Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

New Ideas, Methods and Materials for Improving Blade Repairs

1,454 views

Published on

Wind turbine blades need regular inspections and maintenance just like the rest of the turbine. While drones with high-res cameras may speed inspections, repairs will still be done with wind technicians on platforms and ropes. In this webinar Lou Dorworth of Abaris Training explores methods for repairing several types of common repairs, and Tony Gray will discuss the materials that best complete the work and more.

Published in: Engineering
  • Be the first to comment

New Ideas, Methods and Materials for Improving Blade Repairs

  1. 1. #WindWebinar New Ideas, Methods and Materials for Improving Blade Repairs
  2. 2. #WindWebinar q  This webinar will be available afterwards at www.windpowerengineering.com & email q  Q&A at the end of the presentation q  Hashtag for this webinar: #WindWebinar Before We Start
  3. 3. #WindWebinar Paul Dvorak Moderator Windpower Engineering & Development Tony Gray Key Account Manager -Wind Energy Sika Corp. Lou Dorworth Direct Services Division Manager Abaris Training Resources Inc. New Ideas, Methods and Materials for Improving Blade Repairs Meet your presenters…
  4. 4. Introduc)on   •  Turbine  blade  damage  requires  the  applica)on  of   simple  but  func)onal  repairs  given  the  physical   difficulty  of  the  task     •  The  most  common  opera)onal  damage  is  from  surface   impact  and  rain/dust  erosion     •  Other  damage  from  bird  strike,  lightning  strike,  other   object  impact,  and/or  the  propaga)on  of   manufacturing  anomalies       •  The  repair  methods  and  materials  need  to  be  simple   but  effec)ve  in  order  to  maintain  the  blade’s   structural  integrity  and  future  opera)onal   effec)veness      
  5. 5. Types  of  Damage  &  Common  Repairs   •  Erosion  damage  (without  major  fiber  damage)   –  Abrade,  clean,  fill  &  fair  with  suitable  epoxy  or  polyurethane  filler   •  Minor  scratches  or  dings  affec)ng  surface  ply   –  Abrade,  to  remove  paint  around  damage  down  to  the  laminate  surface,  fill  scratch  or  ding  with  filler  paste  &   apply  1-­‐layer  of  fine  glass  fabric  with  epoxy     •  Damage  into  or  beyond  outer  ply  of  laminate   –  Remove  and  replace  damaged  plies  or  apply  a  bonded  doubler  repair   •  Damage  into  sandwich  core  structure   –  Remove  &  replace  damaged  core  and  structural  plies  in  damaged  skin  or  apply  doubler  repair   •  Damage  through  structure   –  Remove  damage  through  structure  and  repair  from  both  sides  (if  accessible)  using  repair  plies  or  doublers   •  Op)on:  Repair  from  one  side  using  “no  backside  access”  techniques   Note:  all  repair  types  are  “zone  dependent”  requiring  aerodynamic/aeroelas)c  considera)ons  
  6. 6. Cri)cal  Aerodynamic  Areas     Aerodynamic  Loading  of  Wind  Turbine  Blades    
  7. 7. Laminar  Flow  and  Boundary  Layer   Note  the  change  in  laminar  flow  as  angle  of  aZack   (blade  pitch)  changes  in  model  at  right    
  8. 8. Blade  Repair  Zones   1 2 34 Repairs  to  turbine  blades  require  considera)on  of  aerodynamic  and   aeroelas)c  loads  on  the  structure  –  repair  design  and  approach   may  be  adjusted  to  meet  zone  requirements  
