SIST-TP CEN/TR 17792:2022
(Main)Railway Applications - Wheel-rail contact geometry parameters - Technical report and background information about EN 15302
Railway Applications - Wheel-rail contact geometry parameters - Technical report and background information about EN 15302
This Technical Report provides background information regarding the changes from EN 15302:2008+A1:2010 to the revised version dated 2021, including the reasons for decisions and additional explanation and guidance that is not appropriate in the standard.
The range of equivalent conicity results obtained with different software tools is described. The additional wheel-rail contact parameters, rolling radii coefficient and nonlinearity parameter, are explained. More information is also provided on the different calculation methods and the updated reference profiles for the assessment. The influence of simplifications used in determination of equivalent conicity is discussed.
To provide more information on the importance of considering the complete measurement and calculation process, methods for plausibility checks, eliminating outliers and assessing the uncertainty and repeatability of measurements are included as well as assessments of the smoothing process.
Guidance is given on fields of application of the wheel-rail contact parameters, on the selection of appropriate reference profiles (choice of reference rail profile and rail inclination for assessing wheel profiles and vice versa) and on handling special cases.
As some references in EN 14363 to wheel-rail contact test conditions have caused difficulties in understanding, clarifications issued by ERA are mentioned.
Interpretation of equivalent conicity results, using tools such as conicity maps, is discussed and various approximations such as ‘quick conicity’ assessments are also described.
Information is included on possible additional wheel-rail contact parameters, not yet ready for standardisation, but where further experience is needed.
NOTE In this document the commonly used term "wheel-rail contact geometry" is used as a synonym for the more precise term "wheelset-track contact geometry".
Bahnanwendungen - Rad-Schiene-Berührgeometrieparameter - Technischer Bericht und Hintergrundinformationen zur EN 15302
Applications ferroviaires - Paramètres géométriques du contact roue-rail - Rapport technique et informations générales sur l’EN 15302:2021
Železniške naprave - Geometrijski parametri stika kolo-tirnica - Tehnično poročilo in temeljne informacije o standardu EN 15302
To tehnično poročilo vsebuje temeljne informacije v zvezi s spremembami iz standarda EN 15302:2008+A1:2010 v revidirani različici iz leta 2021, vključno z razlogi za odločitve ter dodatnim pojasnilom in smernicami, ki v standardu niso primerni.
Opisan je razpon rezultatov ekvivalentne konicitete, pridobljenih z različnimi programskimi orodji. Pojasnjeni so dodatni parametri stika kolo-tirnica, koeficient kotalnega radija in parameter nelinearnosti. Podane so tudi dodatne informacije o različnih računskih metodah in posodobljenih referenčnih profilih za ocenjevanje. Obravnavan je vpliv poenostavitev, uporabljenih pri določanju ekvivalentne konicitete.
Za zagotovitev dodatnih informacij v zvezi s tem, kako pomembno je upoštevati celoten postopek merjenja in izračuna, so vključene metode za preverjanje verodostojnosti, odpravljanje osamelcev ter ocenjevanje negotovosti in ponovljivosti meritev, vključno z ocenami postopka izravnave.
Podane so smernice o področjih uporabe parametrov stika kolo-tirnica, o izbiri ustreznih referenčnih profilov (izbira referenčnega profila tirnice in nagiba tirnice za ocenjevanje profilov koles oz. obratno) ter o obravnavi posebnih primerov.
Ker so nekateri sklici na preskusne pogoje stika kolo-tirnica v standardu EN 14363 povzročili težave pri razumevanju, so navedena pojasnila, ki jih je izdala Evropska agencija za železniški promet (ERA).
Obravnavana je interpretacija rezultatov ekvivalentne konicitete z uporabo orodij, kot so zemljevidi konicitete, opisani pa so tudi različni približki, kot so ocene »hitre konicitete«.
Vključene so informacije o morebitnih dodatnih parametrih stika kolo-tirnica, ki še niso pripravljeni za standardizacijo, vendar so v zvezi s tem potrebne dodatne izkušnje.
OPOMBA: Splošno uporabljen izraz »geometrija stika kolo-tirnica« se v tem dokumentu uporablja kot sopomenka za natančnejši izraz »geometrija stika kolesna dvojica-tirnica«.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TP CEN/TR 17792:2022
01-april-2022
Železniške naprave - Geometrijski parametri stika kolo-tirnica - Tehnično poročilo
in temeljne informacije o standardu EN 15302
Railway Applications - Wheel-rail contact geometry parameters - Technical report and
background information about EN 15302
Bahnanwendungen - Rad-Schiene-Berührgeometrieparameter - Technischer Bericht und
Hintergrundinformationen zur EN 15302
Applications ferroviaires - Paramètres géométriques du contact roue-rail - Rapport
technique et informations générales sur l’EN 15302:2021
Ta slovenski standard je istoveten z: CEN/TR 17792:2022
ICS:
45.060.01 Železniška vozila na splošno Railway rolling stock in
general
SIST-TP CEN/TR 17792:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST-TP CEN/TR 17792:2022
CEN/TR 17792
TECHNICAL REPORT
RAPPORT TECHNIQUE
February 2022
TECHNISCHER BERICHT
ICS 17.040.20; 45.060.01
English Version
Railway Applications - Wheel-rail contact geometry
parameters - Technical report and background
information about EN 15302
Applications ferroviaires - Paramètres géométriques Bahnanwendungen - Rad-Schiene-
du contact roue-rail - Rapport technique et Berührgeometrieparameter - Technischer Bericht und
informations générales sur l'EN 15302:2021 Hintergrundinformationen zur EN 15302
This Technical Report was approved by CEN on 10 January 2022. It has been drawn up by the Technical Committee CEN/TC 256.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 17792:2022 E
worldwide for CEN national Members.
