prEN 18128-1
(Main)Railway applications - New materials - Part 1: Guideline and validation methodology
Railway applications - New materials - Part 1: Guideline and validation methodology
This document specifies a process guideline and a methodology to support the introduction of new materials and processes to meet the minimum requirements in the railway sector for all rolling stock defined in EN 17343 and onboard equipment.
This document is applicable to new materials and processes for all rolling stock and onboard equipment.
Bahnanwendungen - Neue Werkstoffe - Teil 1: Leitfaden und Validierungsmethodik
Dieses Dokument definiert einen Verfahrensleitfaden und eine Methodik zur Unterstützung der Einführung neuer Werkstoffe und Verfahren, um die Mindestanforderungen im Eisenbahnsektor für alle in EN 17343 definierten Bahnfahrzeuge und Fahrzeugausrüstungen zu erfüllen.
Dieses Dokument gilt für neue Werkstoffe und Verfahren für alle Bahnfahrzeuge und Fahrzeugausrüstungen.
Applications ferroviaires - Nouveaux matériaux - Partie 1 : Lignes directrices et méthodologie de validation
Le présent document définit des lignes directrices de processus ainsi qu'une méthodologie visant à encadrer l'introduction de nouveaux matériaux et procédés dans le but de respecter les exigences minimales du secteur ferroviaire pour tous les matériels roulants définis dans l'EN 17343 et pour les équipements embarqués.
Le présent document s'applique aux nouveaux matériaux et procédés pour tous les matériels roulants et pour les équipements embarqués.
Železniške naprave - Novi materiali - 1.del: Smernica in metodologija potrjevanja
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2025
Železniške naprave - Novi materiali - 1.del: Smernica in metodologija potrjevanja
Railway applications - New materials - Part 1: Guideline and validation methodology
Bahnanwendungen - Neue Werkstoffe - Teil 1: Leitfaden und Validierungsmethodik
Applications ferroviaires - Nouveaux matériaux - Partie 1 : Lignes directrices et
méthodologie de validation
Ta slovenski standard je istoveten z: prEN 18128-1
ICS:
45.040 Materiali in deli za železniško Materials and components
tehniko for railway engineering
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2024
ICS 45.040; 45.060.01
English Version
Railway applications - New materials - Part 1: Guideline
and validation methodology
Applications ferroviaires - Nouveaux matériaux - Partie Bahnanwendungen - Neue Werkstoffe - Teil 1:
1 : Lignes directrices et méthodologie de validation Leitfaden und Validierungsmethodik
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 256.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.
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, Türkiye 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 European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 18128-1:2024 E
worldwide for CEN national Members.
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Validation methodology . 7
4.1 General. 7
4.2 Concept . 8
4.2.1 General. 8
4.2.2 Specifications . 8
4.3 Requirements and prioritization . 8
4.4 Validation of requirements R . 8
X
4.5 Test and correlation . 9
4.5.1 General. 9
4.5.2 Is subset or full-scale testing required? . 9
4.5.3 Subset or full-scale testing . 9
4.5.4 Is the subset or full-scale test validated? . 9
4.5.5 Is fitting test results with calculation required? . 9
4.6 Part validated . 9
5 Safety requirements validation . 10
5.1 Static . 10
5.1.1 General. 10
5.1.2 Preliminary design . 11
5.1.3 Advanced design . 12
5.1.4 Static requirement validated . 13
5.2 Fatigue . 15
5.2.1 General. 15
5.2.2 Preliminary design . 15
5.2.3 Advanced fatigue design . 17
5.2.4 Fatigue requirement validated . 19
5.3 Crash . 21
5.3.1 General. 21
5.3.2 Preliminary design . 21
5.3.3 Advanced design . 23
5.3.4 Crash requirement validated . 24
5.4 Impact . 26
5.4.1 General. 26
5.4.2 Preliminary design . 26
5.4.3 Advanced design . 27
5.5 Assembly methods . 29
5.5.1 General. 29
5.5.2 Design process . 30
5.6 Modal analysis . 30
5.7 Fire and smoke toxicity . 31
5.8 Electromagnetic compatibility and conductivity . 31
5.9 External environment . 32
6 Manufacturing. 33
7 Maintenance . 33
Bibliography . 34
European foreword
This document (prEN 18128-1:2024) 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 CEN Enquiry.
