wheel/rail contact oldrich polach geometry parameters

1

Oldrich PolachBombardier TransportationWinterthur, Switzerland

Dirk NicklischDB Netz AGMünchen, Germany

WHEEL/RAIL CONTACT GEOMETRY PARAMETERS IN REGARD TO VEHICLE BEHAVIOUR AND THEIR ALTERATION WITH WEAR

210th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015

Content

� Contact geometry parameters in regard to running dynamics

� Alteration of wheel/rail contact geometry parameters with wear

� New contact geometry parameters versus contact spreading

� Comparison with other publications

� Comparison of design wheel/rail profile combinations

� Conclusions


Motivation for extended characterisation of wheel/rail contact geometry

� The actual wheel/rail contact geometry changes due to wear of wheels and rails

� Equivalent conicity is used to characterise the contact geometry in regard to hunting and critical speed

� However, one value of equivalent conicity can represent very different contact geometries!

Ref.:[1] O. Polach: Characteristic parameters of nonlinear wheel/rail contact geometry. Vehicle System Dynamics, Suppl., 2010, vol. 48, pp. 19-36

� Does the shape of equivalent conicityfunction influence the vehicle dynamic behaviour?

� Do we need to extend the characterisation of wheel/rail contact geometry?

� Yes:A new contact geometry characterisationusing two parameters was proposed on the IAVSD Symposium in Stockholm 2009 [1]

Wheelset displacement amplitude

Equi

vale

nt c

onic

ity

Flange contact

3 mm


0

2

4

6

8

10

0 50 100 150 200 250 300 350 400

Whe

else

t am

plitu

de

[mm

]

Speed [km/h]

0

2

4

6

8

10

0 50 100 150 200 250 300 350 400

Whe

else

t am

plitu

de

[mm

]

Speed [km/h]

Bifurcation diagram: Vehicle 2 Bifurcation diagram: Vehicle 3

0

2

4

6

8

10

0 50 100 150 200 250 300 350 400

Whe

else

t am

plitu

de

[mm

]

Speed [km/h]

Bifurcation diagram: Vehicle 1

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 1 2 3 4 5 6 7 8

Con

icity

[ -

]

Wheelset amplitude [mm]

Equivalent conicity function

Wheel/rail contact geometry A

Wheel/rail contact geometry B

B

A

A AB

B

Contact geometry and vehicle behaviour at the stability limit

-8

-6

-4

-2

0

2

4

6

8

120140160180200220240260280

Speed [km/h]

y [

mm

]

-8

-6

-4

-2

0

2

4

6

8

120140160180200220240260280

Speed [km/h]

y [

mm

]

Wheel/rail contact geometry A Wheel/rail contact geometry B


0

2

4

6

8

10

0 50 100 150 200 250 300 350 400

Whe

else

t am

plitu

de

[mm

]

Speed [km/h]

0

2

4

6

8

10

0 50 100 150 200 250 300 350 400

Whe

else

t am

plitu

de

[mm

]

Speed [km/h]

Bifurcation diagram: Vehicle 2 Bifurcation diagram: Vehicle 3

0

2

4

6

8

10

0 50 100 150 200 250 300 350 400

Whe

else

t am

plitu

de

[mm

]

Speed [km/h]

Bifurcation diagram: Vehicle 1

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 1 2 3 4 5 6 7 8

Con

icity

[ -

]

Wheelset amplitude [mm]




B

A

A AB

B

Contact geometry and vehicle behaviour at the stability limit


Contact geometry and stability in simulations on track with irregularities and on ideal track geometry

02550

75100125150

175200

180 190 200 210 220 230 240 250 260 270 280Speed [km/h]

Non

dim

ensi

onal

max

. [%

]

0

25

50

75

100

125

150

175

200

180 190 200 210 220 230 240 250 260 270 280Speed [km/h]

Non

dim

ensi

onal

max

. [%

] 06B

06A

025

5075

100125

150175

200

140 160 180 200 220 240 260 280 300Speed [km/h]

Non

dim

ensi

onal

max

. [%

]

0

25

50

75

100

125

150

175

200

140 160 180 200 220 240 260 280 300Speed [km/h]

Non

dim

ensi

onal

max

. [%

] 06B

06A

Run on measured track irregularities Behaviour following a single excitation

Sum of guiding forces (UIC 518)

Acceleration, rms value (UIC 518) limit cycle ≈ safety limit

safety limitlimit cycle






Nonlinearity Parameter (NP)Characterisation of contact geometry by two parameters� Parameter 1 – Level parameter:

� Definition:○ Equivalent conicity for a wheelset

amplitude of 3 mm� Usage:

○ Assessment of contact geometry in regard to the safety relevant instability limit according to EN 14363

� Parameter 2 – Nonlinearity parameter:� Definition:

○ Slope of the equivalent conicity function� Usage:

