influence of locomotive tractive effort on the forces between wheel and rail · ·...

OP / BWED22 Aug., 2000 - Seite -1-VortrICTAM-2.ppt

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Influence of Locomotive Tractive Efforton the Forces between Wheel and RailInfluence of Locomotive Tractive Efforton the Forces between Wheel and Rail

Oldrich POLACH

AdtranzDaimlerChrysler Rail Systems (Switzerland) Ltd

Winterthur, Switzerland



Contents

� Calculation of wheel-rail forces in railway vehicle dynamics

� Differences in the calculation of wheel-rail forces in vehicledynamics and in drive dynamics

� Model of wheel-rail forces suitable for computer simulation ofvehicle and drive dynamics interaction

� Influence of tractive effort on the wheel-rail forces during curving

� Co-simulation of vehicle dynamics and traction control

� Conclusions



� Wheel-rail forces are functions of at least four independentvariables (multi-dimensional problem):

Fx, Fy = f (sx, sy, �, a/b, Q, f)

� Wheel-rail forces are functions of at least four independentvariables (multi-dimensional problem):

Fx, Fy = f (sx, sy, �, a/b, Q, f)form of the

contact areacreepages

Calculation of Forces Between Wheel and Railin Vehicle Dynamics

� The calculation is repeated many times for each wheel in eachintegration step

� the calculation time is very important



A Time Saving Methodof Wheel-Rail Forces Calculation

� Compromise between calculation time andnecessary accuracy

� Spin taken into account

� Calculation time comparable withsaturation functions or look-up tables

� Pre-calculation superfluous

� Accuracy comparable with FASTSIM orlook-up tables

� Principle and computer code published atthe 16th IAVSD Symposium, Pretoria 1999

normalstress �

tangentialstress �

area ofadhesion

area ofslip

x

�, �

x

y

a

b

directionof motion



Comparison of Simulation and MeasurementADAMS/Rail Model of Locomotive SBB 460

� 51 rigid bodies� 84 bushings� 4 bump-stops� 24 dampers

Vehicle Model:

Coupling shaft

Wheelset

Axle box

Linkage

Mechanismof Wheelset Coupling:

Mechanismof Wheelset Coupling:



-20

0

20

40

60

Wheelset

Y rig

ht

[kN

]

-60

-40

-20

0

20

Wheelset

Y le

ft

[kN

]

FASTSIMproposedmeasurement

1 2 43

alat = 1.1 m/s²

-20

0

20

40

60

Wheelset

Y rig

ht

[kN

]

-60

-40

-20

0

20

Wheelset

Y le

ft

[kN

]


1 2 43

Lateral wheel-rail forcealat = - 0.3 m/s² R = 300 m

Comparison of Simulation and MeasurementResults

-0.6

-0.4

-0.2

0

0.2

Wheelset

Y/Q

left

[

- ]


1 2 43

-0.2

0

0.2

0.4

0.6

Wheelset

Y/Q

right

[

- ]

-0.6

-0.4

-0.2

0

0.2

Wheelset

Y/Q

left

[

- ]


1 2 43

-0.2

0

0.2

0.4

0.6

Wheelset

Y/Q

right

[

- ]

Derailment quotientalat = 1.1 m/s²alat = - 0.3 m/s²

prop

osed

FAST

SIM

Calculationtime

prop

osed

FAST

SIM

Calculationtime

prop

osed

FAST

SIM

Calculationtime



Differences of Creep-Force Functionsin Vehicle Dynamics and Drive Dynamics

� Possible for use in vehicledynamics (small creep)

� Used for longitudinal and lateraldirections

� Function of creep

� Necessary for drive dynamics (largecreep - slip)

� Usually used only for longitudinaldirection

� Function of slip velocity

Slip velocity

Cre

ep fo

rce

dry

wet

Drive Dynamics

Creep

Cre

ep fo

rce

dry

wet

Vehicle Dynamics



Creep

Adh

esio

n co

effic

ient

Slip velocity

Fric

tion

coef

ficie

nt

� Friction coefficientdecreasing with slip velocity

Wheel-Rail Model for Computer Simulationof Vehicle and Drive Dynamics

� Reduction of Kalker‘s factor

+Creep

Adh

esio

n co

effic

ient

Kalker'sfactor = 1

Kalker'sfactor < 1



0

0.1

0.2

0.3

0.4

0 10 20 30 40 50

sx [%]

�x

Calculation

water+sand

water

soap solution


� Modelling of measured creep-force functions(Measurement on locomotive SBB 460)

0

0.1

0.2

0.3

0.4

0 5 10 15 20 25 30 35 40Creep [%]

Adh

esio

n co

effic

ient

Calculation

V = 40 km/h, wetAverage curve of 7 measurements

0

0.1

0.2

0.3

0.4

0 10 20 30 40 50

sx [%]

�x

Measurement

water+sand

water

soap solution

V = 20 km/h




� Influence of vehicle speed

0

0.1

0.2

0.3

0.4

0 5 10 15 20 25Creep [%]

Adh

esio

n co

effic

ient

V = 10 km/h

0

0.1

0.2

0.3

0.4

0 5 10 15 20 25Creep [%]

Adh

esio

n co

effic

ient

V = 40 km/h

0

0.1

0.2

0.3

0.4

0 5 10 15 20 25Creep [%]

Adh

esio

n co

effic

ient

V = 70 km/h

0

0.1

0.2

0.3

0.4

0 5 10 15 20 25Creep [%]

Adh

esio

n co

effic

ient

V = 90 km/h0 3 6

9 1215

1040

70

100

00.04

0.08

0.12

0.16

0.2

0.24

0.28

0.32

0.36

�x [-]

sx [%]

v [km/h]