Introduction
The purpose of this document is to specify a process guideline and a methodology to support the
introduction of new materials and processes to meet the minimum requirements in the railway sector in
a robust, efficient and safe manner whilst supporting the confidence level and acceptability during the
approval process.
This document answers to the following points:
— most existing standards for the design of railway vehicles are dedicated to standardized metallic
materials and cannot be fully applied to new materials and/or processes. In fact, some of them are
non-isotropic materials, multi-layer materials, strongly dependent on external environment, with
different behaviour regarding fatigue, impact etc.;
— new materials and/or processes offer improved performance characteristics, e.g. reduced weight,
whole life costs/reduced LCC, environmental benefits, energy efficiency, etc.
— new materials offer the opportunity for the product to be more multifunctional e.g. a structural
material incorporating insulation (acoustic, thermal, electrical, etc.);
— many existing standards are written around existing materials and may not be appropriate for or
limit the use of new materials;
— the acceptance and approval procedures can be prolonged and costly due to uncertainties / lack of
experience with new materials.
Further parts of this standard dedicated to each specific material and processes (composite materials,
additive manufacturing, new alloys etc.) will be written based on this guideline and methodology. These
new parts will include methodology to define specific criteria, safety factors, tests, controls etc. associated
with each material and processes.
1 Scope
This document defines a process guideline and a methodology to support the introduction of new
materials and processes to meet the minimum requirements in the railway sector for all rolling stock
defined in EN 17343 and onboard equipment.
This document is applicable to new materials and processes for all rolling stock and onboard equipment.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 50125-1, Railway applications — Environmental conditions for equipment — Part 1: rolling stock and
on-board equipment
EN 60721-3-5, Classification of environmental conditions — Part 3: Classification of groups of
environmental parameters and their severities — Section 5: Ground vehicle installations (IEC 60721-3-5)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
primary structural parts
parts whose main purpose is to withstand the principal loads to which the train is subjected, and that
have a direct influence on the safety of people, avoiding serious harm (High Risk)
EXAMPLES Carbody, running gear, crash elements, couplers, underframe equipment, jacking and lifting
features
3.2
secondary structural parts
parts which participate in the distribution of the principal loads to the main structure and supplement
the safety of people, avoiding serious and moderate harm (Medium Risk)
EXAMPLES Doors, seats, interior body-mounted equipment, windscreens, windows, gangways
3.3
non-structural parts
parts of the vehicle without relevance to the structure and safety of people (Low Risk)
3.4
crash
collision between a rail vehicle and a large object
Note 1 to entry: The large object could be, for example, another rail vehicle, a road vehicle, animals or fixed
infrastructure.
Note 2 to entry: Crash energy is typically measured in megajoules. See, for example EN 15227.
3.5
impact
collision between a small object and a rail vehicle, or part thereof during manufacturing, service and
maintenance
Note 1 to entry: The small object could be, for example, ballast, animal, tools or debris.
Note 2 to entry: Impact includes vandalism such as kicks, screwdriver etc.
Note 3 to entry: Impact energy is typically less than kilojoule. See, for example, EN 15152.
3.6
design
all elements that define a part or an assembly of parts
EXAMPLES Geometries, thicknesses, assemblies, surface condition, color
3.7
full-scale test
test where the specimen is made using full-scale components from the vehicle being assessed
3.8
subset test
test where the specimen is made using part of the full-scale components from the vehicle being assessed
3.9
safety requirement
requirement that is needed to ensure the safety of the product
3.10
safe life
fatigue resistance concept that does not allow any failure of the component during the goal design lifetime
3.11
fail safe
resistance concept where the component, in case of failure on the main load path, is capable to do a load
redistribution using an alternative load path
3.12
damage tolerant
this resistance concept assumes the unavoidable existence of defects in the materials
Note 1 to entry: Regarding this resistance concept, the component must maintain its full safety and functionality
for usual operational scenarios despite of the presence of defects smaller than critical size.
