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Improved Inspection of Composite Wind Turbine Blades with Accessible, Advanced Ultrasonic Phased Array Technology

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This presentation from ECNDT 2018 reviews the following topics:

Description of wind turbine blades
How ultrasonic phased array inspection works
The detection capabilities of ultrasonic phased array technology
The productivity of ultrasonic phased array technology
Conclusions

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Improved Inspection of Composite Wind Turbine Blades with Accessible, Advanced Ultrasonic Phased Array Technology

  1. 1. Improved Inspection of Composite Wind Turbine Blades with Accessible, Advanced Ultrasonic Phased Array Technology André Lamarre (andre.lamarre@olympus-ossa.com) Olympus Scientific Solutions Americas, Canada 12th ECNDT Conference, Gothenburg, Sweden, June 2018
  2. 2. Content § Description of wind turbine blades § How ultrasonic phased array inspection works § The detection capabilities of ultrasonic phased array technology § The productivity of ultrasonic phased array technology § Conclusions
  3. 3. Main Components of a Wind Turbine § Wind turbine blades – Generate aerodynamic torque from the wind § Nacelle – Converts the torque into electrical power § Tower – Holds the nacelle and rotor blades – Provides access to the nacelle § Foundation – Ensures that the turbine stays upright All these components require nondestructive testing to help ensure their integrity during manufacturing, construction, and maintenance. In this presentation, we focus on the use of ultrasonic phased array for inspecting wind turbine blades during manufacturing. Wind blade Nacelle Tower Foundation
  4. 4. What Is a Wind Turbine Blade? § A turbine blade is composed of an outer shell that is reinforced by one or many internal structural beams, also called spars § The number of spars depends on the size of the blade § The interior of the blade is hollow § Depending on the manufacturer, the spar could be an I-beam or a box
  5. 5. What Is a Wind Turbine Blade? § The I-beam spar is composed of 2 spar caps and one shear web § The box spar is composed of the 2 spar caps and 2 shear webs § The spar caps are attached to the the skin with adhesive § Materials – Glass-reinforced fiber, carbon-reinforced fiber, balsam/wood, adhesive, resins, honeycomb structures, and coatings – Most materials are not acoustic friendly
  6. 6. Manufacturing Flaws § Flaws can be the result of the blade’s design or occur during manufacturing § Types of flaws include: – Porosity – Disbonds – Delamination – Inclusions – The width of the adhesive and its position between the beam and shell – Wrinkles (out-of-plane waviness)
  7. 7. Principles of Ultrasonic Phased Array
  8. 8. Blade Inspection Using Ultrasonic Phased Array 4-element aperture 1 mm (0.039 in.) § Phased array probes are composed of multiple piezoelectric elements § Pulsing and receiving of the elements is electronically controlled to generate beams § Blade inspection is performed using linear scan beams
  9. 9. Data Point Density Low Density High Density § Higher density § Greater probability of detection Missed Detected
  10. 10. Large Effective Beam Conventional UT probe Phased array (64 elements) Larger coverage in one pass Finer resolution
  11. 11. Analysis Views Amplitude C-scan A-scan D-scan B-scan
  12. 12. Olympus Phased Array Instruments for Wind Blade Inspection OmniScan® SX Flaw Detector OmniScan MX2 Flaw Detector FOCUS PX™ Acquisition Instrument Manual and semi-automated inspection Semi and fully-automated inspection Portable One PA probe Portable Multiple PA probes PC-based Multiple PA probes Scalable
  13. 13. Low-Frequency Linear Phased Array Probes § Frequencies: 0.5 and 1 MHz § Number of elements: 64 § Length: 96 mm § Elevation: 22 mm § Pitch: 1.5 mm § Plastic housing to reduce the weight
