dayton griffin - current status and ongoing development of wind turbine blade standards
TRANSCRIPT
DNV GL © 2014 SAFER, SMARTER, GREENERDNV GL © 2014
Wind turbine Blade Standards:
August 31, 2016
ENERGY
19 September 20161
Current Status and ongoing developments
Dayton A. Griffin
DNV GL © 2014
Agenda
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1. Legacy blade standards
2. Introduction to IEC 61400-5
3. Primary Technical Challenges§ Intro to “Limit States” design methodology§ Safety factor approach for current existing standards
§ Toward a “physics-based” approach to safety factors
4. Summary
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Current / legacy blade standards
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61400-22 (2010)Wind Turbines – Part 22: Conformity Testing and Certification
61400-1 Ed. 3 (2003)Wind Turbines – Part 1: Design Requirements
61400-23 Ed.1 (2014)Wind Turbines - Part 23: Full Scale Structural Testing of Rotor Blades
61400-5 (draft, 2013)Wind Turbines – Part 5: Design and Manufacturing of Rotor Blades
Legacy IEC Standards for Blade Design, Manufacture and Test
Technical specification (TS) now revised / released as standard.
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Legacy Blade Standards
§DNV-DS-J102 Standard (2010)–Supplements standards in current IEC system
§GL Guideline for the Certification of Wind Turbines (2010)–Used as stand-alone standard, or with relevant IEC documents
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Current DNV GL Blade Standard
§Published December 2015§Harmonization of legacy DNV and GL requirements
§Draws on philosophy / approach from IEC working group
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Introduction to IEC 61400-5
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IEC Standards for Blade Design, Manufacture and Test
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What were you guys thinking????
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What were you guys thinking????
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Purpose / Scope
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§ Ensure engineering integrity of wind turbine blades§ Appropriate level of operational safety for design lifetime§ Requirements for:
– Aerodynamic and structural design– material selection, evaluation and testing– Manufacture, including quality management
– Transportation, installation, operation and maintenance (including repair)
§ Potential uses:
– Technical reference– Certification
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PT-5 worldwide participation
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IEC61400-5 Document Summary - contents
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IEC 61400-5 Drafting Process
§61400-5 approved as new work item by Chinese National Committee
§Kick-off October 2009 in Geneva§Meetings have alternated between Europe and Asia§16 regular + several “sub-group” meetings to date§ Due to time taken in drafting, IEC required the standard to be submitted as new work item proposal (NP)
§ PT5 submitted NP along with Committee Draft (CD) of the standard June 29, 2016
§ Votes on NP and comments on CD due from National Committees September 30, 2016
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Primary Technical Challenges
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Current state-of-the-art blade design and analysis
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“Permissible” Methods “State-of-the-Art” Methods2-D “section” analyses 3-D Finite Element Analyses
Loading in 4 primary directions(can be decoupled and applied independently)
Loading in at least 12 directions(i.e. stress/strain response in 12 directions due to simultaneous application of MFlap, Medge…)
Fatigue using design-equivalent load (DEL) - Markov Matrices- “Unit stress response function” + time-series
loading
Classical buckling analysis - Linear Eigenbuckling- Non-linear buckling
Limit States Design method - Probabilistic methods- Damage tolerant design
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Known shortcomings for current standards / methods
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In principle, partial safety factors
related to uncertainties
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IEC Design Value of Load IEC Design Value of Blade Strength, including partial factors for materials and consequences of failure
Characteristic Value of Coupon Strengths (e.g, 95% exceedance)
Coupon StrengthDistribution
Characteristic Value of Load
Expected LoadDistribution
LOADS (STRESS) STRENGTHS
n* m
Mr
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Known shortcomings for current standards / methods
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In principle, partial safety factors
related to uncertainties
In practice, little relationship to
actual uncertainties
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Known shortcomings for current standards / methods
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In principle, should use “pyramid” design approach
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Known shortcomings for current standards / methods
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In principle, should use “pyramid” design approach
In practice, current methods only use top and bottom of pyramid
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Partial Safety Factors in Draft 61400-5
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m = m0 m1 m2 m3 m4 m5 1 2 Where: 3
m0 “Base” material factor (to be included in all analyses) 4
m1 Environmental degradation (non reversible effects) 5
m2 Temperature effects (reversible effects) 6
m3 Manufacturing effects 7
m4 Computation and validation methods 8
m5 = Resolution of load components 9
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Example Partial Material Safety Factor (PMSF) Selection –Laminate Ultimate Strength
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PMSF,
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Summary
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Summary
§Drafting process has been 6 ½ years§CD submitted along with NP June 2016§ Votes and comments due Sept. 2016§Working group has committed to attempt a “physics-based” approach to partial safety factors
– Intent is to have standard provide a path to reward “responsible innovation”– It will be difficult to implement – but we need to try!
– We expect this draft to be very controversial
§Opportunities for U.S. stakeholder input:– By email at any point in process– “Stakeholder Committee” meeting Sept. 1, 8:00–10:00 AM
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SAFER, SMARTER, GREENER
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Any Questions?
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+1 425 422 [email protected] A. Griffin