4 Validation methodology
4.1 General
The overall strategy to support the introduction of new materials and processes to meet the minimum
requirements in the railway sector is illustrated in Figure 1. It is a flowchart which describes the different
steps to fulfil.
4.2 Concept
4.2.1 General
The first step of the validation methodology which is called “concept” is to precisely define the
specifications of the part or the assembly of parts subjected to be manufactured with new materials
or/and processes to identify requirements that will have to be fulfilled to validate the part.
4.2.2 Specifications
The specification of designed and manufacturing part using new material corresponds to the following
points:
— trains that could be encountered. As example, category of railway vehicle. As example (L), (P), or (F)
in accordance with EN 12663-1 and C-I, C-II or C-III in accordance with EN 15227;
— location of the part in the railway vehicle: interior or exterior;
— allocated volume and Interfaces with other parts in the train;
— accessibility;
— structural classification of the part: primary, secondary, or non-structural part;
— environment of the part: exposed to impacts, humidity, temperature, cleaning chemicals,
electromagnetic field, electric current etc.;
— contract requirements such as lifetime, maintenance intervals, comfort, target price, weight, visual
aspect, geometries…. that could be subjected to change during the project.
4.3 Requirements and prioritization
Depending on the previous specifications, a list of the different requirements (R ) that shall be validated
x
is established such as static, fatigue, impact, fire and smoke etc.
For each requirement, standards to fulfil shall be identified as well as potential complements asked by
the contractors or necessary modifications depending on the material such as additional tests, load cases,
safety factors, validation criteria etc. For some materials and processes some standards cannot be fully
applied. The strategy and methods to cover the gaps are studied in the following parts.
Finally, a validation order can be established for the requirements depending on the solicitation of the
part and the material behaviours. This order is mainly determined regarding the experience of the
manufacturer. For example, since most of thermoplastics materials have poor fire resistance, the
requirement for fire and smoke toxicity should be validated in the beginning (for example R in Figure 1).
4.4 Validation of requirements R
X
In this stage, an iteration allowing the validation of all requirements is carried out on the following
parameters: design of the part including assembly methods, materials and processes.
During this iteration, if one of those parameters shall be changed to allow the validation of one
requirement, the previous requirements shall be validated again with the new parameters. When a
solution of parameters is found allowing the validation of all requirements, the next step can be carried
out.
Note: If subset or full-size tests are necessary to fully validate a requirement, they will be done in the next
step of the flowchart. Otherwise, there is a risk to carry out costly tests on a design, material or process
that do not allow to validate all other requirements, and which might be useless.
4.5 Test and correlation
4.5.1 General
This step aims, when it is required, to test a subset or the full-scale part and correlate results with
calculation.
4.5.2 Is subset or full-scale testing required?
If the manufacturer wants to be more confident on its design, or if it is mandatory by the standards or by
the contractor of the project to carry out subset or full-scale tests, they shall be done at this stage. If it is
not the case the part is validated.
4.5.3 Subset or full-scale testing
In this step, a subset or a full-scale part is manufactured with the design, materials and processes
determined previously and is tested as defined by standards or the contractor. This will allow to validate
the hypothesis taken for the calculations such as material data, manufacturing, boundary conditions,
assembly properties…. Tests will be carried out in laboratory or/and in line.
4.5.4 Is the subset or full-scale test validated?
If the subset or full-scale test is not validated according to the standard or contractor validation criteria
for one or several requirements, the cause will have to be identified such as the design, the manufacturing,
boundary conditions, the assembly properties or the testing conditions.
If the non-validation is due to the design of the part, materials or processes, they will have to be modified
and all the validation process shall be carried out again.