○ Vehicle performance at the stability limit○ Sensitivity of the vehicle to the lateral

excitation by track irregularity � Definition:

224 λλ −

=NP

Level parameter

Performance parameter

Con

icity

λWheelset amplitude [mm]

1 2 3 4 5

Ref.:[1] O. Polach: Characteristic parameters of nonlinear wheel/rail contact geometry. Vehicle System Dynamics, Suppl., 2010, vol. 48, pp. 19-36

[1/mm]


Rolling radius difference function Equivalent conicity function

Con

icity

Flange contact

Wheelset displacement amplitude3

Type ANP > 0

42 [mm]

Δr

Wheelset displacement

Flange contact

Flange contact

Whe

else

t am

plitu

de

Vehicle speed

Type ANP > 0

Bifurcation diagram

Type BNP < 0

Type BNP < 0

Characterisation of wheel/rail contact geometry:Aim of the presentation

� No information about the in service values of nonlinearity parameter (NP) and its alteration due to wear of wheels and rails were presented so far

� This paper describes recent investigations on a large amount of measured wheel and rail profiles and shows the typical development of NP due to wear

� A hypothesis explaining the observed relationship in regard to the spreading of the contact between wheel and rail is presented

� A new parameter for assessing the concentration of contact points is proposed and suggestions for the usage of this parameter are presented

� The same equivalent conicity at the wheelset amplitude of 3 mm� Different contact geometries:

� Type A: NP > 0, Type B: NP < 0


Content






� Conclusions


Evaluation of wheel profile measurements of the German high speed trains ICE 3� Wheel profile measurements on high

speed trains ICE 3 conducted in 2003

� In total 9,030 measured wheelsets

� Calculation of equivalent conicity:

� Measured wheel profiles

� Rail 60E1 (formerly UIC 60), inclination 1:40 (at that time the nominal conditions on the most German lines)

� Nominal track gauge 1435 mm

Figures: www.hegenscheidt-mfd.com

http://www.hegenscheidt-mfd.com


Conicity and NP of measured wheel profiles of the German high speed trains ICE 3

� Evaluation of measured wheel profiles of fleet ICE 3 in combination with nominal rails and nominal track gauge

� Development of equivalent conicity and nonlinearity parameter (NP) with wear with increasing running distance

� The evaluation shows that the equivalent conicity increases while NP decreases with increasing running distance

0 100,000 200,000 300,000

Running distance [km]500,000400,000

NP

[1/m

m]

00.02

0.06

0.10

-0.10

0.04

0.08

-0.02-0.04

-0.06

-0.08

Con

icity

[ -]

0.10

0

0.15

0.30

0.40

0.35

0.20

0.05

0.25

non-driven wheelsetsdriven wheelsets

non-driven wheelsetsdriven wheelsets


Evaluation of wheel profile and rail profile data in the framework of research project DynoTRAIN

www.triotrain.eu

� Project DynoTRAIN:� Team: 22 partners� Duration: June 2009 – September 2013� Objectives:

○ To harmonise European and national standards on railway dynamics○ To reduce costs of authorization by an increasing use of simulations for vehicle acceptance

� Analyses of measured wheel and rail profile data in DynoTRAIN WP3:� Samples of wheel and rail profile data were provided by project partners� Wheel profiles:

○ Altogether more than 55,000 wheelset profiles○ Measured wheel profiles from

� high speed trains ICE and TGV, passenger coaches, locomotives, EMU, DMU and freight wagons� vehicles operated in Germany, Austria, France, Italy, Switzerland, UK, Hungary and Slovenia

� Rail profiles:○ Altogether more than 300,000 rail profiles○ Measured rail profiles from Germany, France, Italy, UK

� The wheel and rail profile pairs were evaluated in groups according to country and speed category

DynoTRAIN test campaign in Germany, France, Italy and Switzerland, October 2010

http://www.triotrain.eu


Relation between NP and equivalent conicity� Results from DynoTRAIN (measured wheel and rail profiles)

� High scatter, but the same trend in all categories� The trend is the same as observed in the evaluation of ICE wheel profiles on new rails� In average, NP decreases with increasing conicity


Content






� Conclusions


Hypothesis explaining the relationship between conicity and NP� The described phenomenon can be explained by an increase of contact

conformity with running distance

Wheelset displacement

Contact point movement

AWS-AWS

LW

LW

LW

Incr

ease

of c

onta

ct c

onfo

rmity

w

ith ru

nnin

g di

stan

ce

0

Heavily worn wheel profile

Worn wheel profile

New wheel profile


Analysis of wheel profile alteration with wear

� Measured wheel profiles of a German ICE 2 high speed train (nominal wheel profile S1002 with reduced flange thickness) was evaluated to confirm this hypothesis

� The wheel profile data were sampled systematically during a test of different wheel profile designs in 1998