  9. 9. Blade  Repair  Zones   Zone  1.    For  both  for  aerodynamic  and  structural  purposes;  the  blade  leading  must  be  maintained  for  the   laminar  boundary  layer.    Zone  1  is  from  the  20%  to  100%  span  length  and  to  25%-­‐30%  of  the  local   chordline.    Zone  1  will  always  require  a  flush  repair.     Zone  2.    For  aeroelas)c  purposes;  do  not  add  significant  weight  to  this  zone  of  the  blade,  so  as  to  maintain   mass  balance.  Not  a  major  structural  region  of  the  blade,  however  the  repair  needs  to  be  an   aeroelas;c  semi-­‐structural  repair.       Zone  3.    Primarily  for  aeroelas)c  purposes;    the  repair  does  not  necessarily  need  to  be  flush  for  airflow   aerodynamics,  but  it  must  not  add  significant  weight  behind  the  shear  center.    However,  trailing   edge  repairs  are  typically  flush  for  aeroelas;c  requirements.       Zone  4.    Not  required  to  be  aerodynamically  smooth,  but  may  need  to  be  a  semi-­‐structural  or  structural   repair  based  on  the  severity  of  the  damage  and  the  proximity  of  the  damage  to  the  main  load   bearing  region  of  Zone  4  (i.e.  spar  cap).    Because  of  the  large  enclosed  area  of  the  blade  in  Zone  4   the  torsional  rigidity  is  much  higher  than  loca)ons  in  Zone  3  and  aeroelas)c  requirements  are  not   necessarily  cri)cal.  (Note:  significant  damage  to  Zone  4  training  edge  may  need  a  flush  semi-­‐ structural  repair.)  
  10. 10. Leading  Edge  Erosion   •  Most  common  type  of  damage   to  most  cri)cal  part  of  the   aerodynamic  airfoil   –  May  or  may  not  require  structural   ply  replacement   •  Common  approach  is  to  repair  is   to  fill  and  fair  back  to  smooth   aerodynamic  surface   –  Abrasion  of  damage  and   surrounding  area  prior  to  fill  &   fair  with  epoxy  or  polyurethane   paste  
  11. 11. Stepped  Removal  &  Repair   •  Each  damaged  layer  is  removed  in   “steps”  so  as  to  provide  a  landing  for   each  replacement  layer  in  the  repair.   –  Usually  bulk  mul)-­‐axial  material;  repaired   bulk  ply  for  bulk  ply.   •  Step  removal  almost  always  results  in   damage  to  underlying  structure   •  Each  bulk  repair  ply  then  overlaps  the   corresponding  exposed  layer  in  the   structure.     –  Faying  surfaces  do  not  match  axial   orienta)on  requirements  
  12. 12. Typical  Stepped  Repair   Loads  are  distributed  through  the  repair  via   a  lap  joint  into  the  underlying  layers   The  resul)ng  repair  sits  above  the  surface   Copyright  ©  Abaris  Training  2015   Filler  Ply  
  13. 13. Typical  Stepped  Repair   Shear  stress  distribu)on  in  a  stepped  repair     Note  peak  stress  concentra)ons  at  edges  of  each  step-­‐lap  within   the  repair     Copyright  ©  Abaris  Training  2015   Filler  Ply  
  14. 14. Tapered-­‐Scarf  Repairs   •  A  tapered-­‐scarf  angle  is  machined   through  the  composite  structure   so  as  to  expose  each  layer  along  a   gently-­‐angled  slope.   •  Each  repair  ply  then  lays  over  the   corresponding  exposed  layer   along  the  tapered  angle.   –  Recommend  mul)ple   unidirec)onal  materials  for   replacement  of  each  mul)-­‐axial   bulk  ply  
  15. 15. One  Tri-­‐axial  =  Three  Unidirec)onal  
  16. 16. Typical  Tapered-­‐Scarf  Repair   Loads  are  transferred  directly  through  the    edges  of  each   unidirec)onal  element  of  the  mul)-­‐axial  layer,  in  plane,  on  axis,   in  shear,  matching  that  of  the  underlying  structure     The  resul)ng  repair  is  flush  with  the  surface  
  17. 17. Typical  Tapered-­‐Scarf  Repair   Uniform  shear  stress  distribu)on  through  a  tapered  scarf   joint    
  18. 18. Trailing  Edge  Scarf  Repair   Damage   Damage  removal  &  scarf   Final  repair  