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Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Overview of the most important changes made to EN 15302 . 6
4.1 List of main changes . 6
4.2 Additional wheel-rail contact geometry parameters . 6
4.2.1 Rolling radii coefficient . 6
4.2.2 Nonlinearity parameter . 6
4.3 Methods for evaluation of equivalent conicity . 7
4.4 Assessment of the smoothing process . 7
4.5 New assessment of the complete process . 8
5 Technical background to and justification of changes in the revised EN 15302 . 8
5.1 Equivalent conicity . 8
5.1.1 Review of equivalent conicity results obtained with different software tools . 8
5.1.2 Comparison with multibody system simulation results .11
5.1.3 Influence of discretisation step size of the rolling radius difference function .14
5.2 Rolling radii coefficient .15
5.2.1 Background .15
5.2.2 Current method .17
5.3 Nonlinearity parameter .20
5.4 Calculation of equivalent conicity by two-step integration .22
5.5 Calculation of equivalent conicity by direct integration of the kinematic equation of
motion .23
5.6 Calculation of equivalent conicity by harmonic linearization .23
5.7 Updated reference profiles and results based on analytical solutions .25
5.8 Revised assessment of the smoothing process .27
5.9 Example for uncertainty assessment of the complete process .27
5.10 Influence of simplifications .31
5.10.1 General .31
5.10.2 Wheelset roll movement (rotation around the longitudinal axis) .31
5.10.3 Contact elasticity of wheel and rail .36
6 Guidance for the application of the wheel-rail contact parameters given in EN 15302
.39
6.1 Fields of application – Overview .39
6.2 General guidelines .39
6.3 Selection of appropriate reference profiles for assessment of rail head profiles
and/or wheel profiles .40
6.3.1 General .40
6.3.2 British Rail Research Survey .40
6.3.3 Reference profiles in the DynoTRAIN project.40
6.3.4 Assessment of design wheel profiles and design rail profiles .42
6.4 Development of equivalent conicity of wheelsets over mileage .43
6.5 Assessment of the contact geometry of a line .45
6.5.1 Methods for determining averaged contact geometry parameters .45
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6.5.2 Assessment of a line for different wheel profiles . 46
6.6 Rolling radii coefficient and radial steering index . 48
6.7 Nonlinearity parameter . 51
6.8 Equivalent conicity in wheel-rail maintenance and interface with TSIs . 53
6.8.1 General . 53
6.8.2 Equivalent conicity that a vehicle was designed and tested for . 53
6.8.3 Equivalent conicity as parameter in wheel profile maintenance regimes . 53
6.9 Clarification of wheel-rail contact test conditions according to EN 14363 . 54
6.10 Application of Contact angle parameter and Roll angle parameter . 55
7 Alternative contact parameters not handled in the standard . 55
7.1 Difference of contact angles and gravitational stiffness . 55
7.2 Contact Concentration Index . 56
8 Approximation of equivalent conicity by simple alternative methods. 60
8.1 Background . 60
8.2 British Rail Research investigations . 60
8.2.1 Initial BRR work in 1980s. 60
8.2.2 BRR further work in 1990s . 63
8.3 Investigations on Quick conicity using DynoTRAIN data . 66
8.3.1 DynoTRAIN project data collection . 66
8.3.2 Investigations on rail data . 67
8.3.3 Investigations on wheel data . 73
8.3.4 Combined assessment – track and wheelset . 75
8.3.5 Next Steps . 75
8.4 Ongoing development of Gradient Index Profile (GIP) . 76
8.4.1 Definition of GIP . 76
8.4.2 Comparison between equivalent conicity and GIP combined . 77
9 Development and usage of the so called conicity maps . 77
10 Plausibility check of measured profiles and elimination of outliers . 79
10.1 Introduction . 79
10.2 Profile area to be covered. 79
10.3 Spacing of points on the profile . 79
10.4 Elimination of outliers . 80
11 Examples for validation of profile measuring systems . 81
11.1 General . 81
11.2 Evaluations of rail profile measuring systems . 81
11.3 Evaluations of ground-based wheel profile measuring systems . 83
12 Effect of wheel diameter differences on the running behaviour . 84
Bibliography . 85
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European foreword
This document (CEN/TR 17792:2022) has been prepared by Technical Committee CEN/TC 256 “Railway
applications”, the secretariat of which is held by DIN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
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1 Scope
This document provides background information regarding the changes from EN 15302:2008+A1:2010
to the revised version dated 2021, including the reasons for decisions and additional explanation and
guidance that is not appropriate in the standard.
