Optimisation of Railway Crossings/file/Wan... · 45 A methodology of improving the dynamic crossing...
Transcript of Optimisation of Railway Crossings/file/Wan... · 45 A methodology of improving the dynamic crossing...
Optimisation of Railway Crossings
Chang Wan
2
Research problem
Research methods
Challenges and solutions
Conclusion
Outline
6% of the train delays due to turnouts in 2010, are
responsible for 55% of the total disruption time.
Impact of broken crossings is 28% of the
mentioned 55% of the disruption time.
Source from: I.Y. Shevtsov. Fracture problems of the crossings: Most common fractures in 2009-2012, presentation of workshopon defects in railway frogs, 2014, Kedichem, the Netherlands.
Some facts in Netherlands
4
Lipping-plastic deformation with cracks on the crossing nose
Head checksDamaged crossing noseSpalling
Damage at crossings
5
How to solve the problem?
6
Two approaches
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Approach I
Tune the crossing geometry
8
After grindingBefore grinding
Accelerations of nose rail (example of a single train passing at speed of 138.5 km/h)
5 10 15 200
20
40
60
80
100
120
140
Accele
ration (
g)
Wheelset No.
Vertical acceleration
Lateral acceleration
Total acceleration
5 10 15 200
20
40
60
80
100
120
140 Vertical acceleration
Lateral acceleration
Total acceleration
Wheelset No.
Acce
lera
tio
n (
g)
Impact along the crossing (collected data during 2 hour of train passages)
Effect of grinding
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Changing rail profiles
Crossing
Crossing
Wing rails
Crossing nose
Adjust crossing geometry
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Approach II
Tune the track elasticity
11
Rail pads
Elastic baseplates
Under Sleeper Pads(USP)
Adjust track elasticity
12
How ???
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Case 1
Case 2
…
Case n
Predefine n design cases
Best case optimum
Evaluate n cases
Traditional way in railway design optimisation
14
How to choose the n cases ???
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( ) 1, 1, ,jF j Mx
, 1, ,i i iA B i Nx
Minimise 0( ) min, NF x x R 0( ) min, NF x x R
Subject to
Initial design
Update design using optimisation method
Analyse design
Does the design satisfy convergence criteria? Done
Y
N
Numerical optimisation problem
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Evaluation of crossing design based on
Dynamic vehicle-turnout interaction
Crossing geometry optimisation
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Wheel-rail normal contact pressure S
Energy dissipation in the contact patch W Wear
RCF damage
0 1 2
( ) ( )min
( ) ( )
S WF w w
S W
X X
XX X
Optimise crossing geometry to reduce damages at wheel-rail interface!
Optimisation problem
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No risk of derailment
Sufficient support surface when impact occurs
Constraints of nose rail geometry
• Smooth-convex cross-sectional shape
• Monotonically increased height profile
Constraints
Track elasticity optimisation
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High frequency force on rail (P1) Accounts for damage at the wheel/rail interface
Low-frequency forces on ballast (Fbl) and sleepers (Fsl) Accounts for damage of the sleeper and ballast bed.
Reduction of dynamic forces on turnout crossing
1
10
1
minbl sl
bl slP F F
bl sl
F FPF W W W
P F F X
Optimisation problem
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Maximum displacement of rail
Maximum displacement of sleepers
Maximum deflection of rail pads
Constraints
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Challenges
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1.