  19. 19. Vacuum  Bagging  &  Curing  the  Patch   •  Vacuum  bag  with  bleeder  &   breather  layers     –  Facilitates  compac)on  of   the  repair  plies   •  Heat  blanket  with   thermocouples  and  process   controller     –  Used  to  accurately  control   cure  temperature  
  20. 20. Typical  Heat  Blanket  Layup  Scheme   Breather/Insula;on   Vacuum  Bag  
  21. 21. - Apply a minimum of 22 in Hg vacuum and maintain throughout cure cycle *Heat at 1-5°F/Min *Cool at <5°F/Min *Hold at 150°F ± 10°F x 60-70 mins * Temp based upon lagging thermocouple Typical  Cure  Cycle  Recipe  Based  on  two-­‐part  amine  cured  epoxy  resin  chemistry  
  22. 22. Post-­‐Repair  Finishing   Gel  Coat   Filler  Paste   Care  is  taken  to  prevent  sanding  into  underlying  repair   plies  
  23. 23. CHOOSING  THE  RIGHT  MATERIALS  FOR  BLADE  REPAIRS    TONY  GRAY   KEY  ACCOUNT  MANAGER  –  WIND  ENERGY   GRAY.TONY@US.SIKA.COM   (574)  361-­‐8424    
  24. 24. 24  |   SIKA  CORPORATION   A  LITTLE  ABOUT  US…   §  Sika  is  a  world  leader  in  construc)on  chemicals   §  Speciality  chemical  products  in  automo)ve  &  industrial   markets   8/18/15   |  Sika  Industry  -­‐  Inven)ng  the  Future  
  25. 25. 25       §  Factors  in  Making  a  High   Quality  Repair   §  High  Quality  Repairs  in  Less   Time   TOPICS   25
  26. 26. 26       KEY  FACTORS  IN  MAKING  A  HIGH  QUALITY  REPAIR     Mixing and application Curing and finishing Suitable product Environmental conditions! Substrates & Surface Preparation
  27. 27. 27       SUITABLE  PRODUCT         Critical damage in main body of blade   Half way or entirely through 1st ply of fibreglass Structural Damages Surface Damages   Non-structural damage of surface   Less than half way through 1st ply of fibreglass Ø  2C laminating resin + suitable glass fibre fabric Ø  2C surface filler Polyester  resin  &  filler  –  Polyester  blades  only!   Epoxy  &  Urethane  –  Good  for  all  blade  types  
  28. 28. 28       KEY  FACTORS  IN  MAKING  A  HIGH  QUALITY  REPAIR     Suitable product Environmental conditions!
  29. 29. 29       ENVIRONMENTAL  CONDITIONS     Temperature… Humidity…   High influence on 2C products   Moderate influence on 2C products High temperatures… à  shorten pot life & cure times (quicker sanding, grinding etc.) Refer to the Product Data Sheet for Application Temperature & Humidly Range Typical Repair Products: →  Applica)on  temperature:    18C  (64F)  –  25C  (77F)   →  Max  humidity  –  70%  RH  
  30. 30. 30       KEY  FACTORS  IN  MAKING  A  HIGH  QUALITY  REPAIR     Mixing and application Suitable product Environmental conditions! Substrates & Surface Preparation
  31. 31. 31       MIXING  &  APPLICATION     Wrong mixing may lead to…   Too Short application time   No or insufficient curing   Too long curing time   Bad end properties (e.g. soft or brittle material) Correct mixing ensures…   Sufficient application time   Correct curing speed and homogeneous and full curing   Good end properties after curing & durability LJ
  32. 32. 32       KEY  FACTORS  IN  MAKING  A  HIGH  QUALITY  REPAIR     Mixing and application Curing and finishing Suitable product Environmental conditions! Substrates & Surface Preparation
  33. 33. August  18,  2015  33       CURING  &  FINISHING     Curing behavior - Resins ž  To reach OEM durability a resin repair must be post cured. ž  Post curing raises the Tg of the resin. Takes the resin from a glassy (brittle) state to a flexible (rubbery) state. ž  Tg should always be higher than operating temperature of the blade ž  Typical OEM spec is 75°C – 80°C (167°F - 176°F) Curing behavior - Fillers ž  Some fillers need multiple coats to build thickness. ž  Application temperature has a large affect on the open time & sanding time. ž  Not all fillers sand the same.