Simulation of Vehicle and Drive DynamicsModel of Loco SBB 460 Including Drive System

Vehicle Model:

294 Degrees of Freedom

Drive System:Drive System:

Motor

Pinion

Idler

Wheelset

Hollowshaft

Large gearwheel



Influence of Locomotive Tractive Efforton the Wheel-Rail Forces in a Curve

0 2 4 6 8�� [mrad]

Steering angle

�

R = 300 m, alat = 1 m/s²wet condition, friction coefficient

function of slip velocity

Forces between wheel and rail

-10

0

10

20

30

40

Y 2r

[

kN]

-10

0

10

20

30

40Y

1r

[kN

]

-20 -10 0 10 20 30

X 1r [kN]

-20 -10 0 10 20 30

X 1l [kN]

-50

-40

-30

-20

-10

0

Y 1l

[

kN]

-50

-40

-30

-20

-10

0

Y 2l

[

kN] -20 -10 0 10 20 30

X 2l [kN]

-20 -10 0 10 20 30

X 2r [kN]

Z = 0 kN

Z = 100 kN

Z = 200 kN

Tractive force:

-10

0

10

20

30

40

Y 2r

[

kN]

-10

0

10

20

30

40Y

1r

[kN

]

-20 -10 0 10 20 30

X 1r [kN]

-20 -10 0 10 20 30

X 1l [kN]

-50

-40

-30

-20

-10

0

Y 1l

[

kN]

-50

-40

-30

-20

-10

0

Y 2l

[

kN] -20 -10 0 10 20 30

X 2l [kN]

-20 -10 0 10 20 30

X 2r [kN]

-10

0

10

20

30

40

Y 2r

[

kN]

-10

0

10

20

30

40Y

1r

[kN

]

-20 -10 0 10 20 30

X 1r [kN]

-20 -10 0 10 20 30

X 1l [kN]

-50

-40

-30

-20

-10

0

Y 1l

[

kN]

-50

-40

-30

-20

-10

0

Y 2l

[

kN] -20 -10 0 10 20 30

X 2l [kN]

-20 -10 0 10 20 30

X 2r [kN]

0 2 4 6 8�� [mrad]

0 2 4 6 8�� [mrad]



Adhesion Tests with Locomotive SBB 460

� Test composition



Lateral displacement of wheelset relative to track

-4

-20

24

6

0 5 10 15 20

time [s]

y [

mm

]

Wheelset 1

Wheelset 2

Steering angle between the wheelsets

-1

0

1

2

3

0 5 10 15 20

time [s]

�

[mra

d]

Longitudinal force in steering linkages

-20

0

20

40

60

0 5 10 15 20

time [s]

Fx

[kN

] Wheelset 1

Wheelset 2

Rotor traction torque

-5

0

5

10

15

0 5 10 15 20

time [s]

M

[kN

m] Rotor 1

Rotor 2

Longitudinal force of wheelset 1

-10

0

10

20

30

0 5 10 15 20

time [s]

X 1 [k

N]

Ws 1 left

Ws 1 right


-10

0

10

20

30

0 5 10 15 20

time [s]

X 2 [k

N] Ws 2 left

Ws 2 right

Curve: R = 400 mCurve: R = 400 m Rail conditions: wetRail conditions: wetVehicle speed: V = 70 km/hVehicle speed: V = 70 km/h

Simulation of the Adhesion Test

� Time plots of the values on the leading bogie



Co-Simulation of Vehicle Dynamicsand Traction Control

� Mechanics(ADAMS/Rail)

� Adhesion Controller(MATLAB-SIMULINK)



� Mechanics(ADAMS/Rail)

� Adhesion Controller(MATLAB-SIMULINK)

nRs2

nRs1

Msoll

MR1

MR2

Co-Simulation of Vehicle Dynamicsand Traction Control

TractionMotorControl

TractionMotor

Speed FilterGradient

Computation

GradientController

SpeedController

SpeedSensor

Fz1

Fz2

nref

nw, opt

nx

nx,f

gw

gx nT

=3~

DSC

3~



Co-Simulation Results of the Interactionof Vehicle Dynamics and Traction Control

Vehicle speed

0

10

20

30

0 50 100 150 200 250 300

Distance along the track [m]

V [

m/s

]

Rotor torque

0

3

6

9

12

0 50 100 150 200 250 300


M1,

2

[kN

m]

Rotor 1Rotor 2


0

10

20

30

40

0 50 100 150 200 250 300


X 1 [k

N]

Ws 1 left

Ws 1 right

Traction rod force

0

10

20

30

40

0 50 100 150 200 250 300


F [

kN]

Lateral force of wheelset 1

-30

-15

0

15

30

0 50 100 150 200 250 300


Y 1 [k

N]

Ws 1 left

Ws 1 right

Steering angle between the wheelsets

-5

0

5

10

0 50 100 150 200 250 300


�

[mra

d]Bogie 1Bogie 2

Rail conditions: wetRail conditions: wetTrack design: straight, curve R = 300 m, straight, curve R = 385 mTrack design: straight, curve R = 300 m, straight, curve R = 385 m



Conclusions

� The method of wheel-rail forces calculation developed by theauthor is suitable for computation of full non-linear wheel-railforces; it takes spin into account and saves calculation time

� The presented extension of the proposed method allows aparallel simulation of vehicle and drive dynamics

� The proposed method was verified by measurements and issuitable for investigations of interaction of traction dynamics,traction control and vehicle behaviour

influence of locomotive tractive effort on the forces between wheel and rail · ·...

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