4.5.5 Is fitting test results with calculation required?
If it is required by standards or by the contractor, a correlation between subset or full-size test results
and numerical or analytical calculation shall be carried out at this stage. This correlation is possible if the
part is pre-equipped with sensors such as deformation gauges.
If the test results do not fit with the calculation, hypothesis such as manufacturing, boundary conditions,
assembly properties, testing conditions…. shall be reconsidered.
4.6 Part validated
At this stage, the part is validated regarding the overall specifications and requirements according to the
project of part with new materials.
Figure 1 — Validation methodology flowchart
5 Safety requirements validation
5.1 Static
5.1.1 General
Static requirement is mainly covered by associated standards listed in Table 1.
Table 1 — Static standards and associated rolling stock components
Static standards Rolling stock components
EN 12663 Carbody and equipment
EN 13749 Bogie
All listed standards cannot necessarily be fully applied to non-metallic materials. For example, Von Mises
stress criteria mentioned in these standards are only applicable to isotropic materials. It is thus necessary
to define dedicated criteria depending on the material.
Furthermore, static test methods and their validation criteria can be very different between materials
and thus shall be studied. Finally, safety factors can be added depending on the knowledge and confidence
on the material and its processing. Figure 2 describes a methodology to validate the static requirement
applicable to all materials.
5.1.2 Preliminary design
5.1.2.1 General
According to the concept defined in 4.2, this first part aims, to validate in static a rough design of the part
called “pre-design” with associated materials and processes.
5.1.2.2 Static specifications
Definitions of all elements to validate for the static requirements:
— associated standards listed in Table 1;
— associated load cases and derived load scenarios;
— other mandatory specifications of the contractor.
5.1.2.3 Couple [materials/processes - pre-design]
5.1.2.3.1 Materials and processes selection
Selection of materials and processes with:
— data from dedicated literature, standards, material suppliers etc.;
— data from in-house tests;
— experience of the designer on the material and processes.
At this stage several materials and processes can be selected to be evaluated.
5.1.2.3.2 Pre-design
This part corresponds to the definition of a first 3D or analytical representations of the rough geometries,
volumes, thicknesses, integration in the environment, etc. Different pre-designs can be defined at this
stage with a look at the manufacturability depending on the different materials and processes selected in
the previous step.
5.1.2.4 Static pre-sizing
This part corresponds to the first calculation of the stresses and strains of the pre-designs with associated
materials and processes regarding the static load cases.
5.1.2.5 Are stresses/strains values below maximum admissible values?
This step allows iterations to find one or several relevant couples of materials/processes and pre-designs
regarding static requirement. It consists in checking if the stresses and strains are below maximum
admissible values such as ultimate strength.
In addition to the maximum admissible values, safety factors shall be considered if they are mandatory
by the standards or by the contractor itself. Their values are determined according to the structural
category of the part (primary, secondary, non-structural parts), materials, processes, manufacturing
conditions, maintenance intervals etc.
When at least one couple of materials/processes and pre-design allows to reach stresses and strains
below admissible values, the next step can be carried out.
5.1.2.6 Need to be more confident on the materials and processes data?
Since for most of materials, mechanical properties strongly depend on the process, it is preferable to carry
out static elementary tests on specimens processed by the manufacturer of the part to be more confident
on the materials data used for the calculation compared to data sheets, literature, etc.
Furthermore, these tests will allow to reduce the value of the specified safety factors in accordance with
the contractor.
5.1.2.7 Static elementary testing on specimens
This part corresponds to carrying out static elementary tests on specimens manufactured with materials
and processes selected in 5.1.2.3.1. The different static elementary tests will be chosen regarding the
selected materials and processes according to the existing test standards or specific tests defined in
accordance with the contractor and the manufacturer. Specimens should be processed by the
manufacturer itself to be the most representative as possible with the manufacturing process of the final
part. Complementary tests such as physicochemical, health control etc., could be also carried out at this
stage to link mechanical test results with specimens manufacturing.
