wheel/rail contact oldrich polach geometry parameters
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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
310th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
410th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
510th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
610th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
Wheel/rail contact geometry A
Wheel/rail contact geometry B
Wheel/rail contact geometry A
Wheel/rail contact geometry B
710th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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]
810th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
910th 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
1010th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
1110th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
1210th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
1310th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
1410th 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
1510th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
1610th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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]
Equivalent conicity function
0 km 29,000 km 115,000 km 239,000 km
Running distance
1710th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
]
Wheelset displacement [mm]
Contact point movement
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
1810th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
]
Wheelset displacement amplitude [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
1910th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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[ -
]
Wheelset displacement [mm]
Contact concentration index
Example:Wheel profile S1002, Rail 60E1 1:40, Track gauge1435 mm
0.0
1.0
0.5
1.5
2010th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
]
Wheelset displacement [mm]
Contact point movement
0
2
4
6
8
10
12
0 1 2 3 4 5 6
dLW
[mm
/mm
]
Wheelset displacement amplitude [mm]
Contact bandwidth change rate
0
0.5
1
1.5
2
2.5
3
-5 -4 -3 -2 -1 0 1 2 3 4 5
c C[ -
]
Wheelset displacement [mm]
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
2110th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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[ -
]
Equivalent conicity [ - ]
Contact concentration index
0.25
0.40
0.45
0.30
0.50
0.35
2210th 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
2310th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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 [ - ]
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
2410th 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
2510th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
Contact concentration index
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
]
Wheelset displacement [mm]
Contact point movement
0
1
2
3
4
5
6
7
8
0 1 2 3 4 5 6
dLW
[mm
/mm
]
Wheelset displacement amplitude [mm]
Contact bandwidth change rate
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
2610th 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
2710th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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
2810th International Contact Mechanics Conference | Colorado Springs, Colorado, USA, 30 August - 3 September, 2015
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