� Measured wheel profiles are analysed in combination with nominal track parameters (track gauge 1435 mm, rail 60E1 1:40)

� The analysis confirms that wheel wear results in a change of the contact geometry from Type A to Type B with increasing running distance

-4

-2

0

2

4

-8 -6 -4 -2 0 2 4 6 8

Δr

[mm

]

Wheelset displacement [mm]

Rolling radius difference function

0

0.2

0.4

0.6

0.8

0 2 4 6 8 10

Con

icity

[ -

]

Wheelset displacement amplitude [mm]


0 km 29,000 km 115,000 km 239,000 km

Running distance


Parameters describing the contact spreadingContact point movement� Contact point movement dyC over the lateral wheelset displacement yWS

0

1

2

3

4

5

6

7

8

-5 -4 -3 -2 -1 0 1 2 3 4 5

dyC

[mm

/mm

]



ΔyC

ΔyWS

yC1 yC2

Example:Wheel profile S1002,Rail 60E1 1:40, Track gauge1435 mm

( )WS

WSCWSWSC

WS

WSCWSC y

yyyyyyyyydy

∆−∆+

=∆

∆=

)()()(

02

8

1210

4

6

1416


Parameters describing the contact spreadingContact bandwidth change rate� Contact bandwidth change rate dLW is proposed by Gan and Dai in [2]� This parameter considers a lateral wheelset movement with an amplitude AWS� The distance between the contact point location for yWS = -AWS and the contact point position for

yWS = AWS is defined as contact bandwidth LW

� Contact Bandwidth Change Rate dLW is the ratio of the contact bandwidth and the respective lateral wheelset displacement

Example:Wheel profile S1002,Rail 60E1 1:40, Track gauge1435 mm

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5dL

W [

mm

/mm

]


Contact bandwidth change rate

Ref.:[2] F. Gan, H. Dai: Impact of rail cant on the wheel-rail contact geometry relationship of worn tread. Paper 15. In: Proceedings of the Second International Conference on Railway Technology: Research, Development and Maintenance Railways 2014

( ) ( ) ( )WSCWSCWSW AyAyAL −−=

( )WS

WWSW A

LAdL2

=

AWS-AWS

LW

0


New parameters describing the contact spreadingContact Concentration and Contact Concentration Index� Contact Concentration cc

� Characterises the frequency of the contact point occurrence across the wheel profile

� Provides an indication of the wear distribution� Assumptions used:

○ Straight track; stochastic lateral wheelsetdisplacement with normal distribution with standard deviation σ (here σ = 2.5 mm selected)

○ It is assumed that the local wear of wheels and rails is related to the local frequency of contact point occurrence

� Contact concentration represents a reciprocal contact point movement dyC multiplied by the respective percentile pyWS(yWS) of the wheelset displacement occurrence

)()(

)(WSC

WSyWSWSC ydy

ypyc =

∑=

=n

i iWSC

iWSyWS

ydyyp

nCCI

1 )()(1

� Contact Concentration Index CCI� Characterises the average contact concentration properties of the respective combination of

wheel and rail profiles by one value� Is defined as an average value of the contact concentration cC(yWS) over the normal

distribution between -3σ and 3σ of the lateral wheelset displacement

0

0.5

1

1.5

2

2.5

3

-5 -4 -3 -2 -1 0 1 2 3 4 5

c C[ -

]


Contact concentration index

Example:Wheel profile S1002, Rail 60E1 1:40, Track gauge1435 mm

0.0

1.0

0.5

1.5


Alteration of contact parameters with vehicle‘s mileage� Contact point movement increases with wear

� The largest contact point movement occurring at new wheel profiles for wheelsetdisplacements between 1 and 2 mm is approximately doubled at worn wheel profiles and shifted closer to the centred wheelset position

� A contact point movement increasing with wear results in a wider spread of wear in rolling contact; this is indicated by the increase of contact bandwidth change rate with wear, particularly for small wheelset displacement amplitudes just after re-profiling

� The wider spreading of contact points at worn wheels is documented by decreasing contact concentration, particularly for small wheelset displacements close to zero

012345678

-5 -4 -3 -2 -1 0 1 2 3 4 5

dyC

[mm

/mm

]



0

2

4

6

8

10

12

0 1 2 3 4 5 6

dLW

[mm

/mm

]



0

0.5

1

1.5

2

2.5

3

-5 -4 -3 -2 -1 0 1 2 3 4 5

c C[ -

]


Contact concentration

0 km 29,000 km 115,000 km 239,000 km

Running distance

Increasing running distance

0

2

8

1210

4

6

14

16

0.0

1.0

0.5

1.5


Relationships between equivalent conicity, nonlinearity parameter (NP) and contact concentration index (CCI) � Equivalent conicity increases while NP decreases with increasing mileage� Equivalent conicity is indirectly proportional to CCI; this confirms the presented hypothesis that the

conicity increase is accompanied with wider contact spreading, i.e. lower contact concentration