After testing, material data resulting from tests are updated for the static pre-sizing step (see 5.1.2.4).
5.1.3 Advanced design
5.1.3.1 General
From the preliminary design step defined in 5.1.2 where materials, processes and pre-designs were
validated, this second part aims to validate in static a detailed design called “advanced 3D design”
considering assembly methods.
5.1.3.2 Couple [Assembly methods – Advanced 3D design]
5.1.3.2.1 Assembly methods selection
Selection of assembly methods (bonding, bolts, rivets, etc.) with the methodology described in 5.5.
At this stage several assembly methods can be selected to be evaluated.
5.1.3.2.2 Advanced 3D design
At this stage, the pre-design defined in 5.1.2.3.2 is updated to a detailed design called “advanced 3D
design” created in a CAD software integrating assembly methods. The advanced 3D design includes
geometries, volumes, integration in the train etc. As for 5.1.2.3.2, the advanced 3D design shall be defined
by considering the manufacturability of the parts depending on the materials and processes chosen in
5.1.2.3.1.
5.1.3.3 Static calculation of the advanced 3D design model
At this stage, static criteria values of the advanced 3D design model are calculated by Finite Element or
equivalent analytics. Static criteria are chosen regarding materials such as Von Mises for isotropic
materials, Tsai Wu for composites materials etc.
5.1.3.4 Do static criteria values are below maximum admissible values?
This step allows iterations to validate by Finite Elements, analytical calculation one or several advanced
3D design with assembly methods. It consists in checking if the criteria values are below maximum
admissible values of the materials.
In addition to the criteria values, safety factors shall be considered if they are mandatory by the standards
or by the contractor itself. Their values are determined according to the structural category of the part
(primary, secondary, non-structural parts), materials, processes, manufacturing conditions, maintenance
intervals etc.
When at least one advanced 3D design with assembly methods allows to reach criteria values below
admissible values, the next step can be carried out.
If it is not the case, it is necessary to go back to the preliminary design step defined in 5.1.2 and select
new materials and processes.
5.1.3.5 Need to be more confident on the assembly methods data?
If the static assembly data used for the calculation are based on data sheets, literature, etc., it is preferable
to carry out tests on assembly specimens to be more confident on the static assembly data and be able to
reduce the value of the specified safety factors in accordance with the contractor.
5.1.3.6 Static elementary testing on assembly specimens
This part corresponds to carrying out of static elementary test on assembly specimens selected in
5.1.3.2.1 necessary for the calculation. The different static elementary tests will be chosen according to
5.5.
Complementary tests such as physicochemical, health control etc. could be also carried out at this stage
to link mechanical test results with specimens manufacturing.
After testing, assembly data resulting from tests are updated for the static calculation of the advanced 3D
design defined in 5.1.3.3.
5.1.4 Static requirement validated
At this stage, the part is validated regarding static requirement according to the project of part with new
materials.
Figure 2 — Static requirement flowchart
5.2 Fatigue
5.2.1 General
Fatigue requirement for rolling stock is mainly covered by associated standards listed in Table 2.
Table 2 — Fatigue standards and associated rolling stock components
Fatigue standards Rolling stock components
EN 12663 Carbody and equipment
EN 13749 Bogie
These listed standards cannot necessarily be fully applied to non-metallic materials. As example they
don’t cover fatigue criteria regarding to the stiffness degradation as it could be an issue to composite
materials. In addition, they don’t cover different fatigue philosophies from safe life concept for all
component types, as could be fail safe or damage tolerant concepts, currently in the state of the art of the
fatigue analysis in similar sectors.
Furthermore, the proposed analysis methodologies are only limited to methods based on
characterizations curves such as S-N, ε-N, not always easily available for novel or customizable materials
as composites. In such cases is needed to establish criteria for validate characterizations made “ad hoc”,
and, as an alternative, to include methods based on adequate safety factors as is possible to find in the
state of the art for composites.
