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Together, we make your blades stronger
Bladena’s new simple retrofit for increased
reliability and repair of the trailing ...
Together, we make your blades stronger
Agenda
• Short introduction to Bladena
• Trailing edge damages
• Effect of D-string...
Together, we make your blades stronger
• Spin out from Danish Technical
University, established 2011
• Seven patents makin...
Together, we make your blades stronger
Catastrophic trailing edge failures,
starts small
• Repairs can be costly and does ...
Together, we make your blades stronger
Root causes of trailing edge cracks are many
• Design system, verification system a...
Together, we make your blades stronger
Blade panel deformations induced
by edgewise gravity induced loads
during any opera...
Together, we make your blades stronger
Panel breathing and peel stress
• Peel stresses at the bond lines,
peels the adhesi...
Together, we make your blades stronger
Panel breathing accelerates crack
propagation through peeling and
necessitates regu...
Together, we make your blades stronger
D-String reduces breathing
(Deformation Limiting String)
Typically, ten strings
spa...
Together, we make your blades stronger
The D-String limits the
outward panels from
breathing, hence reducing
peel stresses...
Together, we make your blades stronger
First demonstration project
– rope access installation
Installed in Denmark in Janu...
Together, we make your blades stronger
First US Pilot Project
First pilot under installation in Texas
Platform access
Part...
Together, we make your blades stronger
First step: Size string by one time
measurement of panel deformation
Currently thre...
Together, we make your blades stronger
Estimating impact through measurements
Without D-
Strings
With D-Strings
installedT...
Together, we make your blades stronger
Easy Installation from platform or rope access
©Bladena 2013
Together, we make your blades stronger
Static safety against damage
to blade skin from D-string
• A comprehensive test pro...
Together, we make your blades stronger
Fatigue safety against damage to blade
skin from D-string
Measured
extreme event
Ty...
Together, we make your blades stronger
Increased reliability based on measured data
• Based on the in-situ measured deform...
Together, we make your blades stronger
Preventive or reactive use ?
Age Frequency of
damage
Action Result of D-string use
...
Together, we make your blades stronger
Next project: Cross-sectional shear
distortion was observed in the field
Measuremen...
Together, we make your blades stronger
Three new combined technologies making
blades stronger in the field
1) D-String
2) ...
Together, we make your blades stronger
©Bladena 2013
Thank you
Dr. Carsten Hein Westergaard
President, NextraTEC Inc.
Boar...
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Dr. Carsten Hein Westergaard: 2013 Sandia National Laboratoies Wind Plant Reliability Workshop

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Bladena's new simple retrofit for increased reliability an repair of the trailing edge bonds

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Transcript of "Dr. Carsten Hein Westergaard: 2013 Sandia National Laboratoies Wind Plant Reliability Workshop"