The range of equivalent conicity results obtained with different software tools is described. The
additional wheel-rail contact parameters, rolling radii coefficient and nonlinearity parameter, are
explained. More information is also provided on the different calculation methods and the updated
reference profiles for the assessment. The influence of simplifications used in determination of equivalent
conicity is discussed.
To provide more information on the importance of considering the complete measurement and
calculation process, methods for plausibility checks, eliminating outliers and assessing the uncertainty
and repeatability of measurements are included as well as assessments of the smoothing process.
Guidance is given on fields of application of the wheel-rail contact parameters, on the selection of
appropriate reference profiles (choice of reference rail profile and rail inclination for assessing wheel
profiles and vice versa) and on handling special cases.
As some references in EN 14363 to wheel-rail contact test conditions have caused difficulties in
understanding, clarifications issued by ERA are mentioned.
Interpretation of equivalent conicity results, using tools such as conicity maps, is discussed and various
approximations such as ‘quick conicity’ assessments are also described.
Information is included on possible additional wheel-rail contact parameters, not yet ready for
standardization, but where further experience is needed.
NOTE In this document the commonly used term “wheel-rail contact geometry” is used as a synonym for the
more precise term “wheelset-track contact geometry”.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
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4 Overview of the most important changes made to EN 15302
4.1 List of main changes
The list below provides an overview of the main changes introduced in the revised EN 15302:
— extension of the Scope;
— introduction of new wheel-rail contact geometry parameters (rolling radii coefficient, nonlinearity
parameter);
— improvement of the description of the methods for evaluation of equivalent conicity including the
determination of the lateral peak displacements;
— introduction of additional methods for evaluation of equivalent conicity;
— improvement of the description of the reference profiles;
— introduction of the additional reference wheel profile C;
— reference results based on analytical solutions;
— hints for plausibility checking of measured wheel and rail profiles;
— revised assessment of the profile smoothing process;
— new assessment of the complete process for determination of wheel-rail contact parameters.
In this Technical Report the ideas behind the mentioned changes and a more detailed explanation are
given where necessary.
4.2 Additional wheel-rail contact geometry parameters
4.2.1 Rolling radii coefficient
In addition to the now well-established parameter “equivalent conicity”, which describes the contact
geometry in straight track and in curves with very large radii based on a simplified model of the run of
the wheelset, an additional parameter for the guiding behaviour of the wheelset in curves with small and
very small radii is defined. This parameter, the so-called rolling radii coefficient, is intended to describe
the capability of achieving a radial position of a wheelset in the curve. Details are given in 5.2 and 6.6.
4.2.2 Nonlinearity parameter
Equivalent conicity is traditionally used to assess the wheel-rail contact geometry in regard to running
stability. However, the equivalent conicity as a linearized parameter does not consider the nonlinearity
of wheel-rail contact geometry. One value of equivalent conicity is usually used to characterize the wheel-
rail contact geometry: the equivalent conicity value for a wheelset displacement amplitude of 3 mm.
However, the same value of equivalent conicity for a wheelset displacement amplitude of 3 mm can arise
from a large number of very different contact geometries, see Figure 1.
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Figure 1 — Possible equivalent conicity functions determined from a set of wheel-rail contact
geometries with the same equivalent conicity value for a wheelset displacement amplitude of
3 mm.
Simulation studies [1] and [2] demonstrated, that the vehicle’s dynamic behaviour at the stability limit
depends on the overall properties of the wheel-rail contact geometry; therefore, also on the overall shape
of the equivalent conicity function for a range of wheelset displacements inside of the clearance between
wheelset and track (i.e. before flange contact).
A second parameter called nonlinearity parameter is proposed in [2] to enhance the characterization of
the wheel-rail contact geometry. This parameter represents the slope of the conicity function between
the wheelset amplitudes of 2 mm and 4 mm. The nonlinearity parameter does not replace the equivalent
conicity as used for the characterization of wheel-rail contact geometry regarding the stability. It should
be understood as additional information complementing the equivalent conicity. While the equivalent
conicity value for a wheelset amplitude of 3 mm represents a “level parameter” for the assessment of
contact geometry regarding the instability limit according to EN 14363, the nonlinearity parameter has
to be understood as a “performance parameter”, characterizing the vehicle performance at the stability
limit as well as the sensitivity of vehicles to the lateral excitation by track irregularity. Details are given
in 5.3 and 6.7.
4.3 Methods for evaluation of equivalent conicity
The description of all evaluation methods was largely improved. All calculation steps are now explained.
In particular, the two-step integration method was clarified (see 5.4 for details), and a description of the
direct integration of the differential equation has been added (see 5.5 for details).
