Manicka Dhanasekar & Nannan Zong (QUT)

Acknowledgements: Robert Taylor (ARTC)/ Ian Marks (QR)/ Chris West (Thermit)/ David Wexler (UoW)/ Paul Boyd (CQU)/ Vladimir Luzin (ANSTO)/ Dr Thusyanthan (Cambridge, UK)/

Andy Take (Queens University, Canada)/ Thaminda Bandula Heva (PhD student)/ Chandu Rathod (PhD Student) & Hossein

Askarinejad (PhD Student)

THE CONTEXT IRJ is a gapped rail joint – the gap of which must be maintained over

its life: Similar to the Point Blades/ Switch IRJs are source of Impact: Similar to the Crossings in Turnouts IRJs suffer from Ratchetting: Similar to the Tips of Blades & Crossings High Yield Materials Trialed in Turnouts & IRJs; fundamental studies

are limited. THIS PRESENTATION WILL BRIDGE THIS GAP IN KNOWLEDGE

IRJs: Gapped Joints in Rail Assets

Safety Critical Devices Train Identification – Signalling Track Circuitry for Broken Rail Detection

Designed as per AS1085.12 Fabricated in Industry – High QA Life 7% - 35% of CWR : THE Problem Very difficult to use Technology for monitoring IRJ

performance/ onset of failure: TOO LOCALISED

On the IRJs (GIJs)

16km

IRJ IRJ

SLEEPERS

ISOLATED BLOCK

SECTIONRAILS

SHUNT

DEVICE

SHUNT

CURRENT

SENSORS

CURRENT SOURCE

VOLTAGE

SENSOR

PROCESSOR

OUTPUT

VOLTAGE

SENSOR

CURRENT SOURCE

CONTROL UNIT

Major Incidents: IRJ Failure

Union Pacific USA: 27 May 2000

3,500 people were evacuated

Total damages > $35 million

Canadian Pacific: 18 Jan 2002

300 people were injured; Total damages > $10M

PN Ore Car NSW: 01 Oct 2006

14 Wagons Written-Off

Track Damage

1 Week Traffic Disturbance

Failure Modes of IRJs

Railhead Ratchetting

Endpost Battering

Insulation Delamination

Bolt Looseness

Jointbar Cracking

Maintenance

Railhead Grinding

Weld Repair

Ballast Tamping

Joint Straightening

JOINT REPLACED

Repetitive Wheel Passage Cause Ratchetting & Gap

Closure Electrical signalling crew “chisel repair (mechanical damage)”

When damage is excessive, or joint bars break, new IRJs welded; No guideline to positioning of the gap: Suspended between sleepers? Or supported onto the sleeper?

Ballast depth?

Frequency of ballast tamping?

Rail Grinding near gap?

IRJs are positioned randomly when replaced

The ROOT CAUSE is the passage of loaded wheels: Let‟s re-visit the theory of wheel-rail contact

Field Practices: IRJ

Wheels Passing Gaps Produce Impact and Railhead

Ratchetting

Is Impact Load itself THE Problem?

Is the Wheel-Railhead Contact at the Un-Supported Gapped Edge THE Problem?

Is the rail yield strength THE problem?

Fundamental Research Questions

Dr Zong will uncover the answer…………

6 IRJs monitored Gap narrowing

Joint dipping

Time Based Observation: Over 19 Months

Gap Narrowed

Joint Dipped

Time Based Observation: Over 19 Months

Shakedown Theory

Assumes elliptic Hertzian Pressure: Not Applicable for IRJs

Theory 1.2

1.0

0.8

0.6

0.4

0.2

0.0

-0.22b

b0

-b-2b 3a

4a5a

6a7a

P/P0=1.02

x y

P/P

0

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

P/P

0

0.0

-0.20

0.5aa

1.5a2a -2b

-b0

-b-2b

y x

P/P0=1.49

Experiments: Lab

How does the railhead material respond?

Lattice Spacing Narrowed at Top in Severely Trafficked Railhead

0 5 10 15 20 25 30 35 40 45 50 55 60

-60

-55

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

Experiments: Field Instrumented IRJ in the field

General view of data recording setup

Modelling

Rapid Variation of Strain in the Plastic zone => Very Fine

Mesh

Is Impact @ Gap THE problem?

10mm

5mm

174KN 163KN

Gap size was 8.5mm in 2003 – now it is 5mm

~9% impact load cannot cause 65% life reduction

Contact impact from field test Contact impact force from FEA

Is low yield railhead steel THE problem?

Martensitic Stainless Steel (~1200MPa)

Maraging Steel (~2000MPa)

VAS (~1600MPa) – through hardened railhead?

INTERFACE with rail steel seems a problem

Idea???

IF the stress concentration moves away from the corner into the railhead, with reduced magnitude, THEN the rail end should behave like a continuous rail (in theory).

Is vertical cut of the rail THE problem?

Both 90° / 75° cuts are Just Vertical – leaving the top of railhead vulnerable

Would fillet shape do any good?

Rail curve length 40.05

1.42

x y

z

1852.86

1698.851544.831390.821236.811082.80928.78

774.77620.76466.74312.73

158.720.00

Stess (MPa)von Mises

Railhead Surface

RailendSurface

Rail Symmetric Surface

923.32

838.02762.81687.54612.23536.96461.66

386.32311.02235.77160.45

85.130.00

Stess (MPa)von Mises

x y

z

Rail Symmetric Surface

Railhead Surface

RailendSurface

Looks Like we ‘Solved’ THE problem?

0

20

40

60

80

100

120

140

160

180

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018

Co

nta

ct fo

rce

(KN

)

t (s)

New shape IRJ

Conventional IRJ

Impact force – very similar (Current &

Optimal)

The maximum Mises stress is 989MPa; ~

40% lower than the current1664MPa

The stress concentration is always away

from rail end, functioning as the

continuous rail

Is 989MPa still too much?

0

200

400

600

800

1000

1200

1400

1600

-0.01 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.11 0.12

Str

ess

(N/m

m2)

Strain

A1 B1

A2 B2

A3 B3

A4 A5

A6 A7

How does the railhead material respond? Heat affected zone

0

100

200

300

400

500

600

700

800

900

1000

0 5 10 15 20 25 30 35 40

0.2

% Y

ield

Str

en

gth

(N

/mm

2)

Depth from rail top (mm)

RailA

Is 989MPa still too much?

The testing done was uniaxial; in real case

hydrostatic stress will enhance yield 10% - 20%

Is THIS our New Generation IRJ?

This is good – we have a trouble-free „gap‟!

How to avoid broken joint bars?

Is jointbar stiffness THE problem?

Force transmission into jointbar complex

Better „structural jointbars‟ still fails

MAY BE we get rid of them?

New Generation IRJ - Prototyping

New Generation IRJ – QUESTIONS?

THANK

YOU