  1. 1. Together, we make your blades stronger Bladena’s new simple retrofit for increased reliability and repair of the trailing edge bonds Dr. Carsten Hein Westergaard President, NextraTEC Inc. Board member, Bladena Aps Bladena representative cw@nextratec.com Sandia National Laboratories Wind Reliability workshop 2013 August 13 – 14, 2013, Albuquerque Bladena US based service partners
  2. 2. Together, we make your blades stronger Agenda • Short introduction to Bladena • Trailing edge damages • Effect of D-string • Pilot projects • Installation • Recommendations • Future projects ©Bladena 2013
  3. 3. Together, we make your blades stronger • Spin out from Danish Technical University, established 2011 • Seven patents making blades stronger and more durable developed at RISØ (DTU) • Technology based on 10+ years of research & experience at DTU • Based in Denmark • Two Strong Service Partners in North America . ©Bladena 2013 D-String Simply effective! Bladena – the company Together, we make your blade stronger
  4. 4. Together, we make your blades stronger Catastrophic trailing edge failures, starts small • Repairs can be costly and does not eliminate the need for larger fleet repairs or replacement at a later stage • Significant risk for catastrophic failure remains, when the small cracks propagate unnoticed Unrepaired cracks lead to de-bonding Blade broken near max chord Trailing edge splitting ©Bladena 2013
  5. 5. Together, we make your blades stronger Root causes of trailing edge cracks are many • Design system, verification system and standards applied: – Non accommodating for critical errors; for example; lack of combined loads verification during testing – Exclusion of important failure mode combinations; for example, breathing of panels which leads to accelerated peeling • Manufacturing deficiencies: – Tolerances, random and/or systematic; for example, incorrect application of fibers – Quality deviations; for example, application of glue or curing of glue bond deviations • Unforeseen blade loading events: – Systematic; for example, by failure of sensors – Random occurrence; for example, induced by extreme weather events • Service methods – It is very difficult to detect hairline cracks, service methods can influence the root cause of failure mode development • Almost always, failure is a sequence or combination of these root causes ©Bladena 2013
  6. 6. Together, we make your blades stronger Blade panel deformations induced by edgewise gravity induced loads during any operation of any wind turbine makes the panels breath ©Bladena 2013 Panel breathing
  7. 7. Together, we make your blades stronger Panel breathing and peel stress • Peel stresses at the bond lines, peels the adhesive from the shells by stress concentration • Until peeling occurs, the stresses will create surface tension right at the trailing edge bond line eventually developing into (hairline) cracks • Trailing edge bonds are designed for shear stress, which occurs from blade bending during wind loading. • Peel stress is added to the shear stress ©Bladena 2013
  8. 8. Together, we make your blades stronger Panel breathing accelerates crack propagation through peeling and necessitates regular inspections and preventative repairs Hairline crack found at inspection Uptower repairs of trailing edge cracks ©Bladena 2013 It starts with hairline cracks
  9. 9. Together, we make your blades stronger D-String reduces breathing (Deformation Limiting String) Typically, ten strings spaced along the trailing edge limits the panel breathing, sufficiently ©Bladena 2013
  10. 10. Together, we make your blades stronger The D-String limits the outward panels from breathing, hence reducing peel stresses in the bond lines ©Bladena 2013 Without D-Strings With D-Strings installed Typical 10 D-Strings installed in max chord area Typical 10 D-Strings per blade Finite element model prepared for a specific blade sized by calibration with site measurements of the in- situ panel deformations
  11. 11. Together, we make your blades stronger First demonstration project – rope access installation Installed in Denmark in January 2013. ©Bladena 2013
  12. 12. Together, we make your blades stronger First US Pilot Project First pilot under installation in Texas Platform access Partners: ©Bladena 2013
  13. 13. Together, we make your blades stronger First step: Size string by one time measurement of panel deformation Currently three blades are documented with D- string implantation For other blades: A. Blade Survey to establish key dimensions of blade, and determine needs for step B&C B. Pilot, where loads and deformation levels are measured and installation methods are tested C. If needed: panel testing to establish panel strength D. Feasibility study establishes:  Suitable strength and fatigue life of panel and D-String  FEM simulation  Verify the effect of the D-String  Variations from a standard installation ©Bladena 2013 Step B: Measurements with temporary installed sensor from rope access, typically there are three places used to qualify D-string installation
  14. 14. Together, we make your blades stronger Estimating impact through measurements Without D- Strings With D-Strings installedTest on turbine, results from temporarily installed sensors Resulting analysis ©Bladena 2013
  15. 15. Together, we make your blades stronger Easy Installation from platform or rope access ©Bladena 2013
  16. 16. Together, we make your blades stronger Static safety against damage to blade skin from D-string • A comprehensive test program of the D-String has been performed at DTU, demonstrating safety margins against damage to the supporting blade skin foam sandwich • A string (fuse) is included for well defined protection at breaking point 1.5kN • Field test has shown measured string loads are very low, with peaks up to 0.4kN during emergency stops ©Bladena 2013
  17. 17. Together, we make your blades stronger Fatigue safety against damage to blade skin from D-string Measured extreme event Typical normal load situation Fuse ©Bladena 2013
  18. 18. Together, we make your blades stronger Increased reliability based on measured data • Based on the in-situ measured deformation and stress, the lifetime stress reduction can be calculated. By using Palgren-Miners, rule the life extension can be calculated • In the pilot projects, the measured improvement from the D-string is a 97% reduction in stress. This can be translated to: “If the blade was prone to cracks after 4 years, the life expectancy would be expanded to 40 years, i.e. a factor 10 in lifetime” Without D- Strings With D-Strings installed Resulting analysis based on measurements ©Bladena 2013
  19. 19. Together, we make your blades stronger Preventive or reactive use ? Age Frequency of damage Action Result of D-string use Reactive A few damaged blade(s) 1 to 4 years One time isolated event(s) Add D-string to blade repair • Avoid scrap • Additional safety in repair • “New” healthy blades in inventory • Direct savings Proactive Multiple damaged blades 2 to 10 years Multiple events, more than 1/200 rotors damaged per year Install D-string fleet wide on turbine type, preferably combined with blade inspection • Life extension through reduced stress in hairline cracks • Life extension far beyond 20 years for un-cracked blades • Preventive savings by reduced (eliminated) failure rate Preventive N/A No damage documented Install D-string fleet wide on turbine type • Strongly reduced sensitivity to manufacturing deficiencies or any other potential weaknesses • Statistical mean value moved far beyond 20 year life, so “no failures” will occur • Stronger blades Improved new built blades N/A Statistical variance of design Include D-string in new blade build ©Bladena 2013
  20. 20. Together, we make your blades stronger Next project: Cross-sectional shear distortion was observed in the field Measurements on a MW turbine showed cross-sectional shear distortion under normal operation Cross section shear, adds loading to the leading edge bond, and possible additional failures ©Bladena 2013
  21. 21. Together, we make your blades stronger Three new combined technologies making blades stronger in the field 1) D-String 2) X-Stiffener3) Floor 1) Stronger trailing edges 2) Stronger leading edges3) Strong root panels less prone to buckling ©Bladena 2013
  22. 22. Together, we make your blades stronger ©Bladena 2013 Thank you Dr. Carsten Hein Westergaard President, NextraTEC Inc. Board member, Bladena Aps Bladena representative cw@nextratec.com Bladena US based service partners Bladena US based service partners
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