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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
SIMPACK UM 2007, Bonn5
Visual appearance of spalling
Circumferential section
Cross section
SIMPACK UM 2007, Bonn6
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
SIMPACK UM 2007, Bonn11
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.