Reducing the number of load cases for fatigue damage assessment of offshore wind turbine support structures using a simple severity-based sampling method

Stieng, Lars Einar S.; Muskulus, Michael

doi:10.5194/wes-3-805-2018

Cited by 11 publications

(2 citation statements)

References 13 publications

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“…Moreover, it was discovered that the introduced uncertainty grows at a lower rate than the dimension reduction of the set. Reference [170] showed that a small set of the most severe fatigue design load cases for a particular turbine suffice for an accurate prediction of the fatigue damage of a slightly different design, for instance for a related or optimized design.…”

Section: Load Cases Reductionmentioning

confidence: 99%

Decoupled Modelling Approaches for Environmental Interactions with Monopile-Based Offshore Wind Support Structures

2020

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To meet the political goals regarding renewable energy production, offshore wind keeps expanding to waters with larger depths and harsher conditions, while the turbine size continues to grow and ever-larger foundation structures are required. This development can only be successful if further cuts in the levelized cost of energy are established. Regarding the design of the foundation structures, a particular challenge in this respect relates to the reduction of the total computational time required for the design. For both practical and commercial reasons, the decoupled modelling of offshore wind support structures finds a common application, especially during the preliminary design stage. This modelling approach aims at capturing the relevant characteristics of the different environment-structure interactions, while reducing the complexity as much as possible. This paper presents a comprehensive review of the state-of-the-art modelling approaches of environmental interactions with offshore wind support structures. In this respect, the primary focus is on the monopile foundation, as this concept is expected to remain the prominent solution in the years to come. Current challenges in the field are identified, considering as well the engineering practice and the insights obtained from code comparison studies and experimental validations. It is concluded that the decoupled analysis provides valuable modelling perspectives, in particular for the preliminary design stage. In the further development of the different modelling strategies, however, the trade-off with computational costs should always be kept in mind.

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Section: Load Cases Reductionmentioning

confidence: 99%

Decoupled Modelling Approaches for Environmental Interactions with Monopile-Based Offshore Wind Support Structures

2020

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“…First, there are those approaches that still consider a deterministic grid, but only use the most important grid points. Stieng and Muskulus [15,16] determine the most important grid points in a computationally expansive preliminary study using a full grid. Velarde and Bachynski [17] estimate the relevant grid points by applying a simple sea state-damage correlation.…”

Section: Introductionmentioning

confidence: 99%

Validation of Improved Sampling Concepts for Offshore Wind Turbine Fatigue Design

et al. 2019

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Fatigue damage is a design-driving phenomenon for substructures of offshore wind turbines. However, fatigue design based on numerical simulations is quite uncertain. One main reason for this uncertainty is scattering offshore conditions combined with a limited number of simulations (samples). According to current standards, environmental conditions are sampled using a deterministic grid of the most important environmental conditions (e.g., wind speed and direction, significant wave height, and wave period). Recently, there has been some effort to reduce the inherent uncertainty of damage calculations due to limited data by applying other sampling concepts. Still, the investigation of this uncertainty and of methods to reduce it is a subject of ongoing research. In this work, two improved sampling concepts—previously proposed by the authors and reducing the uncertainty due to limited sampling—are validated. The use of strain measurement data enables a realistic estimate of the inherent uncertainty due to limited samples, as numerical effects, etc., are excluded. Furthermore, an extensive data set of three years of data of two turbines of the Belgian wind farm Northwind is available. It is demonstrated that two previously developed sampling methods are generally valid. For a broad range of model types (i.e., input dimensions as well as degrees of non-linearity), they outperform standard sampling concepts such as deterministic grid sampling or Monte Carlo sampling. Hence, they can reduce the uncertainty while keeping the sampling effort constant, or vice versa.

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State‐of‐the‐Art Framework for Structural Design of Offshore Wind Jacket Foundations

et al. 2019

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A state-of-the-art framework for design of jacket foundations for offshore wind turbines is presented. It is illustrated how an efficient, yet highly accurate structural model can be achieved by a combination of a comprehensive beam finite element model and more detailed shell/solid finite element models, where the former suffices for representing the overall global behaviour, while the latter improve the representation of non-trivial structural details such as the transition piece and tubular joints. Hereby the verification of the majority of the structural elements according to various design codes can be automated on beam element level, while the fatigue performance via the hot-spot method as well as detailed stress and buckling analysis for relevant joints and details can be performed based on the detailed shell/solid finite element models readily available for stiffness representation. This computational framework ensures consistency between the local and global description levels and an efficient cloud interface facilitates the thousands of design load cases that typically requires consideration for a full detailed design to be simulated within a reasonable amount of time.

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Reducing the number of load cases for fatigue damage assessment of offshore wind turbine support structures using a simple severity-based sampling method

Cited by 11 publications

References 13 publications

Decoupled Modelling Approaches for Environmental Interactions with Monopile-Based Offshore Wind Support Structures

Decoupled Modelling Approaches for Environmental Interactions with Monopile-Based Offshore Wind Support Structures

Validation of Improved Sampling Concepts for Offshore Wind Turbine Fatigue Design

State‐of‐the‐Art Framework for Structural Design of Offshore Wind Jacket Foundations

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