Moreover, it is pointed out that the linear regression and the harmonic linearization (see 5.6 for details)
are approximations, which may give good results but have to be used with care.
Harmonic linearization has been developed in the 1970s to determine linearization parameters required
for linearized calculations of railway vehicle dynamics. As the method is usually available in simulation
tools, it is also used for the determination of equivalent conicity of measured profiles of wheels and rails.
It was thus decided to include this method in the current revision of the standard EN 15302.
4.4 Assessment of the smoothing process
As in the former versions of EN 15302, the effects of profile errors originating from the profile
measurement still have to be assessed. However, the definition of the errors to be used for the assessment
is revised and updated according to the performance of current measuring systems as well as of the
increased available computation power. Further, new quality numbers for the equivalent conicity and the
rolling radii coefficient are introduced describing the ability of the tested smoothing algorithms to deal
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with measuring errors. Hence it can be checked if the smoothing process meets the requirements taking
the measuring accuracy of the used profile measuring system into account.
More details are provided in 5.8.
4.5 New assessment of the complete process
According to EN ISO 10012:2003 (Measurement management systems - Requirement for measurement
processes and measuring equipment), an effective measurement management system ensures that
measuring equipment and measurement processes are fit for their intended use and is important in
achieving product quality objectives and managing the risk of incorrect measurement results.
An important part in/of the measurement management system is the metrological confirmation including
estimation of measurement uncertainty. The commonly used method for the estimation of measurement
uncertainty is described in ISO/IEC Guide 98-3:2008 - Guide to the expression of uncertainty in
measurement (GUM: 1995). A measurement cannot be properly interpreted without knowledge of its
uncertainty.
Corresponding to these standards a new assessment method for the complete process of wheel-rail
contact parameter determination (including measurement and calculation) is introduced in EN 15302. In
5.9 of this Technical Report an example is given for the possibility of estimation of measurement
uncertainty applied to the wheel-rail contact parameters derived from measured rail profiles.
The different methods applied today for assessment of measuring uncertainty are at least as strict as the
requirements used when the current limit values for wheel-rail contact parameters were established. The
limit values already include a margin for measuring uncertainty and no additional adjustment of the
result or the limit value shall be made.
5 Technical background to and justification of changes in the revised EN 15302
5.1 Equivalent conicity
5.1.1 Review of equivalent conicity results obtained with different software tools
In the beginning of the revision of EN 15302 a benchmark comparison of currently used calculation
methods for equivalent conicity tan γ was carried out in order to check the tolerances given in the
e
Standard against the methods. The test included all combinations of the reference wheel profiles with the
reference rail profile A as defined in the EN 15302:2008+A1:2010 as well as a selected wheel-rail
combination representing the special case described in B.3 of that document (hollow worn wheel profile).
The tan γ functions have been calculated for the following methods:
e
— direct integration of the differential equation of lateral wheelset motion;
— harmonic linearization;
— two-step integration as described in EN 15302:2008+A1:2010, Annex B;
— linear regression as described in EN 15302:2008+A1:2010, Annex C;
— analytical solution (where applicable).
In some cases, the methods are applied also accounting for the elasticity in the wheel-rail contact (non-
elliptical contact patches) and/or the effect of the axle's roll angle around the axis longitudinal to the
track due to the lateral shift of the wheelset. All the tested methods are implemented in at least two
different software tools. In total the calculation results listed in Table 1 have been provided for the
benchmark.
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Table 1 — Available results for equivalent conicity
Identifier Method Roll angle Elastic contact
considered
DB Netz Direct Integration No No
ITCF (DMA) Direct Integration No No
ALSTOM Two-step Integration No No
SNCF (Klingel) Direct Integration No No
SNCF (Ann. C) Linear Regression No No
SNCF (SIMPACK) Direct Integration ? No
Siemens (integ.) Direct Integration No No
Siemens (Ann. B) Two-step Integration No No
Siemens (Ann. C) Linear Regression No No
Siemens (harmonic) Harmonic Linearization No No
Siemens (RSGEO) Harmonic Linearization Yes No
Siemens (SIMPACK integ.) Direct Integration No Yes
Siemens (SIMPACK harm.) Harmonic Linearization No Yes
DB Systemtechnik Two-step Integration No No
IIR (ETQ) Linear Regression Yes No
IIR (Vampire) Linear Regression Yes No
NR Two-step Integration No No
The calculation results of the different methods are shown in the following Figures together with the
reference results and the respective tolerances according to EN 15302:2008+A1:2010, Annex F. Figure 2
contains the results for the symmetrical cases (identical profiles and identical wheel diameters at left-
and right-hand side) whereas Figure 3 provides the graphs for the cases with a wheel diameter difference
of 2 mm and Figure 4 for the asymmetrical wheel profiles. The analytical solutions are not plotted here
because they are nearly identical to the related original reference results.
