbines, the knowledge of environmental conditions is important. However, real high-quality data are rare. This is why a comprehensive database of environmental conditions at wind turbine locations in the North and Baltic Sea is derived using real data. The main purpose of this work is to collect realistic data for probabilistic approaches. Hence, all results are freely available.
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In this work, for the first time, a Kriging meta-model is detailed analysed to replace the simulation model of an idling offshore wind turbine. It becomes clear that the findings regarding meta-modelling of the idling wind turbine are generally similar to the findings regarding meta-modelling of the same wind turbine in operation. Only for the approximation of the rotor blade root bending moments, two additional input parameters have to be included compared to the same wind turbine in operation.
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This study investigates dynamic displacement estimation using double-time-integrated acceleration signals for future application in load monitoring based on accelerometers. To estimate displacements without amplitude distortion, a tilt error compensation method for low-frequency vibrations of tower structures using the static bending line without the need for additional sensors is presented. The method is validated using a full-scale onshore wind turbine tower and a terrestrial laser scanner.
Susanne Könecke, Jasmin Hörmeyer, Tobias Bohne, and Raimund Rolfes
Wind Energ. Sci., 8, 639–659, https://doi.org/10.5194/wes-8-639-2023, https://doi.org/10.5194/wes-8-639-2023, 2023
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Extensive measurements in the area of wind turbines were performed in order to validate a sound propagation model. The measurements were carried out under various environmental conditions and included the acquisition of acoustical, meteorological and wind turbine performance data. By processing and analysing the measurement data, validation cases and input parameters for the propagation model were derived. Comparing measured and modelled propagation losses, generally good agreement is observed.
Clemens Jonscher, Benedikt Hofmeister, Tanja Grießmann, and Raimund Rolfes
Wind Energ. Sci., 7, 1053–1067, https://doi.org/10.5194/wes-7-1053-2022, https://doi.org/10.5194/wes-7-1053-2022, 2022
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This work presents a method to use low-noise IEPE sensors in the low-frequency range down to 0.05 Hz. In order to achieve phase and amplitude accuracy with this type of sensor in the low-frequency range, a new calibration procedure for this frequency range was developed. The calibration enables the use of the low-noise IEPE sensors for large structures, such as wind turbines. The calibrated sensors can be used for wind turbine monitoring, such as fatigue monitoring.
Jan Häfele, Cristian G. Gebhardt, and Raimund Rolfes
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To reduce the levelized costs of offshore wind energy, capital expenses of substructures have to be decreased significantly. Therefore, structural optimization approaches have been proposed in the recent past, mainly to improve the design of jackets. This work proposes a holistic approach to jacket optimization, which addresses some problems arising from methods that were presented in the literature.
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The present work provides a technical basis for the design of jacket structures used as substructures for offshore wind turbines. This involves models for the geometry, costs, and structural design code checks. An example application is shown in this paper, in which three different structural designs are compared. This work may lead to improved design approaches and finally to a cost reduction of offshore substructures.
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For the design of offshore wind turbines, the knowledge of environmental conditions is important. However, real high-quality data are rare. This is why a comprehensive database of environmental conditions at wind turbine locations in the North and Baltic Sea is derived using real data. The main purpose of this work is to collect realistic data for probabilistic approaches. Hence, all results are freely available.
Related subject area
Thematic area: Materials and operation | Topic: Fatigue
Load case selection for finite-element simulations of wind turbine pitch bearings and hubs
Data-driven surrogate model for wind turbine damage equivalent load
Probabilistic surrogate modeling of damage equivalent loads on onshore and offshore wind turbines using mixture density networks
Effect of scour on the fatigue life of offshore wind turbines and its prevention through passive structural control
Review of rolling contact fatigue life calculation for oscillating bearings and application-dependent recommendations for use
Non-proportionality analysis of multiaxial fatigue stress histories in trailing edge adhesive joints of wind turbine rotor blades
Quantifying the effect of low-frequency fatigue dynamics on offshore wind turbine foundations: a comparative study
Sensitivity analysis of the effect of wind and wake characteristics on wind turbine loads in a small wind farm
Damage equivalent load synthesis and stochastic extrapolation for fatigue life validation
Matthias Stammler and Florian Schleich
Wind Energ. Sci., 10, 813–826, https://doi.org/10.5194/wes-10-813-2025, https://doi.org/10.5194/wes-10-813-2025, 2025
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The structures at the center of wind turbine rotors are loaded by three rotor blades. The rotor blades have different loads, which depend on their positions and the incoming wind. The number of possible different loads is too high to simulate each of them for later design of the structures. This work attempts to reduce the number of necessary simulations by exploring inherent relations between the loads of the three rotor blades.
