Non-proportionality analysis of multi-axial fatigue stress histories in trailing edge adhesive joints of wind turbine rotor blades

<p>The dynamic response of wind turbine rotor blades can result in multi-axial, non-proportional stress histories in the adhesive joints. These are not properly considered in current design guidelines and standards. In this paper, the concept of non-proportionality factors is utilized for the...

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Main Authors: C. Balzani, P. Noever Castelos
Format: Article
Language:English
Published: Copernicus Publications 2025-07-01
Series:Wind Energy Science
Online Access:https://wes.copernicus.org/articles/10/1249/2025/wes-10-1249-2025.pdf
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author C. Balzani
P. Noever Castelos
author_facet C. Balzani
P. Noever Castelos
author_sort C. Balzani
collection DOAJ
description <p>The dynamic response of wind turbine rotor blades can result in multi-axial, non-proportional stress histories in the adhesive joints. These are not properly considered in current design guidelines and standards. In this paper, the concept of non-proportionality factors is utilized for the quantification of the degree of non-proportionality. A novel formulation is proposed and verified, followed by its application to the analysis of trailing edge adhesive joints of three different blade designs with varying blade sizes. Two simple fatigue analysis concepts, one based on global equivalent stresses and the other on the search for a critical plane, are evaluated with respect to their ability to account for multi-axial, non-proportional stress time series.</p> <p>A clear correlation of the degree of non-proportionality with the blade size was not found, as the blade response depends on not only the turbine size but also the blade design philosophy. A remarkable degree of non-proportionality was observed for all three blades. The fatigue damage criteria employed in this study revealed that the critical-plane approach can deal with non-proportional, multi-axial stress time series and therefore is more precise when non-proportionality is involved. The global equivalent stress approach seems to provide conservative predictions. However, there are implications from the literature that global equivalent stress approaches can result in non-conservative estimates under specific circumstances, so further research including validation of appropriate models is necessary for final conclusions.</p>
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spelling doaj-art-e15f8453cd2045b5a688303f371694512025-08-20T02:44:38ZengCopernicus PublicationsWind Energy Science2366-74432366-74512025-07-01101249126710.5194/wes-10-1249-2025Non-proportionality analysis of multi-axial fatigue stress histories in trailing edge adhesive joints of wind turbine rotor bladesC. Balzani0P. Noever Castelos1Institute for Wind Energy Systems, Leibniz University Hannover, Appelstr. 9A, 30167 Hanover, GermanyInstitute for Wind Energy Systems, Leibniz University Hannover, Appelstr. 9A, 30167 Hanover, Germany<p>The dynamic response of wind turbine rotor blades can result in multi-axial, non-proportional stress histories in the adhesive joints. These are not properly considered in current design guidelines and standards. In this paper, the concept of non-proportionality factors is utilized for the quantification of the degree of non-proportionality. A novel formulation is proposed and verified, followed by its application to the analysis of trailing edge adhesive joints of three different blade designs with varying blade sizes. Two simple fatigue analysis concepts, one based on global equivalent stresses and the other on the search for a critical plane, are evaluated with respect to their ability to account for multi-axial, non-proportional stress time series.</p> <p>A clear correlation of the degree of non-proportionality with the blade size was not found, as the blade response depends on not only the turbine size but also the blade design philosophy. A remarkable degree of non-proportionality was observed for all three blades. The fatigue damage criteria employed in this study revealed that the critical-plane approach can deal with non-proportional, multi-axial stress time series and therefore is more precise when non-proportionality is involved. The global equivalent stress approach seems to provide conservative predictions. However, there are implications from the literature that global equivalent stress approaches can result in non-conservative estimates under specific circumstances, so further research including validation of appropriate models is necessary for final conclusions.</p>https://wes.copernicus.org/articles/10/1249/2025/wes-10-1249-2025.pdf
spellingShingle C. Balzani
P. Noever Castelos
Non-proportionality analysis of multi-axial fatigue stress histories in trailing edge adhesive joints of wind turbine rotor blades
Wind Energy Science
title Non-proportionality analysis of multi-axial fatigue stress histories in trailing edge adhesive joints of wind turbine rotor blades
title_full Non-proportionality analysis of multi-axial fatigue stress histories in trailing edge adhesive joints of wind turbine rotor blades
title_fullStr Non-proportionality analysis of multi-axial fatigue stress histories in trailing edge adhesive joints of wind turbine rotor blades
title_full_unstemmed Non-proportionality analysis of multi-axial fatigue stress histories in trailing edge adhesive joints of wind turbine rotor blades
title_short Non-proportionality analysis of multi-axial fatigue stress histories in trailing edge adhesive joints of wind turbine rotor blades
title_sort non proportionality analysis of multi axial fatigue stress histories in trailing edge adhesive joints of wind turbine rotor blades
url https://wes.copernicus.org/articles/10/1249/2025/wes-10-1249-2025.pdf
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AT pnoevercastelos nonproportionalityanalysisofmultiaxialfatiguestresshistoriesintrailingedgeadhesivejointsofwindturbinerotorblades