Investigation of the risk for Rolling Contact

Fatigue on wheels of different passenger trains

Jakob Wingren, Centre of Competence for Vehicle Dynamicsprepared by

S. Stichel, H. Mohr, J. Ågren ,R. Enblom

Bombardier Transportation

SIMPACK UM 2007, Bonn

SIMPACK UM 2007, Bonn2

Background

During the last years RCF has become more common also on passenger trains which resulted in wheel damages and more frequent reprofiling and reduced the life time of the wheels.

Therefore in this study different trains have been compared regarding their risk to develop RCF on the wheels by calculating the contact conditions between wheel and rail during curving with the multibodysimulation tool SIMPACK.

The overall aim of the study is to develop criteria that indicate the risk for RCF already in the design stage of the vehicle.

SIMPACK UM 2007, Bonn3

The phenomenon of Rolling Contact fatigue

� Surface-initiated fatigue sometimes denoted as spalling

� Subsurface-initiated fatigue sometimes denoted as shelling

� Fatigue initiated at deep defects, sometimes denoted as deep shelling or shattered rims

SIMPACK UM 2007, Bonn4

Phases of surface initiated fatigue

� Crack initiation

� Crack propagation

� Crack branching towards tread surface and wheel web

� Final fracture due to single overloads

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Visual appearance of spalling

Circumferential section

Cross section

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Effect of trapped fluid on crack propagation

Ft

Crack closes at rail contact

Hydrostatic

pressure

Crack opens just before rail contact

FtFt

Crack closes at rail contactCrack closes at rail contact

Hydrostatic

pressure

Hydrostatic

pressure

Crack opens just before rail contactCrack opens just before rail contact

SIMPACK UM 2007, Bonn7

Two criteria tested

� Shakedown map and fatigue index- developed by Chalmers, Gothenburg

� RCF damage function (Tγγγγ)- developed by AEA Technology

SIMPACK UM 2007, Bonn8

Shake down map and fatigue index

ζ

πµµ

F

abk

p

kFI surf

3

2

0

−=−=

Fatigue index developed by

Chalmers (Gothenburg)

Limit line

SIMPACK UM 2007, Bonn9

RCF damage function

RCF Damage function

-15

-10

-5

0

5

10

15

0 50 100 150 200 250 300

Wear number, Ty (Nm/m)

Dam

ag

e (

Nf x

1E

-6)

Developed by AEA Technology

- four different areas

Tγγγγ = Txννννx + Tyννννy

No damage

RCF Damage increases

Cracks are worn awaydue to severe wear

Slower damage increasedue to increased wear

SIMPACK UM 2007, Bonn10

Shakedown evaluation

Vehicle 1, Shakedown map, inner wheel

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

9,0

10,0

0,0 0,1 0,2 0,3 0,4 0,5 0,6

mue

p0/k

1. R=739m

2. R=2922m

3. R=570m

4. R=736m

5. straight track

6. straight track

7. R=430m

boundary curve

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

9,0

10,0

0,0 0,1 0,2 0,3 0,4 0,5 0,6

mue

p0/k 1. R=300m

2. R=600m3. R=1000m4. R=296m5. R=761m6. R=592m7. R=800m8. R=1000m9. R=579mboundary curve

Vehicle 2, Shakedown map, inner wheel

Vehicle 3, Shakedown map, inner wheel

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

9,0

10,0

0,0 0,1 0,2 0,3 0,4 0,5 0,6

mue

1. R=739m

2. R=2922m3. R=570m

4. R=736m5. straight track

6. straight track7. R=430m

boundary curve

p0/k

Vehicles 1 and 2 suffer from RCF

Vehicle 3 does not suffer from RCF

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Evaluation with damage parameter

Vehicle 1, D and FI versus R, nominal gauge

-0,2

0

0,2

0,4

0,6

0,8

1

0 500 1000 1500 2000 2500 3000 3500

R in m

D, P8

FI, P8

D, S1002

FI, S1002

Vehicle 2, D and FI versus R, nominal gauge

-0,2

0

0,2

0,4

0,6

0,8

1

0 200 400 600 800 1000 1200

R in m

D

FI

Vehicle 3, D and FI versus R, nominal gauge

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8

0 500 1000 151500 2000 2500 3000 3500

R in m

D

FI

- Also the damage function produces

results that correlate to the real

behaviour of the wheels.

- The damage function seems to predict

too much damage for vehicle 2 or too

little damage for vehicle 1.

SIMPACK UM 2007, Bonn12

KTH wear measure

Vehicle 2, nominal gauge

-1

-0,5

0

0,5

1

1,5

0 200 400 600 800 1000 1200

R in m

D

FI

FI/KTHwr

Vehicle 1, nominal gauge

-0,2

0

0,2

0,4

0,6

0,8

1

0 500 1000 1500 2000 2500 3000 3500

R in m

D

FI

FI/KTHwr

Wear measure:FI / Wear volume

Wear model developed by

Enblom, Jendel

KTH Rail Vehicles

SIMPACK UM 2007, Bonn13

Guideline for assessment

Suggested limits for FI and D

-0,15

-0,10

-0,05

0,00

0,05

0,10

0,15

0,20

0,25

0,00 0,20 0,40 0,60 0,80 1,00

D

FI

Area 1

Area 2

Area 3

Area 1 High risk for RCFA minor portion of the operation in this area will lead to RCF damages.

Area 2 Risk for RCFA larger portion of the operation in this area will lead to RCF damages.

Area 3 Low risk for RCFA significant portion of the operation in this area may lead to RCF damages.

SIMPACK UM 2007, Bonn14

Conclusions

� Both the shakedown theory and the damage function can be used for indicative predictions using quasistatic simulations.

� It seems that the damage function is having a slightly better correlation to the experiences of RCF.

� The study indicates that the contact pressure may not be decisive for the onset of RCF considering the results for vehicle 1/S1002, i.e. high damage values and low FI. This is in line with the experiences from the UK rail study.

� The evaluation of the FI/KTHwear measure shows that it can be very sensitive to small variations in contact pressure. It is likely that this sensitivity will decrease if applying it to transient simulations with track irregularities due to average effects.

SIMPACK UM 2007, Bonn15

Further work

� Analyze more vehicles in order to improve the validation.

� Develop an evaluation method able to accumulate damage at different positions on the tread during transient simulations with track irregularities.

� Define a methodology to accumulate damage considering both the curve and gauge distribution.

� Implement braking forces in the simulations.