Figure 3 describes a methodology to validate the fatigue requirement applicable to all materials.
5.2.2 Preliminary design
5.2.2.1 General
This first part aims, from a concept defined in 4.2, to validate in a pre-design of the part with associated
materials and processes, regarding to resistance on service actions (fatigue) specifications and
requirements.
5.2.2.2 Fatigue specifications
Definitions of all elements to validate for the fatigue requirements:
— associated standards listed in Table 2;
— basic use parameters: goal design lifetime, operation type, operation environment, etc.;
— associated load cases and derived load scenarios;
— preliminary resistance concept characterization (reasonable selection between safe life, fail safe or
damage tolerant resistance concepts);
— other mandatory specifications of the contractor.
5.2.2.3 Couple [materials/processes - pre-design]
5.2.2.3.1 Materials and processes selection
Selection of materials and processes based on:
— data provided by the supplier, technical codes, and/or bibliography, literature…;
— data coming from in-house tests;
— experience of the designer on the material and processes.
At this stage several materials and processes can be selected to be evaluated.
5.2.2.3.2 Pre-design
This part corresponds to the definition of the rough geometries, thicknesses, volumes, integration in the
environment etc. Special care shall be put to avoid as far possible stress concentration areas.
A first 3D or analytical representation is essential to determine if the chosen materials and processes
solution is consistent with the intended use.
5.2.2.4 Fatigue pre-sizing
This part corresponds to the evaluation of the fatigue resistance of the significant locations of the pre-
design model with associated materials and processes regarding the static load cases.
This evaluation is recommended to be done based on simplified and conservative assumption in:
— a few locations target;
— simplified and significant load scenarios;
— quick estimations for stress concentration factors;
— including estimative safety margins.
5.2.2.5 Are fatigue criteria critical values over the minimum desirable values?
This step allows iterations to find a relevant couple materials/processes and Pre-Design. It consists in
checking if the criteria critical values (fatigue threshold, critical defect size, recommendable interval
inspections) due to the significant load scenarios are over the minimum desirable values of the
components with chosen safety factors.
In addition to the criteria values, safety factors shall be considered if they are mandatory according to the
standards application or by the contractor. Their values are determined according to the structural
category of the part (primary, secondary, non-structural parts), materials, processes, manufacturing
conditions, maintenance intervals etc.
When at least one couple of materials/processes and the pre-design allows to reach the desirable values,
the next step can be undertaken.
If it is not the case, new materials or processes or predesign shall be chosen.
5.2.2.6 Need to be more confident on the materials and processes data?
Since for many materials, mechanical properties strongly depend on the process, it is preferable to carry
out fatigue elementary tests on specimens processed by the manufacturer of the part. This gives more
confidence on the materials data used for the calculation compared to data sheets, literature, etc.
As fatigue test are drastically long, they shall be done at the early stage of the project.
5.2.2.7 Fatigue elementary testing on specimens
This part corresponds to carrying out elementary test as defined in 5.2.2.6. For the selected materials and
processes, the different fatigue elementary tests will be chosen according to the existing test standards
or specific tests defined in accordance with the contractor and the manufacturer. The test specimens
should be produced by the manufacturer to be the most representative as possible with the
manufacturing process of the final part.
5.2.3 Advanced fatigue design
5.2.3.1 General
From the component preliminary design step defined in 5.2.2, this step aims to update to an advanced 3D
design with related assembly methods and do its analytical validation based on specifications and
requirements regarding to resistance on service actions (fatigue).
5.2.3.2 Couple [assembly methods – advanced 3D design]
5.2.3.2.1 General
At this stage, the preliminary design is updated to a detailed design and able to be manufactured
especially with assembly solutions.
5.2.3.2.2 Assembly methods selection
Selection of the assembly methods (bonding, bolts, rivets, etc., defined in 5.5) based on:
— data sheets provided by the supplier, technical codes and/or bibliography;
— data coming from in-house tests and ad hoc derived from the validation plan;
— experience of the designer on the assembly methods;
— pre-design evaluations.
