The Application of Long Range Ultrasonic Testing (LRUT) to Inspect Railway Tracks

7/28/2019 The Application of Long Range Ultrasonic Testing (LRUT) to Inspect Railway Tracks

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Copyright TWI Ltd 2011

Carmen Campos Castellanos

Yousef Gharaibeh

NDT Technology Group

TWI

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


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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.


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MonitoRail project overview

MONITORAIL: Long range inspection and conditionmonitoring of rails using guided waves

Partly funded by the FP7 programme (Research for thebenefit of SMEs) over two years

Project manager: Carmen Campos Castellanos -TWI Ltd

Jackweld


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Rail industry need & market potential

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

Recent advances in inspection and NDT techniqueshave drastically reduced the incidence of rail breaks.

However, a residual number of rail breaks still occurs


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Limitations of the existing NDT techniques

Limitation in terms of reliability of defect detection (e.g.internal defects)

Inspection speed

Maintenance is carried out in difficult conditions andoften at night

Inspection can be risky and dangerous operation

Can not cover the whole section of the rail (constraintsin detecting defects in the rail foot)


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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


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Limited defect sensitivity in the foot

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

Detection of defects in the rail head and web will also beinvestigated in order to provide a cost effective solution.

Possible Not

Possible

NotPossible


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Project objectives

To inspect critical areas where the probability for defects ishigh and there is limited access to carry out the conventionalNDT techniques.

To inspect long lengths of rail track from a limited number ofaccess 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.


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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


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LRUT- Ultrasonic Guided Waves

Much lower frequency than conventionalultrasonics

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 sonic

Frequency


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Conventional Vs LRUT

Weld

Metal loss

Metal loss

FlangeConventional

Transducer

Weld

Metal loss

Metal loss

FlangeTeletest

Tool

Guided Wave

100% Inspection

Localised Inspection


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Adopting Guided waves as Long Range

Ultrasonic Inspection technique


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Railway track cross sectional surface

(BS113A)

158.75mm

11.11mm

139.7mm

35.9mm

86.7mm

69.9mm

Head

Web

Foot


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Dispersion Curves (modelling results)

Y Gharaibeh, et allInvestigation of the behaviour of selected ultrasonic guided wave modes toinspect rails for long-range testing and monitoring Proceedings of the Institution of MechanicalEngineers, Part F: Journal of Rail and Rapid Transit, pp. 225: 311 (2011)


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

Sole existence ineach section inthe railway track.

Similar vibrationpatterns.

Displacement in

the entiresection suggests100% coverageof the cross

sectional surfaceof the railwaytrack.

Y Gharaibeh, et allInvestigation of the behaviour of selected ultrasonic guided wave modes toinspect rails for long-range testing and monitoring Proceedings of the Institution of MechanicalEngineers, Part F: Journal of Rail and Rapid Transit, pp. 225: 311 (2011)


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Wave mode characterisation (Dispersion

Curves in the foot)


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Wave mode (F7) characterisation

Displacement distribution across the width ofthe foot of F7 wave mode

Deformation shapeof the F7 wave mode


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Deformation shape ofthe F4 wave mode


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Deformation shape ofthe F2 wave mode


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Investigating different excitation

conditions


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Excitation of F2 scenario 1


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Experimental trials

TWI rail feature free

Birmingham University rail features: weld and clips


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TWI sample -Transducer arrangement


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Surface preparation and Sensor

attachment


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Defect addition


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Defect detection sensitivity

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

1

2

3

4

5

6

Time (us)

Amplitude(mv)

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)

Amplitude(mv)

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)

Amplitude(mv)

Time Domain Signal

DeadZone

defect 2mm

defect 4mm


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Birmingham University rail sample


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Work plan

To determine the effect in the wave modepropagation 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 todetect any significant change over time that

might indicate the presence of a defect.

This work is still in progress.


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Conclusion

The characteristics of ultrasonic guided waves in therail complex geometrical profile have been identified

A suitable wave mode with full volumetric coverage inhas been identified for each section of the rail.

F2 has been selected as the wave mode most suitable toinspect the foot

An improved excitation/reception conditions has beenproposed.

Defect detection sensitivity test have been conducted

Experimental validations of the models are in progress


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Future work

Improving of the quality of the propagated wave byusing:

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 thespecimen.

Further signal processing analysis is needed.

Investigate exisiting wave modes in the rail head withrespect to the problem definition.


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MONITORAIL acknowledgement

MONITORAIL is collaboration between the following organisations:TWI Ltd, Vermon SA, OpenPattern, Aerosoft S.p.A, Jackweld Ltd,Network Rail Infrastructure Ltd, Cereteth and Brunel University. The

Project is co-ordinated and managed by TWI Ltd. and is partly fundedby the EC under the Collaborative project programme- Research forSMEs & Research for SME Associations. Grant Agreement Number.26219.

Jackweld


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Thanks for your attention

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The Application of Long Range Ultrasonic Testing (LRUT) to Inspect Railway Tracks