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Neidigk: 2013 Sandia Wind Plant Reliability Workshop


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Evolution and Technology Transfer of Advanced Inspection Methods for Wind Turbine Blades

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Neidigk: 2013 Sandia Wind Plant Reliability Workshop

  1. 1. Stephen Neidigk Dennis Roach, Randy Duvall, Tom Rice Sandia National Labs August 14th, 2013 2013 Wind Plant Reliability Work Shop Evolution and Technology Transfer of Advanced Inspection Methods for Wind Turbine Blades Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000
  2. 2. Wind Blade NDI Test Specimen Library WINDIE Experiments and Inspection Results BSDS 9 Meter Fatigue Test Blade Inspections Presentation Overview On Blade Factory Testing Development and Testing of Automated and Semi-Automated Phased Array Inspections How NDI Relates to Reliability UT Inspection Methods
  3. 3. Objectives • Produce optimum deployment of automated or semi-automated NDI to detect undesirable flaws in blades (time, cost, sensitivity) • Transfer technology to industry through hardware and technology evaluation, inspector training, and procedure development Create the ability for manufacturers to determine the quality of their product before it leaves the factory Develop Evaluate Validate Transfer Potential nondestructive inspection methods for the detection of flaws in composite wind turbine blades
  4. 4. NDI in the Wind Industry • Different blade manufacturers use different inspection techniques, procedures and detection requirements. • Different blade designs • Varying manufacturing practices • Varying materials Post manufacturing in the plant In the field (up tower) Not necessarily the same hardware Spar Caps & Shear Web Box Spar & Shear Webs
  5. 5. Different composite materials and designs, but looking for similar manufacturing defects: • Laminate porosity • Interply disbonds • Adhesive voids and disbonds • Contaminates and foreign objects • In-plane and out-of-plane waves Early detection of manufacturing flaws enhances blade reliability NDI in the Wind Industry Thick Spar Structure Thick Adhesive Bond Lines Balsa or Foam Cores
  6. 6. 1 2 3 Spar Cap Spar cap back wall Adhesive back wall Slight Shift 3 2 1 Large Increase in Amplitude Large Decrease in Amplitude Example Bond Line Inspection (A-Scan)
  7. 7. Example Inspection (2 Dimensional C-Scan) X-Y Position EncoderA-Scan C-Scan High Amplitude Low Amplitude Gate
  8. 8. Phased Array verses Single Element Transducer Single Element Transducer A-Scan C-Scan Phased Array with Liner Encoder B-Scan A-Scan 16 Elements
  9. 9. Sandia Labs Wind Turbine Blade Test Specimen Library Additional large samples are housed at the Wind & Airworthiness Assurance NDI Validation Center (WAANC) hangar Added carbon sample set
  10. 10. NDI Feedback Specimens 1, 2 & 4 – Shear Web & Foam Core Specimens Laminate with Waviness and Dry Regions Foam Core with Disbonds and Delaminations Shear Web/Spar with Disbonds and Delaminations
  11. 11. Different Flaw Types Engineered into NDI Feedback Specimens (Examples) Glass Beads Grease Pillow InsertMold Release Materials inserted into multiple layers Voids in bond joint Glass beads In bond joint Dry fabric areasWaviness produced by pre-cured resin rods and stacked plies Pull tabs in bond joint Single ply of dry fabric
  12. 12. Fabrication of Carbon Feedback Specimens and NDI Reference Standards at TPI Flaws were placed at varying depths and locations using a template Line of various flaws at same depth Spar caps prior to bonding of shear web Blade assemblies developed for bond line inspection
  13. 13. Different Flaw Types Engineered into Carbon NDI Feedback Specimens (Examples) Dry Areas – Removed Resin Pillow Insert Grease Contamination Pre-Preg Backing Carbon Fuzz Ball Fiberglass FOD Adhesive Void Glass Microballoons in Bond Line Pull Tab Disbonds
  14. 14. Completed Carbon Feedback Specimens & NDI Ref Stds The set of specimens will be used to: • Develop and test NDI technology • Train inspectors and familiarize them with carbon material • Calibrate and set up NDI equipment • Ultrasonic flaw signal characterization • Inspection procedure development
  15. 15. Carbon Pre Preg Spar Inspection Challenges A-scan 40 mm. thick Fiberglass Gain – 55.2 dB Back Wall Increase gain to achieve 80% FSH Noise A-scan 40 mm thick Carbon Pre-Preg Gain – 55.2 dB 200x magnification A-scan 40 mm Carbon Pre-Preg Working with material manufacturers to ensure inspectability of their product Gain – 65.5 dB
  16. 16. Carbon Wind Blade Specimen Characterization C-scan produced by Omniscan Unit 1.5L16 (1.5 MHZ) 40mm Water Box REF-BLK-C2-TPI 75%75%75% CSPIFBH 75% GREASE 75% PB 75% PT 75% BOND 25% BOND INT 1INT 2 PTPTFBHFBH Gate 1: Spar Cap and Adhesive Shear Web Gate 2: Adhesive Shear Web
  17. 17. CH1 CH5 CH3 CH6 CH8 CH9 CH10 CH11 CH4 CH7CH2 CH12 CH13 9 Meter Fatigue Test Blade Inspections Flaw Location/Type Identifier
  18. 18. 9 Meter Blade Inspections (pre-fatigue) Note: Significant noise in signals (visible porosity) Flaw signals showing through noise Balsa Wood Shear Web Area Balsa Wood Inspections Included: MAUS V Pulse Echo UT Pulse Echo A-Scan Capture (over 500) OmniScan Phased Array Pulsed Thermography Vibro Thermography (Resodyne) Millimeter Wave Inspection Tool (POC) Laser Shearography (LTI) RotoArray Phased Array (GE)
  19. 19. WINDIE & 9 Meter Blade Inspections– Recent Inspections Physical Optics Corporation – Millimeter Wave Inspection Device Pillow Insert Detected in BSDS Blade
  20. 20. WINDIE & 9 Meter Blade Inspections – Recent Inspections Olympus - Phased Array Ultrasonics Full length scan capability Curvature Inspection Challenge
  21. 21. GE RotoArray – 1 MHz Rolling Phased Array WINDIE & 9 Meter Blade Inspections – Recent Inspections Ultrasonic C-Scan of 2.25 inch thick feedback specimen Ultrasonic B-Scan of fiberglass 9 meter blade Spar Cap Back Wall Adhesive/Spar Cap Back Wall As deployed on Omniscan vs. GE Phasor
  22. 22. Fatigue Test Blade Prior to Failure Inspections Inspections templates used to relocate the exact point where the initial measurements were taken. Out of plane wave at 3750 mm on the HP side induced: • Large delamination the width of the spar cap • Cracks perpendicular to the spar in the matrix
  23. 23. 24G-HP-OPW-SC-3750-18-A A BD C 24G – C Pre 24G – D Pre 24G – C Post 24D – D Post Signal Shift and Amplitude Decrease Signal Shift and Amplitude Decrease
  24. 24. 75% (ON PLIES 9-11) 50% (ON PLIES 19-21) 25% (ON PLIES 29-31) INTERFACE 1 AA B B 2.00" DIA 1.00" DIA 50% (ON PLIES 19-21) 25% (ON PLIES 29-31) 75% (ON PLIES 9-11) 2.00" DIA 1.00" DIA 1.65" DIA 1.15" DIA 1.00" DIA 2.50" DIA 2.50" DIA 1.00" DIA 2.50" DIA 1.00" DIA 2.00" DIA 2.00" DIA 2.50" DIA 1.00" DIA 1.00" DIA 2.00" DIA 2.00" DIA 2.00" DIA 2.00" DIA 2.50" DIA 1.00" DIA 2.50" DIA INTERFACE 2 Probe Frequency & Type Analysis 500 KHZ vs. 1 MHz Contact vs Focused Spar Cap = 2.14” th Adhesive Bond Line = 2.65” th. Balancing Clarity with Depth of Penetration 500 KHz Contact1 MHz Contact 1 MHz Focused Probe
  25. 25. Gate Setting Analysis MAUS V 500 KHZ Contact Test C-Scan Results Defects at the shear web flange and adhesive layer may, or may not, be detected depending on gate settings and part thickness. Adhesive Back Wall Laminate and Adhesive Back Wall
  26. 26. Probe Housing Development for Factory Deployment Sandia has focused on two water box deployment options: • Adjusts to slight curvature surfaces • Maximizes signal strength • Accommodates necessary standoffs for signal clarity • Easily saves scanned images for reference using the unidirectional Mouse encoder • Either sealed or pierced bladder construction 4 Ply Pillow Inserts FBH FHB’s Pillow Inserts
  27. 27. On-Blade Testing in Manufacturing Facility 36 Meter Station Scanning Direction Higher Amplitude Scan Area Spar Cap Back Wall Adhesive Back Wall
  28. 28. On-Blade Testing in Manufacturing Facility 16 Meter Station on Fiberglass Spar Cap Blade Spar Cap Cross Section Schematic Showing the Spar Cap, Adhesive Bond Line and Shear Webs Scanning Direction Vertical Strip C-Scan Image Showing Adhesive Void in Upper Bond Line Adhesive Void Between Spar Cap and Shear Web Sealed water box and 1.5L16 Phased Array probe was used to detect missing adhesive in bond lines
  29. 29. Wind Blade NDI Program Results at Sandia NDI Test Specimen Library including: • Full-scale test specimens • Fiberglass and carbon specimens with engineered defects ranging in thickness up to 2.5 inches • Feedback specimen and reference standard development • Statistically valid, blind probability of detection experiment Developing enhanced NDI methods for wind blades • Improved signal to noise and image resolution (improved flaw detection) • Factory deployment Evaluation of various NDI technologies on standardized specimen set (WINDIE – worked with 22 different NDI developers) • Assessment of multiple methods to comprise NDI tool box Early detection of manufacturing flaws enhances blade reliability
  30. 30. Stephen Neidigk Sandia National Labs (505)284-2200