Rad Haghi and Curran Crawford
Wind Energ. Sci., 9, 2039–2062, https://doi.org/10.5194/wes-9-2039-2024, https://doi.org/10.5194/wes-9-2039-2024, 2024
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This journal paper focuses on developing surrogate models for predicting the damage equivalent load (DEL) on wind turbines without needing extensive aeroelastic simulations. The study emphasizes the development of a sequential machine learning architecture for this purpose. The study also explores implementing simplified wake models and transfer learning to enhance the models' prediction capabilities in various wind conditions.
Deepali Singh, Richard Dwight, and Axelle Viré
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The selection of a suitable site for the installation of a wind turbine plays an important role in ensuring a safe operating lifetime of the structure. In this study, we show that mixture density networks can accelerate this process by inferring functions from data that can accurately map the environmental conditions to the loads but also propagate the uncertainty from the inflow to the response.
Yu Cao, Ningyu Wu, Jigang Yang, Chao Chen, Ronghua Zhu, and Xugang Hua
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This study investigates the offshore wind turbine support structure’s fatigue life by a rapid numerical model which considers the effects of scour and a tuned mass damper. An optimization technique is proposed to find the damper's optimal parameters, considering time-varying scour. It is found that the damper optimized by the proposed optimization technique performs better than an initially designed damper in terms of fatigue life enhancement.
Oliver Menck and Matthias Stammler
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Oscillating bearings, like rotating bearings, can fail due to rolling contact fatigue. But the publications in the literature on this topic are difficult to understand. In order to help people decide which method to use, we have summarized the available literature. We also point out some errors and things to look out for to help engineers that want to calculate the rolling contact fatigue life of an oscillating bearing.
Claudio Balzani and Pablo Noever Castelos
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Wind turbine rotor blades consist of several subcomponents that are glued together. Such connections are subjected to fatigue loads. This paper analyzes the characteristics of those fatigue loads in trailing edge adhesive joints of three different wind turbine rotor blades. It is shown that the fatigue loads have significant degrees of non-proportionality, which helps engineers to choose a valid fatigue analysis framework and to design more reliable and cost-efficient rotor blades in the future.
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Analysis of long-term fatigue damage of four offshore wind turbines using 3 years of measurement data was performed for the first time to gain insight into the low-frequency fatigue damage (LFFD) impact on overall consumed life. The LFFD factor depends on the (linear) stress–life (SN) curve slope, heading, site, signal, and turbine type. Up to ∼ 65 % of the total damage can be related to LFFDs. Therefore, in this case study, the LFFD effect has a significant impact on the final damage.
Kelsey Shaler, Amy N. Robertson, and Jason Jonkman
Wind Energ. Sci., 8, 25–40, https://doi.org/10.5194/wes-8-25-2023, https://doi.org/10.5194/wes-8-25-2023, 2023
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This work evaluates which wind-inflow- and wake-related parameters have the greatest influence on fatigue and ultimate loads for turbines in a small wind farm. Twenty-eight parameters were screened using an elementary effects approach to identify the parameters that lead to the largest variation in these loads of each turbine. The findings show the increased importance of non-streamwise wind components and wake parameters in fatigue and ultimate load sensitivity of downstream turbines.
Anand Natarajan
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The article delineates a novel procedure to use 10 min measurement statistics with few known parameters of the wind turbine to determine the long-term fatigue damage probability and compare this with the expected damage levels from the design to provide an indicator of structural reliability and remaining life. The results are validated with load measurements from a wind turbine within an offshore wind farm.
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Short summary
Offshore wind turbines are beginning to reach their design lifetimes. Hence, lifetime extensions are becoming relevant. To make well-founded decisions on possible lifetime extensions, fatigue damage predictions are required. Measurement-based assessments instead of simulation-based analyses have rarely been conducted so far, since data are limited. Therefore, this work focuses on the temporal extrapolation of measurement data. It is shown that fatigue damage can be extrapolated accurately.
Offshore wind turbines are beginning to reach their design lifetimes. Hence, lifetime extensions...
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