Cone type Phased Array Design for High Speed Hollow Axle ...For hollow axle inspection typically a number conventional probes rotating through the axles drilling are applied, without

ESIS TC24 Workshop: Integrity of Railway Structures

1 License: http://creativecommons.org/licenses/by-nd/3.0/

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 e-mail: [email protected]

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.

CONE TYPE PHASED ARRAY DESIGN FOR HIGH SPEED HOLLOW AXLE INSPECTION R. Boehm1, T. Heckel1, M. Blankschän1, W. Spruch2, T. Beggerow2 1 BAM, Bundesanstalt für Materialforschung und –prüfung, Berlin, Germany 2 BTD, Büro für Technische Diagnostik, Brandenburg, Germany

2017/09/26 – PRESENTATION

CONTENT

• Task • Principle of the scanning technique • Prior developments • New array design • Conclusion

Page 2 26. Sept., 2017 Cone type Phased Array Design for High Speed Hollow Axle Inspection ESIS TC24 Workshop, Integrity of Railway Structures, Wittenberge 2017

New Array Design for Electronic Rotation Scanning

TASK

Rail axle with longitudinal bore hole and test zones


TASK

Orientation of transversal flaw in the radial – radial plane Page 4 26. Sept., 2017 Cone type Phased Array Design for High Speed Hollow Axle Inspection ESIS TC24 Workshop, Integrity of Railway Structures, Wittenberge 2017

bore hole

testregiontransversal flaw

PRINCIPLE OF THE SCANNING TECHNIQUE

Sketch of the cone shaped phased array for electronic rotation scan Page 5 26. Sept., 2017 Cone type Phased Array Design for High Speed Hollow Axle Inspection ESIS TC24 Workshop, Integrity of Railway Structures, Wittenberge 2017

Kegelarray inmitten der Bohrung Ø 65 mm

Hohlwelle Flüssigkeit

Schallbündelrotation

Schwingerelemente Hohlwelle Axle Array Elements Fluid Axle

Conical array centered in the hole Electronic rotation

Bore hole Ø 65 mm

RESULTS OF PRIOR STUDIES

First cone array shown at ECNDT 2006 and Calculated sound fields Page 6 26. Sept., 2017 Cone type Phased Array Design for High Speed Hollow Axle Inspection ESIS TC24 Workshop, Integrity of Railway Structures, Wittenberge 2017

Büro für Technische Diagnostik (BTD)

Testing zone

Calculated sound fieldsin the plane of incidence and

perpendicular thereto

Bore hole Ø = 30 mm

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

NEW DESIGN


Geometrical boundary conditions for the current task

Lower cone diameter ≥ 20 mm

Upper cone diameter ≤ 60 mm

Bore hole Ø = 65 mm

Cone angle = 2 b b depends on the angle of incidence

Element

Max. element length

SOUND FIELD SIMULATION


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

Bore hole Active elements

Position for calclation

Focal point (example)

SOUND FIELD SIMULATION, FOCUSING


Directivity of the array with 13 active elements from 108 in total

unfocusedNor

malize

damp

litude

Circumferencial angle position in °

1.0

0.8

0.6

0.4

0.2

0.0-50 -40 -30 -20 -10 0 10 20 30 40 50

Fluid

Sound beam

Axle



Directivity of the array with 13 active elements from 108 in total, focusing in circumferential direction, focus at the surface of the axle

Fluid

Sound beam

Axle

grating lobes

focussedNor

malize

damp

litude


1.0

0.8

0.6

0.4

0.2

0.0-50 -40 -30 -20 -10 0 10 20 30 40 50

-17 dB amp. -34 dB echo



Norma

lizeda

mplitu

de


1.0

0.8

0.6

0.4

0.2

0.0-50 -40 -30 -20 -10 0 10 20 30 40 50

grating lobes

Focal points at0°, 10°, 20° and 30°

Main beam

Grating lobe

1 µs

Pulses and spectra at 0° and -20° for the focal point at 0°, normalized amplitudes Amplitudes at different swivel angles in relation to the grating lobes

17 active el., bw = 1.6°13 active el., bw = 1.8°

9 active el., bw = 2.3°5 active el., bw = 3.8°

-5 -4 -3 -2 -1 0 1 2 3 4 5

Amplit

ude


1000800600400200

0

SOUND FIELD SIMULATION, NUMBER OF ELEMENTS


Directivity of single elements of an array with 17 active elements Amplitude and divergence angle bw with different numbers of active elements

Position = 1 3 5 7 9 11 13 15 17

Amplit

ude


100

80

60

40

20

0-50 -40 -30 -20 -10 0 10 20 30 40 50

1530 1170

810

450

SOUND FIELD SIMULATION, ROTATION SCAN


Rotation of the sound field by shifting the group of active elements and by focal law

1 el. shift, -3.33° Middle position

Norma

lizeda

mplitu

de


1.0

0.8

0.6

0.4

0.2

0.0-5 -4 -3 -2 -1 0 1 2 3 4 5

steering to -1.7° Middle position

Norma

lizeda

mplitu

de


1.0

0.8

0.6

0.4

0.2

0.0-5 -4 -3 -2 -1 0 1 2 3 4 5

1 el. shift, -3.33°

SOUND FIELD SIMULATION, FOCUSING II


Concave curved elements for focusing in the plane of incidence

00.10.20.30.40.50.60.70.80.9

1

6 10 14 18 22 26

Norm

alized

amplit

ude

Element length in mmunfocused focussed



Concave curved elements for focusing in the plane of incidence

00.10.20.30.40.50.60.70.80.9

1

6 10 14 18 22 26

Norm

alized

amplit

ude

Element length in mmunfocused focussed02468

101214

6 10 14 18 22 26

Beam d

iverge

nce in °

Element length in mmunfocused focussed



Cross section of the beam at the axle surface focused and unfocused angle of incidence a in °46 44 42 40 38 36 34 32 30

mm-10 -8 -6 -4 -2 0 2 4 6 8 10

Plane elements

Curved elements 5 mm ≙ 2°

5 mm ≙ 2°



Cross section of the focused beam at the axle surface

2 mm

Cut of theplane of incidence

Line perpendicuar tothe plane of incidence

-3 dB-6 dB

-12 dB

Expected echo height

NEW DESIGNED PHASED ARRAY SYSTEM



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

THANK YOU FOR YOUR ATTENTION QUESTIONS? [email protected] / www.bam.de

2017/09/26 This project has received funding from the Europeen Union‘s Horizon 2020 research and innovation program under grant agreement no 674231 RAAI

mailto:[email protected]

Documents

Cone type Phased Array Design for High Speed Hollow Axle ...For hollow axle inspection typically a number conventional probes rotating through the axles drilling are applied, without