kSIST FprEN IEC 61400-8:2024

Wind energy generation systems - Part 8: Design of wind turbine structural components

IEC 61400-8:2024 outlines the minimum requirements for the design of wind turbine nacelle-based structures and is not intended for use as a complete design specification or instruction manual. This document focuses on the structural integrity of the structural components constituted within and in the vicinity of the nacelle, including the hub, mainframe, main shaft, associated structures of direct-drives, gearbox structures, yaw structural connection, nacelle enclosure. It also addresses connections of the structural components to control and protection mechanisms, as well as structural connections of electrical units and other mechanical systems. This document focuses primarily on ferrous material-based nacelle structures but can apply to other materials also as appropriate

Windenergieanlagen – Teil 8: Design von Windenergieanlagen-Strukturkomponenten

Systèmes de génération d'énergie éolienne - Partie 8: Conception des composants structurels des éoliennes

l'IEC 61400-8:2024 définit les exigences minimales de conception des structures d'éoliennes sur nacelles et n'est pas destinée à servir de spécification de conception complète ou de manuel d'instructions. Le présent document porte sur l'intégrité structurelle des composants structurels constitués à l'intérieur et à proximité de la nacelle, y compris le moyeu, le cadre principal, l'arbre principal, les structures associées d'entraînement direct, les structures des boîtes de vitesse, la connexion structurelle d'orientation, l'enveloppe de la nacelle. Il traite également des connexions des composants structurels aux mécanismes de commande et de protection, ainsi que les connexions structurelles aux unités électriques et aux autres systèmes mécaniques. Le présent document concerne principalement les structures de nacelle en matériaux ferreux, mais peut également s'appliquer à d'autres matériaux, le cas échéant. La conception des assemblages boulonnés et soudés dans les structures de nacelle est incluse, ainsi que les composants coulés et forgés.

Sistemi za proizvodnjo energije na veter - 8. del: Projektiranje delov konstrukcije vetrnih turbin

General Information

• Status: Not Published
• Public Enquiry End Date: 24-Nov-2022
• ICS: 27.180 - Wind turbine energy systems
• Technical Committee: IEHT - Electrotechnics - Hydraulic turbins
• Current Stage: 5020 - Formal vote (FV) (Adopted Project)
• Start Date: 06-Mar-2024
• Due Date: 24-Apr-2024
• Completion Date: 15-Mar-2024
• Ref Project: FprEN IEC 61400-8:2024 - Wind energy generation systems - Part 8: Design of wind turbine structural components

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN IEC 61400-8:2022
01-november-2022
Sistemi za proizvodnjo energije na veter - 8. del: Projektiranje delov konstrukcije
vetrnih turbin
Wind energy generation systems - Part 8: Design of wind turbine structural components
Systèmes de génération d'énergie éolienne - Partie 8: Conception des composants
structurels des éoliennes
Ta slovenski standard je istoveten z: prEN IEC 61400-8:2022
ICS:
27.180 Vetrne elektrarne Wind turbine energy systems
oSIST prEN IEC 61400-8:2022 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN IEC 61400-8:2022
oSIST prEN IEC 61400-8:2022
88/897/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 61400-8 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2022-09-02 2022-11-25
SUPERSEDES DOCUMENTS:
88/797/CD, 88/896/CC
IEC TC 88 : WIND ENERGY GENERATION SYSTEMS
SECRETARIAT: SECRETARY:
Denmark Mrs Christine Weibøl Bertelsen
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:

Other TC/SCs are requested to indicate their interest, if any, in this
CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of CENELEC,
is drawn to the fact that this Committee Draft for Vote (CDV) is
submitted for parallel voting.
The CENELEC members are invited to vote through the CENELEC
online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they are aware
and to provide supporting documentation.