Parameterisation of crossing design
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Parameterisation of crossing geometry
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701:
+2 -1
55 25x 4
3¡À1
¡ À5 43
¡À1 +
2 -16
0
+2 -1
90
14
mm
10*
I II III IV
25
¡À1
33
¡À1
min
. 4
5
min
R10
25
¡À1
33
¡À1
min
. 4
5
+1 -0.5
10 +
1 -0.5
5
+1 -0.5
3.5
10x ¡ À5 10x ¡ À5 50x ¡ À5
I II III IV
min R10
0
4:1 4:1
4:1 4:1
4:1 4:1
20* 70*
+1 -0.5
10 +
1 -0.5
5
+1 -0.5
3.54¡ À1
TP
(a)
(b)
(c)
10xα±5 10xα±5 50xα±5
25xα±5
4±1
33±1
25±1
33±1 25
±1
43±1
43±1
Step I: Choose control cross-sections
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Tuning cross-sections III, V
Fixed cross-sections I, II, IV
70
A B C
D
7014 m
m
2xa1
b1
2xa 2
b 2
A B C D
25 mm
55
4
1:
10x 10x 50x
20xαE
I II III VIV
Step I: Choose control cross-sections
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Longitudinal height profile of nose rail
Step II: Determine design parameters
0 200 400 600 800 1000 1200-15
-10
-5
0
5
10
15
fixed point
movable point
reference profile
adjusted profile
II
Hei
ght
[mm
]
I
h1
h2
Distance from TP [mm]
III
V
IV
Hei
ght w
.r.t t
he t
op o
f no
rmal
rai
l [m
m]
0
-14
TP
h1h2
e e 2e
Wing rail Nose rail
I II III V IV
3e
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Step II: Determine design parameters
Distance from nose rail centre [mm]
Hei
ght
[mm
]
0 5 10 15 20 25-4
-2
0
2
4
6
8
10
12
1:4
1:25
fixed control points
movablecontrol points
P0
P1 P2
P3
P4
P5
P
M
Transvers profile of nose rail (B-spline)
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Parameterisation of track elasticity
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3 6
1 2 3 4 5 6 7 8 9 10 11
Design parameters: elastic properties of rail pads & USP
Parameterisation of track elasticity
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Design parameters: elastic properties of rail pads & USP
3 6
1 2 3 4 5 6 7 8 9 10 11
M RF
transition part
Rail pad
USP
F M R
Parameterisation of track elasticity
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2.
Uncertainties in crossing design
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Robust Optimisation
f(X)
X
optimal: non-robust
suboptimal: robust
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3.
Balance between model accuracy and
computational cost
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Experimental investigation
MBS simulation
Rail surface
FEM simulation
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Optimum solution
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Nose rail shape
Longitudinal height profile of nose rail
0 200 400 600 800 1000 1200-15
-10
-5
0
5
10
15
Distance from TP [mm]
Heig
ht
[mm
]
ref
opt
II
III
V
IV
0 5 10 15 20 25 300
5
10
15
Distance from nose rail centre [mm]
Heig
ht
[mm
]
ref
opt
Optimum crossing geometry
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Shift of impact location
Reduction of contact pressure
2000
2500
3000
3500
4000
4500
5000
Conta
ct
pre
ssure
[M
Pa]
opt
ref
C2C1B2B1A2A1
200
300
400
500
600D
ista
nce f
rom
TP
[m
m]
opt
ref
A2 B1 B2 C1 C2A1
A1-C2 represent different vehicle-track conditions
Robust dynamic behaviour
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Softer rail pads combined with the USPs
Rail pads with different properties
Relatively less soft rail pads before and after the crossingnose than under the crossing nose
Optimum track elasticity
Reduction of dynamic forces--Compared to original design
Optimum designs
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How to implement ?
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Crossing before grinding Crossing after grinding
Grinding/welding maintenance
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source from Network Rai Engineering education video: https://www.youtube.com/watch?v=qsCoJJLhS68
Manufacturing process
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A methodology of improving the dynamic crossing performance by tuningcrossing designs is proposed, including:
• Adjusting crossing geometry
• Adjusting track elasticity
The methodology combines modern optimisation techniques and dynamic train-turnout interaction, and accounts for
• Multiple assessment criteria in design optimisation
• Uncertainties in design
• Realistic parameterisation of crossing designs
• Balance between accuracy and computational cost
Concluding remarks
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Details of the research can be found in
C. Wan. Optimisation of vehicle-track interaction at railway crossings. PhD thesis; TU Delft.
https://www.researchgate.net/publication/307977713_Optimisation_of_vehicle-track_interaction_at_railway_crossings
http://repository.tudelft.nl/islandora/object/uuid:8dac8f02-fe9e-4baa-9503-e9b3d79dd1aa?collection=research