Non Destructive Testing Methods in the Wind Power

Industry

Alison Glover, Tech Apps Specialist, OAZNicholas Bublitz, Product Support Manager Americas, ONDT

2Outline NDT definition Challenges in the Wind Industry

Issues requiring inspection Ultrasound

Conventional Phased Array

Eddy Current/ECA Other techniques

3NDT acronyms

NDT - Non Destructive Testing

NDI - Non Destructive Inspection

NDE Non Destructive Examination

4Non-Destructive Testing What is NDT?

Group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing permanent damage or alterations

Cf: Destructive Testing used to evaluate a specimen until or after its failure, eg Crash testing of vehicles Sectioning and micrography

5Why NDT? Cost effective

parts/equipment without defects not needlessly destroyed

repairs done only where needed (eg welds) Can be done

In manufacturing In service

Data for conditioning monitoring/service planning

6NDT Challenges in Wind Power Industry 1 Highly visible

Mass production fairly new lack of standards and case histories

Push for large, lighter, more productive units

7Challenges - 2 Many materials

Metals, composites (eg GRFP), wood

Access from one side only; top of towers

ConfidentialityBlade design is confidential

8Manufacturing and In-Service Issues 1 Blades

Delaminations, porosity, resin poor areas Thickness Adhesive failure Lightning Strikes

Porosity Delaminations

Composite Layers

9Manufacturing and In-Service Issues 2 Towers

Welds Lack of fusion Porosity Cracks Inclusions

Raw materials Laminations inclusions

10

Manufacturing and In-Service Issues 3 Nacelles/Mechanics

Assembly error Design Flaws Cracks Erosion/pitting

11

Remote Visual Inspection Gears, bearings,etc High resolution Still or video capture Highly portable Tool attachments eg

recovery

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Remote Visual Inspection

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What is Ultrasound?

Audible sound and UT are mechanical vibrations

UT is above frequency threshold of human hearing, ~20KHz

Typical NDT frequency range 500 KHz 20 MHz

14

Ultrasonics Thickness Testing Many materials metals,

plastics, GFRP, fibreglass Thickness, coating

thickness, corrosion, erosion, delamination

One-side access only Very accurate

15

Ultrasonic Flaw Detection 1 Largest application

weld testing Conventional or

Phased Array Manual to fully

automated

16

Phased Array BasicsPhased Array Basics

For electronic scans, same angle beam scans along the probe.

For sectorial scans, the Focal Laws are changed to give a range of angles.

17

Weldrover on Wind Tower Video

18

Advantages of Advanced Techniques PA + TOFD 20 OD tower

welds inspected in 2-3 minutes

Full data recording

19

Phased Array on Blades Increased detection Faster scanning than

conventional UT More intuitive displays Data storage

20

Phased Array on Blades 2

Manual or encoded

21

HRL: tower anchor bolt inspection Corrosion found in

submerged threaded section

Bolt had been in service >12 months

Validated PAUT Can inspection without

removing tower or nuts Uses Olympus Omniscan

& Eclipse Scientific bolt scanner

With thanks to Nick Kriesl, HRL Morwell

22

Eddy Currents Defects in the material disturb the circular path of the eddy

currents, changing the magnetic coupling with the probe and causing a variation in the impedance of the coil.

Magnetic Field in the coil

AC Current

Eddy Current

Magnetic Field in the test piece

Flaw

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Eddy Current Conventional or ECA Cracks Corrosion Conductivity

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Other Olympus Techniques: High Speed Video

Motion/impact/stress R&D

X-Ray Fluorescence Positive materials Identification (PMI) Materials sorting Fluid analysis and monitoring

25

Other NDT Techniques Liquid Penetrant Magnetic Particle (MP, FMP) Radiography (RT) Acoustic Emission Thermography And others.

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Some Considerations for NDT In house or service provider Training/certification Standards/codes Cost Suitability of methods

access, portability, material, flaw type and size, couplant, down time

No one perfect technique! Safety

Thank you