The application of Long Range Ultrasonic Testing (LRUT) to ... application of Long Range... · The application of Long Range Ultrasonic Testing (LRUT) to inspect railway tracks. ...

Copyright © TWI Ltd 2011

Carmen Campos CastellanosYousef Gharaibeh

NDT Technology GroupTWI

The application of Long Range Ultrasonic Testing (LRUT) to inspect railway tracks


Contents

• MonitoRail Project overview– Rail industry need and market potential– Limitation of current inspection methods. – Project challenges

• Long range ultrasonic testing (LRUT) • The application of guided waves as an inspection

technique. – Previous work– Deformation shape of guided waves.– Investigation of different excitation conditions.– Experimental trials

• Conclusion and Future work.


MonitoRail project overview

• MONITORAIL: “Long range inspection and condition monitoring of rails using guided waves”

• Partly funded by the FP7 programme (Research for th e benefit of SMEs) over two years

• Project manager: Carmen Campos Castellanos -TWI Ltd

Jackweld


Rail industry need & market potential

Rail breaks England, Wales and Scotland (source: Ne twork rail)

• Recent advances in inspection and NDT techniques have drastically reduced the incidence of rail breaks.

• However, a residual number of rail breaks still occurs


Limitations of the existing NDT techniques

• Limitation in terms of reliability of defect detect ion (e.g. internal defects)

• Inspection speed• Maintenance is carried out in difficult conditions and

often at night• Inspection can be risky and dangerous operation• Can not cover the whole section of the rail (constr aints

in detecting defects in the rail foot)


Current inspection method

70 DegreeProbe

Coverage

37 DegreeProbe

Coverage

0 DegreeProbes

Coverage

RSU Tyre

0 Degree Probe

37 Fw Degree Probe

37 Rev Degree Probe

70 Fw G, C & F Degree Probes

70 Rev G, C & F Degree Probes


Limited defect sensitivity in the foot

• Currently there is no method to detect foot defects other than those directly beneath the web of the rail.

• Detection of defects in the rail head and web will also be investigated in order to provide a cost effective s olution.

Possible NotPossible

NotPossible


Project objectives

• To inspect critical areas where the probability for defects is high and there is limited access to carry out the c onventional NDT techniques.

• To inspect long lengths of rail track from a limite d number of access points.

• To achieve full volumetric coverage of the rail.

• To develop a cost efficient techniquefor condition monitoring.

• To extend the life of the rail throughearly repairs of rail tracks.


Project challenges

• Accessibility

• Environmental conditions:– Rain/snow– Temperature -20 to 60 Celsius degrees.

• Interface to rail engineering/ operation staff• Existing features on the rail attenuates the signal


LRUT- Ultrasonic Guided Waves

• Much lower frequency than conventional ultrasonics

• Equivalent to Lamb waves • Use a ‘wave guide’ - a regular cross section• Complex due to large number of wavemodes

0 20 Hz 20 kHz 1GHz

Infra sound Audible sound Ultrasonic Hyper sonicFrequency


Conventional Vs LRUT

Weld

Metal loss

Metal loss

FlangeConventional Transducer

Weld

Metal loss

Metal loss

FlangeTeletest® Tool

Guided Wave

100% Inspection

Localised Inspection


Adopting Guided waves as Long Range Ultrasonic Inspection technique


Railway track cross sectional surface (BS113A)

158.75mm

11.11mm

139.7mm

35.9mm

86.7mm

69.9mm

Head

Web

Foot


Dispersion Curves (modelling results)

Y Gharaibeh, et all“Investigation of the behaviour of selected ultrasonic guided wave modes to inspect rails for long-range testing and monitoring ” Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, pp. 225: 311 (2011)


Different possible wave modes for different sections in the railway track.

• Sole existence in each section in the railway track.

• Similar vibration patterns.

• Displacement in the entire section suggests 100% coverage of the cross sectional surface of the railway track.

Y Gharaibeh, et all“Investigation of the behaviour of selected ultrasonic guided wave modes to inspect rails for long-range testing and monitoring ” Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, pp. 225: 311 (2011)


Wave mode characterisation (Dispersion Curves in the foot)


Wave mode (F7) characterisation

Displacement distribution across the width of the foot of F7 wave mode

Deformation shape of the F7 wave mode










Investigating different excitation conditions


Excitation of F2 scenario 1






Experimental trials

• TWI rail – feature free

• Birmingham University rail – features: weld and clips


TWI sample -Transducer arrangement


Surface preparation and Sensor attachment


Defect addition


Defect detection sensitivity

0 300 500 1,000 1,500 2,000 2,500 3,0000

1

2

3

4

5

6

Time (us)Am

plitu

de (m

v)

Time Domain Signal

DeadZone

(a)

0 300 500 1,000 1,500 2,000 2,500 3,0000

1

2

3

4

5

6

Time (us)

Am

plitu

de (m

v)

Time Domain Signal

DeadZone

(b)

0 300 500 1,000 1,500 2,000 2,500 3,0000

1

2

3

4

5

6

Time (us)

Am

plitu

de (m

v)

Time Domain Signal

DeadZone

defect 2mm

defect 4mm


Birmingham University rail sample


Work plan

• To determine the effect in the wave mode propagation caused by common rail features such as clips and welds.

• To identify responses due to the rail features and to monitor the signal over time in order to detect any significant change over time that might indicate the presence of a defect.

• This work is still in progress.


Conclusion

• The characteristics of ultrasonic guided waves in t he rail complex geometrical profile have been identifi ed

• A suitable wave mode with full volumetric coverage in has been identified for each section of the rail.– F2 has been selected as the wave mode most suitable to

inspect the foot

• An improved excitation/reception conditions has bee n proposed.

• Defect detection sensitivity test have been conduct ed

• Experimental validations of the models are in progr ess


Future work • Improving of the quality of the propagated wave by

using:– Minimise coherent noise. – Apply phase delay.– Apply signal weighting technique. – Enhanced signal to noise ratio.

• Further experimental validations using – Railway track with feature free specimen– Railway track with clamps mounted on the

specimen. • Further signal processing analysis is needed. • Investigate exisiting wave modes in the rail head wi th

respect to the problem definition.


MONITORAIL acknowledgement

MONITORAIL is collaboration between the following organis ations:TWI Ltd, Vermon SA, OpenPattern, Aerosoft S.p.A, Jackweld L td,Network Rail Infrastructure Ltd, Cereteth and Brunel Unive rsity. TheProject is co-ordinated and managed by TWI Ltd. and is partly fundedby the EC under the Collaborative project programme- Resear ch forSMEs & Research for SME Associations. Grant Agreement Numbe r.26219.

Jackweld


Thanks for your attention

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The application of Long Range Ultrasonic Testing (LRUT) to ... application of Long Range... · The application of Long Range Ultrasonic Testing (LRUT) to inspect railway tracks. ...

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