Application of different ultrasonic techniques for non-destructive testing of the wind turbine blades

Transcription

1 The Open Access NDT Database Application of different ultrasonic techniques for non-destructive testing of the wind turbine blades E Jasiūnien, R Raišutis, R Šliteris, A Voleišis, A Vladišauskas Ultrasound Institute Kaunas University of Technology Lithuania

2 Objective To investigate and analyze different ultrasonic inspection techniques in order to detect as much as possible different defects in complicated composite structures.

3 Wind turbine blade sample 3

4 Full-width turbine blade sample 267mm d=5mm 412mm Flat-bottom holes 155mm 212mm Flat-bottom holes 138mm d=1mm 192mm d=5mm d=15mm 346mm 910mm Lightning Conductor 404mm 200mm d=10mm 285mm d=25mm 265mm d=20mm 140mm 104mm 100mm 75mm Trailing edge 67mm Upper shell Main spar (load carrying box) 257mm 85mm 57mm Leading edge Lower shell

5 Techniques Ultrasonic testing techniques, used for investigation of the wind turbine sample: Air-coupled testing f 0 =290 khz; Pulse-echo immersion testing (using moving water container): f 0 =2.2 MHz; f 0 =400 khz; Contact, with wedge type transducers (for investigation of leading edge); f 0 =500 khz.

6 Why so many different techniques? Because wind turbine blades: Are multilayered; Have variable thickness; Are made from anisotropic material; Have a lot of manufacturing nonhomogenities. 1 st layer (GFRP, skin-outer layer) 2 nd layer (glue) a b 3 rd layer (GFRP, wall of the main spar) Delamination Lack of glue c

7 Ultrasonic air-coupled technique Low frequency ultrasonic measurement and scanning system T R LLW Turbine blade sample The air-coupled technique using guided waves used for inspection of the wind turbine blades f 0 =290 khz

8 Ultrasonic pulse-echo immersion testing The experimental set-up for pulse-echo immersion testing of the wind turbine blade with planar 400kHz transducers. 3D mechanical positioning device (scanner) Ultrasonic measurement system Ultrasonic transducer, R 1 R 2 R 3 R 4 Computer with appropriate software for data acquisition and processing Water Reflected from internal structure Moving water container l 1 l 2 l 3 1 layer (GFRP skin) 2 layer (glue/foam) 3 layer (GFRP foundation) Segment of the multi-layered wind turbine blade

9 Pulse-echo immersion testing planar transducer 400kHz Parameters: Frequency 400 khz; Diameter 26 mm Scanning step 1 mm; Coupling liquid oil; Excitation 1 period burst; Amplitude 17 V. Gain 7 db.

10 20mm and 50mm defects on the main spar 267mm d=5mm 412mm Flat-bottom holes 155mm 212mm Flat-bottom holes 138mm d=1mm 192mm d=5mm d=15mm 346mm 910mm Lightning Conductor 404mm 200mm d=10mm 285mm d=25mm 265mm d=20mm 140mm 104mm 100mm 75mm Trailing edge 67mm Upper shell Main spar (load carrying box) 257mm 85mm 57mm Leading edge Lower shell

11 20mm and 50mm defects y, mm Air-coupled technique f 0 =290 khz Step 2mm 49mm 19mm Photo x, mm Pulseecho immersion testing f 0 =400kHz Step 1mm

12 80mm defect on the main spar 267mm d=5mm 412mm Flat-bottom holes 155mm 212mm Flat-bottom holes 138mm d=1mm 192mm d=5mm d=15mm 346mm 910mm Lightning Conductor 404mm 200mm d=10mm 285mm d=25mm 265mm d=20mm 140mm 104mm 100mm 75mm Trailing edge 67mm Upper shell Main spar (load carrying box) 257mm 85mm 57mm Leading edge Lower shell

13 80mm defect GFRP foundation layer Artificial defect Skin layer (dye coating with GFRP) Photo Natural defects (delaminations) Artificial defect Pulse-echo immersion testing f 0 =400kHz Step 1mm Natural defect - delamination/air inclusion (lack of epoxy glue/foam) Epoxy glue/foam layer Air-coupled technique f 0 =290 khz step 2 mm Artificial defect Natural delamination between skin surface and epoxy layer

14 15mm defect on the trailing edge 267mm d=5mm 412mm Flat-bottom holes 155mm 212mm Flat-bottom holes 138mm d=1mm 192mm d=5mm d=15mm 346mm 910mm Lightning Conductor 404mm 200mm d=10mm 285mm d=25mm 265mm d=20mm 140mm 104mm 100mm 75mm Trailing edge 67mm Upper shell Main spar (load carrying box) 257mm 85mm 57mm Leading edge Lower shell

15 15mm defect on the trailing edge Skin layer (dye coating with GFRP) Photo Artificial defect Epoxy glue/foam layer Air-coupled technique f 0 =290 khz Step 1mm

16 Conclusions Inspection is very relevant for control of product quality; Wind turbine blades are difficult object for investigation, because: Are multilayered; Have variable thickness; Are made from anisotropic material; Have a lot of manufacturing nonhomogenities Different techniques show different types of defects; Combination of different techniques gives best results!

17 Acknowledgements The part of this work was sponsored by the European Union under the Framework-6 Development of a Portable, High Energy, Nanofocus Computer Tomography system for Glass Reinforced Plastic Wind Turbine Blades CONCEPT (Computerised Open Environment Portable Tomography) project. CONCEPT is collaboration between the following organisations: TWI (UK), X-Tek (UK), Detection Technology (Finland), General High Voltage (UK), Innospexion (Denmark), Eon (UK), RWE npower (UK), Kaunas University of Technology (Lithuania), London South Bank University (UK) and Germanischer Lloyd (Germany). The project is coordinated and managed by TWI (UK) and is partly funded by the EC under the programme ref: COOP-CT

18 Ultrasound Institute Kaunas University of Technology Thank you for attention! Address: Studentų 50, LT Kaunas, LITHUANIA Phone: , Fax: , Home page: