Cone type Phased Array Design for High Speed Hollow Axle Inspection

Transcription

1 ESIS TC24 Workshop: Integrity of Railway Structures Cone type Phased Array Design for High Speed Hollow Axle Inspection Rainer BOEHM 1, Thomas HECKEL 1, Michel BLANKSCHÄN 1, Wolfgang SPRUCH 2, Toni BEGGEROW 2 1 Bundesanstalt für Materialforschung und -prüfung (BAM), Berlin, Germany 2 Büro für technische Diagnostik BTD, Brandenburg, Germany Contact rainer.boehm@bam.de Abstract To increase inspection speed and inspection reliability the use of phased array system is a superior solution. Especially for shaft inspection phased array setups are commonly used. For hollow axle inspection typically a number conventional probes rotating through the axles drilling are applied, without demounting the axes and without dismantling the wheels and the brake discs. A new approach using a cone type array operated in immersion technique will allows to increase inspection speed and reduce the mechanical effort of the inspection system by rotating the sound field for the circumferential scan electronically. Only a linear movement of the probe is necessary to move the phased array cone forward and backwards inside the drilling. By applying additional focal laws the beam can be inclined exactly and be focused in the plane vertical to the specimen axis to concentrate the sound in the zones close to the external surface of the railway axle. The cone type phased array probe has been optimized to detect transversal flaws in and close to the outer surface of the hollow axle, whose surface lies in the radial-radial plane. The prototype probe system and its performance will be presented. License: 1

2 2017/09/26 PRESENTATION CONE TYPE PHASED ARRAY DESIGN FOR HIGH SPEED HOLLOW AXLE INSPECTION R. Boehm 1, T. Heckel 1, M. Blankschän 1, W. Spruch 2, T. Beggerow 2 1 BAM, Bundesanstalt für Materialforschung und prüfung, Berlin, Germany 2 BTD, Büro für Technische Diagnostik, Brandenburg, Germany

3 CONTENT Task Principle of the scanning technique Prior developments New array design Conclusion New Array Design for Electronic Rotation Scanning Page 2

4 TASK Rail axle with longitudinal bore hole and test zones Page 3

5 TASK bore hole transversal flaw test region Orientation of transversal flaw in the radial radial plane Page 4

6 PRINCIPLE OF THE SCANNING TECHNIQUE Hohlwelle Axle Array Schwingerelemente Elements Flüssigkeit Fluid Hohlwelle Axle Bore hole Ø 65 mm Conical Kegelarray array inmitten centered der Bohrung in Ø the 65 mmhole Electronic rotation Schallbündelrotation Sketch of the cone shaped phased array for electronic rotation scan Page 5

7 RESULTS OF PRIOR STUDIES First cone array shown at ECNDT 2006 Büro für Technische Diagnostik (BTD) Bore hole Ø = 30 mm and Testing zone Calculated sound fields Calculated sound fields in the plane of incidence and perpendicular thereto Page 6

8 RESULTS OF PRIOR STUDIES Cone array system encapsulated in an oil cavity for simultanious testing in foreward and backward direction; developed in the project WOLAXIM 2012 Page 7

9 NEW DESIGN Upper cone diameter 60 mm Max. element length Cone angle = 2 b b depends on the angle of incidence Element Bore hole Ø = 65 mm Lower cone diameter 20 mm Geometrical boundary conditions for the current task Page 8

10 SOUND FIELD SIMULATION Bore hole Active elements Focal point (example) Position for calclation The position of the array in the bore hole and the line of computation points circumferential at the outer surface of the axle with Ø = 175 mm Page 9

11 SOUND FIELD SIMULATION, FOCUSING Normalized amplitude unfocused Fluid Axle Circumferencial angle position in Sound beam Directivity of the array with 13 active elements from 108 in total Page 10

12 SOUND FIELD SIMULATION, FOCUSING Normalized amplitude focussed grating lobes -17 db amp. -34 db echo Fluid Axle Circumferencial angle position in Sound beam Directivity of the array with 13 active elements from 108 in total, focusing in circumferential direction, focus at the surface of the axle Page 11

13 SOUND FIELD SIMULATION, FOCUSING Normalized amplitude grating lobes Focal points at 0, 10, 20 and 30 1 µs Main beam Grating lobe Circumferencial angle position in Amplitudes at different swivel angles in relation to the grating lobes Pulses and spectra at 0 and -20 for the focal point at 0, normalized amplitudes Page 12

14 SOUND FIELD SIMULATION, NUMBER OF ELEMENTS Amplitude Position = Amplitude active el., bw = active el., bw = active el., bw = active el., bw = Circumferencial angle position in Directivity of single elements of an array with 17 active elements Circumferencial angle position in Amplitude and divergence angle bw with different numbers of active elements Page 13

15 SOUND FIELD SIMULATION, ROTATION SCAN Normalized amplitude el. shift, Middle position Normalized amplitude 1 el. shift, steering to -1.7 Middle position Circumferencial angle position in Circumferencial angle position in Rotation of the sound field by shifting the group of active elements and by focal law Page 14

16 SOUND FIELD SIMULATION, FOCUSING II Normalized amplitude unfocused focussed Element length in mm Concave curved elements for focusing in the plane of incidence Page 15

17 SOUND FIELD SIMULATION, FOCUSING II Normalized amplitude Beam divergence in unfocused focussed Element length in mm unfocused focussed Element length in mm Concave curved elements for focusing in the plane of incidence Page 16

18 SOUND FIELD SIMULATION, FOCUSING II mm Curved elements 5 mm 2 Plane elements 5 mm angle of incidence a in Cross section of the beam at the axle surface focused and unfocused Page 17

19 SOUND FIELD SIMULATION, FOCUSING II Line perpendicuar to the plane of incidence Cut of the plane of incidence Cross section of the focused beam at the axle surface -3 db -6 db -12 db Expected echo height 2 mm Page 18

20 NEW DESIGNED PHASED ARRAY SYSTEM Page 19

21 CONCLUSION Properties of the new cone type phased array, (earlyer versions) Probe is optimized for a bore hole diameter of 65 mm Higher frequency, 4 MHz (2.7 MHz) Maximum cone diameter 60 mm (28 mm) More elements, 108 (48) Narrower elements, 1 mm (1.25 mm) Longer elements, 25 mm (12 mm) Focussing in the plane of incidence with curved elements Nearly cycle shaped beam, or adaptable beam divergence in circumferencial direction All this results in higher resolution and sensitivity Page 20

22 2017/09/26 THANK YOU FOR YOUR ATTENTION QUESTIONS? / This project has received funding from the Europeen Union s Horizon 2020 research and innovation program under grant agreement no RAAI