  14. 14. Low-Frequency Linear Phased Array Probes § Mounted on 4 different wedges/probe holders § One with a semi-contact probe holder for deep penetration § One with an Aqualene delay line for improved near- surface resolution § Both probe holders are available as either curved or flat § All wedges/probe holders have water irrigation and an encoder attachment
  15. 15. The Detection Capabilities of Ultrasonic Phased Array
  16. 16. Example of a Spar Cap Inspection § Uses an automated scanner § OmniScan MX2 flaw detector § Olympus wind blade PA probe and wedge § Results presented as an amplitude C-scan Superimposed image for illustration purposes
  17. 17. § The C-scan below represents the ultrasonic mapping of the spar cap Example of a Spar Cap Inspection Bonded zones between the spar cap and shell Cross section Length Cross section Flanges § At CRP or GRP flanges, the ultrasound reflects off the inner side of the skin, resulting in a strong echo (represented in red on the C-scan) Nottoscale.Forillustrationpurposes § At bonded zones, if the bond is good, the ultrasound travels through the adhesive and disperses into the web, resulting in no or weak echo at the bonded interface (represented in blue or yellow on the C-scan)
  18. 18. § Using the amplitude C-scan image, we can: § Measure the width of the adhesive zones § Evaluate the quality of the bonds § Locate deficiencies in a bonded area § With the low-frequency phased array probe, the sizing resolution is 1.5 mm Example of a Spar Cap Inspection Bonded zones between the spar cap and shell Cross section Length Cross section Flanges Nottoscale.Forillustrationpurposes.
  19. 19. Bonding Evaluation § In this example, the bonded zone is deficient § The width of the bonded zone is getting narrow § An 80 mm long section is totally disbonded § Localized unbonded areas are also present in the good area – Approximate size: 20 mm × 20 mm
  20. 20. Adhesive Thickness Measurement § Depending on the adhesive material, echoes from the interface shell’s glue and the web’s glue are visible § The distance between these 2 echoes characterizes the adhesive thickness § Using the right velocity, the adhesive thickness can be evaluated
  21. 21. Delaminations § Delaminations between different GRP or CRP layers can be located § Good reflector of ultrasound § A time-of-flight C-scan is useful to discriminate between a geometry echo and delamination Delaminations Delaminations
  22. 22. Detecting and Sizing Wrinkles § Wrinkles are an out-of-plane alignment of layers § They reduce the blade’s tensile strength § Can create out-of-plane delaminations § Deviation in the vertical plane: 4 mm § Length of the wrinkle: 17 mm
  23. 23. The Productivity of Ultrasonic Phased Array
  24. 24. Using Automated Ultrasonic Phased Array to Inspect a Spar Cap Girder § OmniScan MX2 unit § Scanner length: 5 m; scanner width: 0.5 m § Scanning direction: length of the blade § Indexing direction: cross- section of the blade § 100 mm indexing § Acquisition resolution: 1.5 mm in both axes § 2 m2 inspected in 40 seconds § The C-scan and A-scan are both recorded The scanner is not an Olympus product.
  25. 25. C-scan Representation § OmniScan MX2 unit § Scanning direction: cross-section of the blade § Indexing direction: length of the blade; 100 mm indexing § Live mapping on the screen § Bonded zones and flanges are clearly visible
  26. 26. Conclusions § Ultrasonic phased array can be used to inspect wind blades with low-frequency probes (0.5, 1 MHz) § The 1.5 mm resolution enables small flaws to be detected and accurate flaw sizing § Flaws such as wrinkles, delamination, and disbonds can be detected and sized § The linear scan capability enables fast inspection while maintaining 100% coverage of the part
  27. 27. Conclusions § Off-the-shelf phased array units can be used as a standalone or integrated with automated scanners § C-scan imaging enables analysis at a glance § Use of A-B-C-D scans permit a more detailed interpretation § Data is archived § The use of ultrasonic phased array can also be considered in the maintenance program of wind turbine blades
  28. 28. Thank You Olympus and OmniScan are registered trademarks, and FOCUS PX is a trademark of Olympus Corporation.

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