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Figure 2 — Calculation results for equivalent conicity of various calculation methods
(reference profiles in nominal condition)
Figure 3 — Calculation results for equivalent conicity of various calculation methods
(wheel diameter difference of 2 mm applied)
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a) Comparison of equivalent conicity b) Comparison of equivalent conicity
wheels A+B worn wheel
Figure 4 — Calculation results for equivalent conicity of various calculation methods
(asymmetrical wheel profiles)
Except for the wheel-rail combination representing the special case described in B.3 (right diagram in
Figure 4), the comparisons show good agreement of the different methods and also confirm that the
tolerance bands for the equivalent conicity as given in EN 15302 are practical. There are only a few
methods providing results partly outside the tolerances, mainly for large lateral wheelset amplitudes
where the contact position is at or close to the wheel flange. As the practical meaning of equivalent
conicity values for this range of lateral wheelset amplitudes is very limited (see also below) it was decided
to restrict the normative range for which a new calculation method shall be tested against the reference
results to amplitudes of 1 mm to 6 mm.
The performed investigation showed also the high importance of a unique definition of the lateral
wheelset displacement. In the beginning, for some methods the lateral wheelset displacement was
measured at the centre of gravity of the wheelset. In combination with the consideration of the roll
movement around the longitudinal axis this resulted in significant deviations of the equivalent conicity
functions. Therefore, the revised EN 15302 contains a clear statement now: “the lateral displacement of
the wheelset as used in this document is considered at the top of rail level”.
The large scatter of conicity results for the special case with the hollow worn wheel, see the right diagram
of Figure 4, showed that there is a need for more information on how to deal with such cases. Therefore,
a new Annex H has been added to EN 15302 explaining the possible existence of multiple solutions. It is
also important to understand that the negative values of equivalent conicity shown by some calculation
tools have no physical meaning.
5.1.2 Comparison with multibody system simulation results
In order to find out up to which lateral displacement the obtai
...
SLOVENSKI STANDARD
kSIST-TP FprCEN/TR 17792:2021
01-november-2021
Železniške naprave - Geometrijski parametri stika kolo-tirnica - Tehnično poročilo
in temeljne informacije o standardu EN 15302
Railway Applications - Wheel-rail contact geometry parameters - Technical report and
background information about EN 15302
Bahnanwendungen - Rad-Schiene-Berührgeometrieparameter - Technischer Bericht und
Hintergrundinformationen zur EN 15302
Applications ferroviaires - Paramètres géométriques du contact roue-rail - Rapport
technique et informations générales sur l’EN 15302:2021
Ta slovenski standard je istoveten z: FprCEN/TR 17792
ICS:
45.060.01 Železniška vozila na splošno Railway rolling stock in
general
kSIST-TP FprCEN/TR 17792:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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kSIST-TP FprCEN/TR 17792:2021
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kSIST-TP FprCEN/TR 17792:2021
FINAL DRAFT
TECHNICAL REPORT
FprCEN/TR 17792
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
September 2021
ICS
English Version
Railway Applications - Wheel-rail contact geometry
parameters - Technical report and background
information about EN 15302
Applications ferroviaires - Paramètres géométriques Bahnanwendungen - Rad-Schiene-
du contact roue-rail - Rapport technique et Berührgeometrieparameter - Technischer Bericht und
informations générales sur l'EN 15302:2021 Hintergrundinformationen zur EN 15302
This draft Technical Report is submitted to CEN members for Vote. It has been drawn up by the Technical Committee CEN/TC
256.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a Technical Report. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a Technical Report.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TR 17792:2021 E
worldwide for CEN national Members.
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FprCEN/TR 17792:2021 (E)
Contents
European foreword . 4
1 Scope . 5
2 Overview of the most important changes made to EN 15302 . 5
2.1 List of main changes . 5
2.2 Additional wheel-rail contact geometry parameters . 6
2.2.1 Rolling radii coefficient . 6
2.2.2 Nonlinearity parameter . 6
2.3 Methods for evaluation of equivalent conicity . 7
2.4 Assessment of the smoothing process . 7
2.5 New assessment of the complete process . 7
3 Technical background to and justification of changes in the revised EN 15302 . 8
3.1 Equivalent conicity . 8
3.1.1 Review of equivalent conicity results obtained with different software tools . 8
3.1.2 Comparison with multibody system simulation results .11
3.1.3 Influence of discretisation step size of the rolling radius difference function .14
3.2 Rolling radii coefficient .15
3.2.1 Background .15
3.2.2 Current method .17
3.3 Nonlinearity parameter .19
3.4 Calculation of equivalent conicity by two-step integration .21
3.5 Calculation of equivalent conicity by direct integration of the kinematic equation of
motion .22
3.6 Calculation of equivalent conicity by harmonic linearization .22
3.7 Updated reference profiles and results based on analytical solutions .24
3.8 Revised assessment of the smoothing process .26
3.9 Example for uncertainty assessment of the complete process .26
3.10 Influence of simplifications .30
3.10.1 General .30
3.10.2 Wheelset roll movement (rotation around the longitudinal axis) .30
3.10.3 Contact elasticity of wheel and rail .35