0

0.1

0.2

0.3

0 50 100 150 200 250

Con

icity

[ -

]

Running distance [tausends km]

Equivalent conicity

-0.04

-0.02

0

0.02

0.04

0 50 100 150 200 250

NP

[1/

mm

]

Running distance [tausends km]

Nonlinearity parameter

-0.04

-0.02

0

0.02

0.04

0.1 0.15 0.2 0.25 0.3

NP

[1/

mm

]

Equivalent conicity [ - ]

Nonlinearity parameter

0.5

0.6

0.7

0.8

0.9

1

0.1 0.15 0.2 0.25 0.3

CC

I[ -

]



0.25

0.40

0.45

0.30

0.50

0.35


Content






� Conclusions


Results from other authors� High speed vehicles in China with wheels turned to design profile LMA [3]� Alteration of equivalent conicity and NP with mileage shows the same tendency as on ICE high speed

trains in Germany

-0.1

-0.05

0

0.05

0 0.1 0.2 0.3 0.4

NP

[1/m

m ]


Equivalent conicity function Nonlinearity parameter

Contact bandwidth

Running distance [km] Running distance [km]

Con

tact

poi

nt c

oord

inat

e [m

m]

Con

icity

[ -

]

Wheelset displacement amplitude [mm] Equivalent conicity [mm]

Left wheel Right wheel

Ref.:[3] Feng Gan, Huan Yun Dai, Hao Gao: Wheel-rail contact relationship of worn LMA tread calculation. Poster 42.7, IAVSD Symposium, Qingdao, August 19-23, 2013


Content






� Conclusions


Comparison of contact geometry and contact spreading parameters of selected design profiles

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5

CC

I [ -

]

Wheel/rail combination


1) Wheel EN 13715 - S1002 / h28 / e32.5 / 6.7%, Rail 60E1 1:402) Wheel P8 BR, Rail BS 113A 1:203) Wheel EN 13715 - 1/40 / h28 / e32.5 / 15%, Rail 60E1 1:204) Wheel EN 13715 - S1002 / h28 / e32.5 / 6.7%, Rail 60E1 1:205) Wheel EN 13715 - EPS / h28 / e32.5 / 10%, Rail 60E1 1:40

0

0.5

1

1.5

2

2.5

3

3.5

4

-5 -4 -3 -2 -1 0 1 2 3 4 5

dyC

[mm

/mm

]



0

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6

dLW

[mm

/mm

]



1) Wheel profile S1002, rail 60E1 1:40� Wheel profile S1002 was proposed as wear adapted profile by the expert committee ORE S1002 in 1973� It is very close to the wear adapted profile evaluated in Germany with rail inclination 1:40

2) Wheel profile P8 BR, rail BS 113A 1:20� Wheel profile introduced in UK, developed based on experience with vehicles in UK in service on tracks with

rail inclination 1:203) Wheel profile EN 13715 - 1/40, rail 60E1 1:20

� Conical wheel profile with tread inclination 1:404) Wheel profile S1002, rail 60E1 1:205) Wheel profile EN 13715 – EPS/h28/e32.5/10%, rail 60E1 1:40

� Wheel profile with the tread shape identical to P8 BR but flange thickness of 32.5 mm

0

1

4

6

5

2

3

7

8

0.00

0.50

0.75

0.25

1.00


Content






� Conclusions


Conclusions� Nonlinearity Parameter (NP) extends the characterisation of wheel/rail contact

geometry using the equivalent conicity for a wheelset displacement amplitude of 3 mm by an auxiliary information related to the dynamic vehicle behaviour

� This parameter can be applied for� assessment of profile measurements with the aim to improve the characterisation of wheel/rail

contact geometry in regard to the dynamic vehicle behaviour� use of profile combinations in simulations to allow better selection of wheel and rail profiles

intended to be used as representative contact geometries� design of new wheel profiles because it provides an indication of profile shape stability: profile

combinations with negative NP can be expected to keep their form longer than those with positive NP

� Starting with a new wheel profile, the equivalent conicity usually at first increases while NP decreases with increasing mileage

� The increase of equivalent conicity is provided by increasing conformity and larger contact spreading; therefore, the wheel profile shape gets more form stable at high mileage

� A new parameter called Contact Concentration Index (CCI) is proposed to assess the contact conformity

� CCI as well as the recently proposed Contact Bandwidth Change Rate were evaluated on samples of measured wheel profiles as well as on selected combinations of design wheel and rail profiles

� Both parameters are related to the development of the equivalent conicity due to wear; the profile combinations with high Contact Bandwidth Change Rates and small CCI will be more form stable, i.e. the tread part of the wheel profile will keep its shape

wheel/rail contact oldrich polach geometry parameters

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