  34. 34. 34       KEY  FACTORS  IN  MAKING  A  HIGH  QUALITY  REPAIR     Mixing and application Curing and finishing Suitable product Environmental conditions! Substrates & Surface Preparation
  35. 35. August  18,  2015  35       HIGH  QUALITY  REPAIR  IN  LESS  TIME     ž   Buy  your  products  from  a  name  that  you  can  trust       ž   Chose  the  wind  repair  products  that:   1.  Give  the  largest  temperature  &  humidity  applica;on   window   2.  Cure  fast   3.  Are  easy  to  mix        
  36. 36. 36       HIGH  QUALITY  REPAIR  IN  LESS  TIME   TEMP  &  HUMIDITY  APPLICATION  WINDOW   Sika  Specialty  Wind                                   Repair  Products   §  Specialized  products  for  up     tower  blade  repair     §  Applica)on  temperature                     5C  (40F)  –  35C  (95F)   §  Max  humidity  –  80%  RH   Currently  available  repair  season   Extended  repair  season   Average  min  &  max  temp  (Northern  US)   Commonly  Used   Wind  Repair  Products   §  General  purpose  made  for    shop   environment.   §  Applica)on  temperature                   18C  (64F)  –  25C  (77F)   §  Max  humidity  –  70%  RH  
  37. 37. 37       HIGH  QUALITY  REPAIR  IN  LESS  TIME   CURING  FAST   Commonly  Used                                     Wind  Repair  Products     §  Resin  has  long  post  cure  )mes   depending  on  resin  type  used   §  Mul)ple  applica)ons  of  filler  must  be   made  to  build  thickness  and  fill  pin   holes   §  Filler  sand  )mes  can  be  lengthy   depending  on  type  used,  especially  at   cold  temperatures   Sika  Specialty  Wind                                   Repair  Products   §  Resin  has  fast  post  cure  )mes.    Post   cure  in  as  liZle  as  30  minutes  to  reach   OEM  spec  Tg   §  Thixotropic  filler  materials  that  builds   thick  layers  with  a  smooth  finish  in   one  applica)on.   §  Filler  sand  )mes  of  35  minutes  or  less   down  to  5C  (40F)  
  38. 38. August  18,  2015  38       HIGH  QUALITY  REPAIR  IN  LESS  TIME   EASY  TO  MIX   Commonly  Used                                     Wind  Repair  Products   §  Cans  of  A  &  B  components  that   must  be  mixed  onsite  to  reach   correct  ra)o  ()me  consuming  &   error  prone)       Sika  Specialty  Wind                                         Repair  Products   §  Ready  to  go  A/B  foil  packs  (Resin)   §  Side  by  side  or  coaxial  cartridges  with   sta)c  mixer  (Fillers)   §  Cartridges  save  material  by  only   dispensing  what  is  required    &  can  be   used  on  mul)ple  repairs   §  Tendency  to  mix  more  than  is     required  –  causes  excess  waste  
  39. 39. August  18,  2015  39       SIKA  SPECIALTY  WIND  BLADE  REPAIR  PRODUCTS     Epoxy  Repair  Resin   Polyurethane  Fillers   Sikadur®  Blade  Repair  Kits   Sikaforce®  7800  Red  &  Blue   Hybrid  UV  Resistant  Sealant  
  40. 40. #WindWebinar Paul Dvorak Managing Editor Windpower Engineering & Development pdvorak@wtwhmedia.com New Ideas, Methods and Materials for Improving Blade Repairs Lou Dorworth Direct Services Division Manager Abaris Training Resources Inc. lou@abaris.com Questions? Tony Gray Key Account Manager – Wind Sika Corp. gray.tony@us.sika.com
  41. 41. #WindWebinar Thank You q  This webinar will be available at www.windpowerengineering.com & email q  Tweet with hashtag #WindWebinar q  Connect with Windpower Engineering & Development q  Discuss this on EngineeringExchange.com

×