4 Guidance for the application of the wheel-rail contact parameters given in
EN 15302 .38
4.1 Fields of application – Overview .38
4.2 General guidelines .38
4.3 Selection of appropriate reference profiles for assessment of rail head profiles
and/or wheel profiles .39
4.3.1 General .39
4.3.2 British Rail Research Survey .39
4.3.3 Reference profiles in the DynoTRAIN project.39
4.3.4 Assessment of design wheel profiles and design rail profiles .41
4.4 Development of equivalent conicity of wheelsets over mileage .42
4.5 Assessment of the contact geometry of a line .43
4.5.1 Methods for determining averaged contact geometry parameters .43
4.5.2 Assessment of a line for different wheel profiles .45
4.6 Rolling radii coefficient and radial steering index .46
4.7 Nonlinearity parameter .49
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4.8 Equivalent conicity in wheel-rail maintenance and interface with TSIs . 51
4.8.1 General . 51
4.8.2 Equivalent conicity that a vehicle was designed and tested for . 51
4.8.3 Equivalent conicity as parameter in wheel profile maintenance regimes . 51
4.9 Clarification of wheel-rail contact test conditions according to EN 14363 . 52
4.10 Application of Contact angle parameter and Roll angle parameter . 53
5 Alternative contact parameters not handled in the standard . 53
5.1 Difference of contact angles and gravitational stiffness . 53
5.2 Contact Concentration Index . 54
6 Approximation of equivalent conicity by simple alternative methods. 58
6.1 Background . 58
6.2 British Rail Research investigations . 58
6.2.1 Initial BRR work in 1980s. 58
6.2.2 BRR further work in 1990s . 60
6.3 Investigations on Quick conicity using DynoTRAIN data . 63
6.3.1 DynoTRAIN project data collection . 63
6.3.2 Investigations on rail data . 64
6.3.3 Investigations on wheel data . 70
6.3.4 Combined assessment – track and wheelset . 72
6.3.5 Next Steps . 72
6.4 Ongoing development of Gradient Index Profile (GIP) . 73
6.4.1 Definition of GIP . 73
6.4.2 Comparison between equivalent conicity and GIP combined . 74
7 Development and usage of the so called conicity maps . 74
8 Plausibility check of measured profiles and elimination of outliers . 76
8.1 Introduction . 76
8.2 Profile area to be covered. 76
8.3 Spacing of points on the profile . 76
8.4 Elimination of outliers . 77
9 Examples for validation of profile measuring systems . 78
9.1 General . 78
9.2 Evaluations of rail profile measuring systems . 78
9.3 Evaluations of ground-based wheel profile measuring systems . 80
10 Effect of wheel diameter differences on the running behaviour . 81
Bibliography . 82
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European foreword
This document (FprCEN/TR 17792:2021) has been prepared by Technical Committee CEN/TC 256
“Railway applications”, the secretariat of which is held by DIN.
This document is currently submitted to the Vote on TR.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association.
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1 Scope
This document provides background information regarding the changes from EN 15302:2008+A1:2010
to the revised version dated 2021, including the reasons for decisions and additional explanation and
guidance that is not appropriate in the standard.
The range of equivalent conicity results obtained with different software tools is described. The
additional wheel-rail contact parameters, rolling radii coefficient and nonlinearity parameter, are
explained. More information is also provided on the different calculation methods and the updated
reference profiles for the assessment. The influence of simplifications used in determination of equivalent
conicity is discussed.
To provide more information on the importance of considering the complete measurement and
calculation process, methods for plausibility checks, eliminating outliers and assessing the uncertainty
and repeatability of measurements are included as well as assessments of the smoothing process.
Guidance is given on fields of application of the wheel-rail contact parameters, on the selection of
appropriate reference profiles (choice of reference rail profile and rail inclination for assessing wheel
profiles and vice versa) and on handling special cases.
As some references in EN 14363 to wheel-rail contact test conditions have caused difficulties in
understanding, clarifications issued by ERA are mentioned.
Interpretation of equivalent conicity results, using tools such as conicity maps, is discussed and various
approximations such as ‘quick conicity’ assessments are also described.
Information is included on possible additional wheel-rail contact parameters, not yet ready for
standardization, but where further experience is needed.
NOTE In this document the commonly used term “wheel-rail contact geometry” is used as a synonym for the
more precise term “wheelset-track contact geometry”.
2 Overview of the most important changes made to EN 15302
2.1 List of main changes
The list below provides an overview of the main changes introduced in the revised EN 15302:
— extension of the Scope;
— introduction of new wheel-rail contact geometry parameters (rolling radii coefficient, nonlinearity
parameter);
— improvement of the description of the methods for evaluation of equivalent conicity including the
determination of the lateral peak displacements;
— introduction of additional methods for evaluation of equivalent conicity;
— improvement of the description of the reference profiles;
— introduction of the additional reference wheel profile C;
— reference results based on analytical solutions;
— hints for plausibility checking of measured wheel and rail profiles;
— revised assessment of the profile smoothing process;
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— new assessment of the complete process for determination of wheel-rail contact parameters.
