BS EN IEC 61400-8:2024
$215.11
Wind energy generation systems – Design of wind turbine structural components
| Published By | Publication Date | Number of Pages |
| BSI | 2024 | 72 |
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
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | undefined |
| 5 | Annex ZA (normative)Normative references to international publicationswith their corresponding European publications |
| 8 | English CONTENTS |
| 11 | FOREWORD |
| 13 | INTRODUCTION |
| 14 | 1 Scope 2 Normative references |
| 16 | 3 Terms, definitions, symbols and abbreviated terms 3.1 Terms and definitions |
| 18 | 3.2 Symbols and abbreviated terms |
| 20 | 4 Reliability considerations 4.1 Approaches to reliability based design |
| 22 | 4.2 Models and basic variables for structural verification 4.2.1 Reliability assessment 4.2.2 Material properties 4.3 Partial safety factors and reliability targets |
| 23 | 5 Application of loads and analysis models 5.1 Loads models 5.2 Analysis model 5.2.1 General 5.2.2 Load path modelling 5.2.3 Application of load components Tables Table 1 – Component classes as in IEC 61400-1:2019 |
| 24 | 5.2.4 Boundary conditions 5.3 Modelling of nonlinear mechanical behaviour 5.3.1 General 5.3.2 Nonlinear stress effects 5.3.3 Application of ultimate loads 5.3.4 Application of fatigue loads |
| 25 | 5.4 Partial safety factors |
| 26 | Table 2 – List of potential sources for modelling deviations Table 3 – Modelling partial safety factor γmodelling: yielding where coefficient of variation of yield strength is less than 15 % |
| 27 | 5.5 Partial safety factor for resistance Table 4 – Modelling partial safety factor, γmodelling: fatigue of welded details and cast iron Table 5 – Minimum resistance partial safety factors, γM, for welded steel for different survival probabilities of the characteristic S-N curve Table 6 – Minimum resistance partial safety factors γM, for cast iron, forged and steel components (if not utilizing relevant design standards such as EN 1993-1-9) for different survival probabilities of the characteristic S-N curve |
| 28 | 5.6 Nacelle and hub component considerations 5.6.1 General 5.6.2 Hub structure and bolts Figures Figure 1 – Illustration of a nacelle structure, where for examplea direct drive generator is mounted behind the hub |
| 29 | 5.6.3 Nacelle front structure (alternatively: mechanical drive-train structure) 5.6.4 Gearbox structure 5.6.5 Yaw structure |
| 30 | 5.6.6 Nacelle rear structure 5.6.7 Nacelle cover and spinner 6 Deflection analysis |
| 31 | 7 Strength verification 7.1 General 7.2 Determination of stress and strain 7.3 Material properties 7.3.1 Material data |
| 32 | 7.3.2 Influence of size 7.4 Static strength assessment 7.4.1 Assessment process 7.4.2 Cast, forged and steel components |
| 33 | Figure 2 – Idealized elastic plastic stress-strain curve |
| 34 | 7.4.3 Welded structures 7.4.4 Bolted joints |
| 35 | 7.4.5 Fibre reinforced material 7.5 Fatigue strength assessment 7.5.1 Fatigue strength methods 7.5.2 Determination of local stresses 7.5.3 Stress hypothesis for fatigue |
| 36 | 7.5.4 S/N curves 7.5.5 Influence on fatigue strength Figure 3 – Representative S /N curve |
| 37 | 7.5.6 Partial safety factors for fatigue |
| 38 | 7.5.7 Damage accumulation Table 7 – Partial safety factors γM for S/N-curves of cast iron materials |
| 39 | 7.5.8 Bolted joints 7.5.9 Fibre reinforced material 7.6 Fracture mechanics assessment 7.6.1 General |
| 40 | 7.6.2 Define objective 7.6.3 Material parameter Figure 4 – Fracture mechanics calculation – process flow chart |
| 41 | 7.6.4 Defect model Figure 5 – Idealized crack types |
| 42 | 7.6.5 Structural model 7.6.6 Loading |
| 43 | 7.6.7 Strength assessment Figure 6 – Failure assessment diagram (FAD) |
| 45 | Figure 7 – Crack growth under cyclic loading by Paris/Erdogan |
| 46 | 7.7 Fracture mechanics-based design Figure 8 – Crack propagation and critical crack length in failure assessment diagram |
| 47 | 8 Material data for design from testing 8.1 Qualification of material 8.2 Derivation of static strength and impact energy properties (base material) 8.3 Derivation of fatigue strength properties (base material) |
| 48 | 8.4 Welded joints 8.5 Cast, forged and steel 8.5.1 Derivation of static strength properties 8.5.2 Fracture toughness |
| 49 | 8.5.3 Derivation of fatigue strength properties |
| 50 | 8.6 Bolts 8.7 Nacelle cover 9 Model verification and validation |
| 52 | Annex A (informative)Model verification and validation methods A.1 General A.2 Verification A.3 Validation (laboratory testing) A.4 Validation (field testing) |
| 53 | Annex B (informative) Welded joint stresses Figure B.1 – Fatigue analysis procedure for the weld toe |
| 54 | Annex C (informative) S-N curve determination by test, statistical evaluation and influencing factors C.1 General C.2 S-N curve C.3 Specimens C.4 Test procedure C.4.1 General |
| 55 | C.4.2 Finite lifetime C.4.3 Long life fatigue regime C.5 Influencing factors of S-N curve |
| 56 | Annex D (informative) Limit state equations D.1 General D.2 Yielding failure |
| 57 | D.3 Fatigue limit state equation |
| 59 | Figure D.1 – Haigh diagram with Re as the yield stress and Rm as the tensile limit |
| 61 | D.4 Fatigue assessment based on fracture mechanics Table D.1 – Representative stochastic model for fatigue analysis of cast iron |
| 64 | Annex E (informative) Load effect uncertainty computation Figure E.1 – Model example Table E.1 – Test cases combination |
| 65 | Table E.2 – Result comparison validation vs simplifiedmodels and ratio δmf calculation |
| 66 | Annex F (informative) Considerations for structural elements F.1 General F.2 Global and local failures Figure F.1 – Locations of failure for local (A) and global (B) failure |
| 67 | F.3 Mean stress influence Figure F.2 – Local and global failure for two different notch radii Figure F.3 – Haigh-diagram for evaluation of mean stress influence |
| 69 | Bibliography |