TITLE:
Wind energy generation systems – Part 8: Design of wind turbine structural components

PROPOSED STABILITY DATE: 2026
NOTE FROM TC/SC OFFICERS:
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.

oSIST prEN IEC 61400-8:2022
– 2 – IEC CDV 61400-8  IEC 2022
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Definitions . 10
4 Symbols and abbreviations . 13
5 Reliability Considerations . 15
5.1 Approaches to reliability based design . 15
5.2 Models and Basic Variables for Structural Verification . 16
5.2.1 Material Properties. 17
5.3 Partial Safety Factors and Reliability Targets . 17
6 Application of Loads and Analysis Models . 18
6.1 Loads Models . 18
6.2 Analysis model. 18
6.2.1 Load path modelling . 18
6.2.2 Application of Load components . 18
6.2.3 Boundary Conditions . 19
6.3 Modelling of nonlinear mechanical behaviour . 19
6.3.1 Nonlinear stress effects . 19
6.3.2 Application of Ultimate loads . 19
6.3.3 Application of Fatigue loads . 19
6.4 Partial Safety Factors . 20
6.5 Partial safety factor for resistance . 22
6.6 Nacelle and Hub Component Consideration . 24
6.6.1 Hub structure and bolts. 24
6.6.2 Nacelle front structure (Alternatively : Mechanical drive train structure) . 25
6.6.3 Gearbox structure . 25
6.6.4 Yaw structure . 25
6.6.5 Nacelle rear structure . 26
6.6.6 Nacelle cover and spinner . 26
7 Deflection analysis . 28
8 Strength Verification . 28
8.1 Determination of stress and strain . 28
8.2 Material properties . 28
8.2.1 Influence of size . 29
8.3 Static strength assessment . 29
8.3.1 Cast, forged and steel components . 29
8.3.2 Welded structures . 31
8.3.3 Bolted joints . 31
8.3.4 Fiber reinforced material . 32
8.4 Fatigue strength assessment . 32
8.4.1 Fatigue strength methods . 32

oSIST prEN IEC 61400-8:2022
IEC CDV 61400-8  IEC 2022 – 3 –
8.4.2 Determination of local stresses . 32
8.4.3 Stress hypothesis for fatigue . 32
8.4.4 S/N curves . 32
8.4.5 Influence on fatigue strength . 33
8.4.6 Partial safety factors for fatigue . 34
8.4.7 Damage accumulation . 35
8.4.8 Bolted joints . 36
8.4.9 Fiber reinforced material . 36
8.5 Fracture mechanics assessment . 36
8.5.1 Define objective . 37
8.5.2 Material Parameter . 37
8.5.3 Defect Model . 38
8.5.4 Structural model . 39
8.5.5 Loading . 39
8.5.6 Strength Assessment . 39
8.6 Fracture mechanics-based design . 42
9 Material data for design from testing . 43
9.1 Qualification of Material . 43
9.2 Derivation of static strength and impact energy properties (base material) . 43
9.3 Derivation of fatigue strength properties (base material) . 43
9.4 Welded Joints . 44
9.5 Cast, Forged and steel . 44
9.5.1 Derivation of Static strength properties . 44
9.5.2 Fracture toughness . 44
9.5.3 Derivation of fatigue strength properties . 44
9.6 Bolts . 46
9.7 Nacelle Cover . 46
10 Model verification and validation . 46
Annex A - Model Verification and Validation Methods (informative) . 47
A.1 Verification . 47
A.2 Validation( Laboratory testing) . 47
A.3 Validation (Field experience) . 47
Annex B : Welded Joint Stresses (informative) . 48
Annex C (Informative) . 50
S-N Curve determination by test, statistical evaluation and influencing factors . 50
C.1 General . 50
C.2 S-N Curve . 50
C.3 specimens . 50
C.4 Test Procedure . 50
C.4.1 Finite life line . 51
C.4.2 Long life fatigue regime . 51
C.5 Influencing factors of S-N curve . 51
Annex D : Limit State Equations (Informative) . 52
D.1 Yielding failure . 52
D.2 Fatigue Limit State Equation . 53
D.3 Fatigue Assessment Based on Fracture Mechanics . 56

oSIST prEN IEC 61400-8:2022
– 4 – IEC CDV 61400-8  IEC 2022
Annex E Load Effect Uncertainty Computation (Informative) . 59
Annex F (informative) : Considerations for structural elements. 62
F.1 General . 62
F.2 Global and local failures . 62
F.3 Mean stress influence . 63
Bibliography . 65

oSIST prEN IEC 61400-8:2022
IEC CDV 61400-8  IEC 2022 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WIND ENERGY GENERATION SYSTEMS
Part 8: Design of Wind Turbine Structural Components

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for
standardization comprising all national electrotechnical committees (IEC National
Committees). The object of IEC is to promote international co-operation on all questions
concerning standardization in the electrical and electronic fields. To this end and in addition
to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to
as “IEC
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