In this Technical Report the ideas behind the mentioned changes and a more detailed explanation are
given where necessary.
2.2 Additional wheel-rail contact geometry parameters
2.2.1 Rolling radii coefficient
In addition to the now well-established parameter “equivalent conicity”, which describes the contact
geometry in straight track and in curves with very large radii based on a simplified model of the run of
the wheelset, an additional parameter for the guiding behaviour of the wheelset in curves with small and
very small radii is defined. This parameter, the so-called rolling radii coefficient, is intended to describe
the capability of achieving a radial position of a wheelset in the curve. Details are given in 3.2 and 4.6.
2.2.2 Nonlinearity parameter
Equivalent conicity is traditionally used to assess the wheel-rail contact geometry in regard to running
stability. However, the equivalent conicity as a linearized parameter does not consider the nonlinearity
of wheel-rail contact geometry. One value of equivalent conicity is usually used to characterize the wheel-
rail contact geometry: the equivalent conicity value for a wheelset displacement amplitude of 3 mm.
However, the same value of equivalent conicity for a wheelset displacement amplitude of 3 mm can arise
from a large number of very different contact geometries, see Figure 1.
Figure 1 — Possible equivalent conicity functions determined from a set of wheel-rail contact
geometries with the same equivalent conicity value for a wheelset displacement amplitude of
3 mm.
Simulation studies [1] and [2] demonstrated, that the vehicle’s dynamic behaviour at the stability limit
depends on the overall properties of the wheel-rail contact geometry; therefore, also on the overall shape
of the equivalent conicity function for a range of wheelset displacements inside of the clearance between
wheelset and track (i.e. before flange contact).
A second parameter called nonlinearity parameter is proposed in [2] to enhance the characterization of
the wheel-rail contact geometry. This parameter represents the slope of the conicity function between
the wheelset amplitudes of 2 mm and 4 mm. The nonlinearity parameter does not replace the equivalent
conicity as used for the characterization of wheel-rail contact geometry regarding the stability. It should
be understood as additional information complementing the equivalent conicity. While the equivalent
conicity value for a wheelset amplitude of 3 mm represents a “level parameter” for the assessment of
contact geometry regarding the instability limit according to EN 14363, the nonlinearity parameter has
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to be understood as a “performance parameter”, characterizing the vehicle performance at the stability
limit as well as the sensitivity of vehicles to the lateral excitation by track irregularity. Details are given
in 3.3 and 4.7.
2.3 Methods for evaluation of equivalent conicity
The description of all evaluation methods was largely improved. All calculation steps are now explained.
In particular, the two-step integration method was clarified (see 3.4 for details), and a description of the
direct integration of the differential equation has been added (see 3.5 for details).
Moreover, it is pointed out that the linear regression and the harmonic linearization (see 3.6 for details)
are approximations, which may give good results but have to be used with care.
Harmonic linearization has been developed in the 1970s to determine linearization parameters required
for linearized calculations of railway vehicle dynamics. As the method is usually available in simulation
tools, it is also used for the determination of equivalent conicity of measured profiles of wheels and rails.
It was thus decided to include this method in the current revision of the standard EN 15302.
2.4 Assessment of the smoothing process
As in the former versions of EN 15302, the effects of profile errors originating from the profile
measurement still have to be assessed. However, the definition of the errors to be used for the assessment
is revised and updated according to the performance of current measuring systems as well as of the
increased available computation power. Further, new quality numbers for the equivalent conicity and the
rolling radii coefficient are introduced describing the ability of the tested smoothing algorithms to deal
with measuring errors. Hence it can be checked if the smoothing process meets the requirements taking
the measuring accuracy of the used profile measuring system into account.
More details are provided in 3.8.
2.5 New assessment of the complete process
According to EN ISO 10012:2003 (Measurement management systems - Requirement for measurement
processes and measuring equipment), an effective measurement management system ensures that
measuring equipment and measurement processes are fit for their intended use and is important in
achieving product quality objectives and managing the risk of incorrect measurement results.
An important part in/of the measurement management system is the metrological confirmation including
estimation of measurement uncertainty. The commonly used method for the estimation of measurement
uncertainty is described in ISO/IEC Guide 98-3:2008 - Guide to the expression of uncertainty in
measurement (GUM: 1995). A measurement cannot be properly interpreted without knowledge of its
uncertainty.
Corresponding to these standards a new assessment method for the complete process of wheel-rail
contact parameter determination (including measurement and calculation) is introduced in EN 15302. In
3.9 of this Technical Report an example is given for the possibility of estimation of measurement
uncertainty applied to the wheel-rail contact parameters derived from measured rail profiles.
The different methods applied today for assessment of measuring uncertainty are at least as strict as the
requirements used when the current limit values for wheel-rail contact parameters were established. The
limit values already include a margin for measuring uncertainty and no additional adjustment of the
result or the limit value shall be made.
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3 Technical background to and justification of changes in the revised EN 15302
3.1 Equivalent conicity
3.1.1 Review of equivalent conicity results obtained with different software tools
In the beginning of the revision of EN 15302 a benchmark comparison of currently used calculation
methods for equivalent conicity tan γ was carried out in order to check the tolerances given in the
e
Standard against the methods. The test included all combinations of the reference wheel profiles with the
reference rail profile A as defined in the EN 15302:2008+A1:2010 as well as a selected wheel-rail
combination representing the special case described in B.3 of that document (hollow worn wheel profile).
The tan γ functions have been calculated for the following methods:
e
— direct integration of the differential equation of lateral wheelset motion;
— harmonic linearization;
— two-step integration as described in EN 15302:2008+A1:2010, Annex B;
— linear regression as described in EN 15302:2008+A1:2010, Annex C;
— analytical solution (where applicable).
In some cases, the methods are applied also accounting for the elasticity in the wheel-rail contact (non-
elliptical contact patches) and/or the effect of the axle's roll angle around the axis longitudinal to the
track due to the lateral shift of the wheelset. All the tested methods are implemented in at least two
different software tools. In total the calculation results listed in Table 1 have been provided for the
benchmark.
Table 1 — Available results for equivalent conicity
Identifier Method Roll angle Elastic contact
considered
DB Netz Direct Integration No No
ITCF (DMA) Direct Integration No No
ALSTOM Two-step Integration No No
SNCF (Klingel) Direct Integration No No
SNCF (Ann. C) Linear Regression No No
SNCF (SIMPACK) Direct Integration ? No
Siemens (integ.) Direct Integration No No
Siemens (Ann. B) Two-step Integration No No
Siemens (Ann. C) Linear Regression No No
Siemens (harmonic) Harmonic Linearization No No
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Siemens (RSGEO) Harmonic Linearization Yes No
Siemens (SIMPACK integ.) Direct Integration No Yes
Siemens (SIMPACK harm.) Harmonic Linearization No Yes
DB Systemtechnik Two-step Integration No No
IIR (ETQ) Linear Regression Yes No
IIR (Vampire) Linear Regression Yes No
NR Two-step Integration No No
The calculation results of the different methods are shown in the following Figures together with the
reference results and the respective tolerances according to EN 15302:2008+A1:2010, Annex F. Figure 2
contains the results for the symmetrical cases (identical profiles and identical wheel diameters at left-
and right-hand side) whereas Figure 3 provides the graphs for the cases with a wheel diameter difference
of 2 mm and Figure 4 for the asymmetrical wheel profiles. The analytical solutions are not plotted here
because they are nearly identical to the related original reference results.
Figure 2 — Calculation results for equivalent conicity of various calculation methods
(reference profiles in nominal condition)
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Figure 3 — Calculation results for equivalent conicity of various calculation methods
(wheel diameter difference of 2 mm applied)
a) Comparison of equivalent conicity b) Comparison of equivalent conicity
wheels A+B worn wheel
Figure 4 — Calculation results for equivalent conicity of various calculation methods
(asymmetrical wheel profiles)
Except for the wheel-rail combination representing the special case described in B.3 (right diagram in
Figure 4), the comparisons show good agreement of the different methods and also confirm that the
tolerance bands for the equivalent conicity as given in EN 15302 are practical. There are only a few
methods providing results partly outside the tolerances, mainly for large lateral wheelset amplitudes
where the contact position is at or close to the wheel flange. As the practical meaning of equivalent
conicity values for this range of lateral wheelset amplitudes is very limited (see also below) it was decided
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to restrict the normative range for which a new calculation method shall be tested against the reference
results to amplitudes of 1 mm to 6 mm.
The performed investigation showed also the high importance of a unique definition of the lateral
wheelset displacement. In the beginning, for some methods the lateral wheelset displacement was
measured at the centre of gravity of the wheelset. In combination with the consideration of the roll
movement around the longitudinal axis this resulted in significant deviations of the equivalent conicity
functions. Therefore, the revised EN 15302 contains a clear statement now: “the lateral displacement of
the wheelset as used in this document is considered at the top of rail level”.
The large scatter of conicity results for the special case with the hollow worn wheel, see the right diagram
of Figure 4, showed that there is a need for more information on how to deal with such cases. Therefore,
a new Annex H has been added to EN 15302 explaining the possible existence of multiple solutions. It is
also important to understand that the negative values of equivalent conicity shown by some calculation
tools have no physical meaning.
3.1.2 Comparison with multibody system simulation results
In order to find out up to which lateral displacement the obtained kinematic wheelset movement
provides a physically reasonable assessment, multibody system (MBS) simulations have been performed
and the resulting wavelengths of the lateral wheelset motion have been compared with the wavelengths
of the respective kinematic wheelset trajectory. The dynamic solutions for the lateral wheelset motion
are found by means of simulations of a single vertically loaded wheelset with a soft primary suspension
moving along straight track. Starting with an initial lateral displacement the lateral wheelset trajectory is
calculated and analysed
...
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