The need for material treatments, coatings, and any other issue related to the fatigue behaviour shall be
defined in this point.
Since Assembly methods are quite sensitive to fatigue (typical source of critical areas), at this stage a “first
better option” assembly methods can be selected to be evaluated. Nevertheless, it is also recommended
to have in mind some alternative assembly method candidates (i.e. mechanical joint instead bonding), to
reduce the impact of the development in the case of selected solution could not pass the detail analysis.
5.2.3.2.3 Advanced 3D design
At this stage, the pre-design defined in 5.2.2.3.2 is updated to an advanced 3D design created in a CAD
software integrating assembly methods taking into account:
— the manufacturing process of each part;
— detailed definition of the assembly method (technology and detailed geometry) between the
different parts;
— special care to avoid stress concentration geometries.
The resulting 3D design will serve as the geometry basis for the detailed evaluations.
These first iterations aim to quickly rule out irrelevant assembly methods and advanced 3D design.
5.2.3.3 Fatigue evaluations of the advanced 3D design model
The evaluation of the fatigue resistance of all relevant locations should be done to ensure enough strength
under service load scenarios during the goal design lifetime of the component.
For this purpose, for each relevant location the critical fatigue values (fatigue threshold and critical
damage size) can comply with the required goal design lifetime and expected maintenance intervals.
This detailed evaluation shall be based on:
— all the relevant locations;
— selected resistance concept (safe life, fail safe or damage tolerance resistance concept) for each
location;
— defined and recognized methodology (or technical code);
— detailed estimations for stress concentration factors (if needed);
— adequate combination of load scenarios which be representative of normal load operation. This will
be derived to a representative load spectrum. (Analytics or MEF methods can be used for this
purpose;
— include adequate and justify safety margins;
— specific and detailed data (from supplier, specific bibliography, or tests) for properties and strength
data.
5.2.3.4 Are fatigue criteria values below desirable values?
This step allows iterations to find a relevant advanced 3D design and assembly methods. It consists in
checking if the criteria critical values (fatigue threshold and critical damage size) due to the load scenarios
comply with the minimum desirable durability and maintenance requirements.
These criteria and safety factor are chosen regarding the category of the part (primary, secondary,
general or non-structural parts), materials, processes, manufacturing conditions, maintenance intervals,
etc.
When at least one advanced 3D design with assembly methods allows to reach criteria values below
desirable values, the next step can be carried out.
If it is not the case, it is necessary to go back to the preliminary design step (see 5.2.2) and select new
materials and processes.
5.2.3.5 Need to be more confident on the assembly methods data?
If the assembly data used for the calculation are based on data sheets, literature… it is preferable to carry
out Tests on assembly specimens to be more confident on the assembly data and then reduce the value
of specified safety factors in agreement with the contractor.
If it is not the case, the maintenance and inspection intervals requirements can be collected and next step
can be carried out.
5.2.3.6 Fatigue testing on assembly specimens
This part corresponds to carrying out tests on assembly specimens as defined necessary for the
evaluation. The different elementary fatigue tests will be chosen according to 5.5.
After testing, fatigue assembly data resulting from tests are updated for the fatigue evaluations of
advanced 3D design defined in the 5.2.3.3.
5.2.4 Fatigue requirement validated
At this stage, the part is validated regarding fatigue requirement according to the project of part with new
materials.
Figure 3 — Fatigue requirement flowchart
5.3 Crash
5.3.1 General
Requirements for crashworthy design of rail vehicles are set out in EN 15227; these are intended to be
consistent with the static design requirements set out in EN 12663 and EN 13749.
It is possible to meet the requirements of EN 15227 using new materials and manufacturing processes;
however, there are particular requirements which require careful consideration; a methodology for
doing so is described in Figure 5 - Impact requirement flowchart.
For crash, the design strategy is necessarily an iterative process. The performance criteria in EN 15227
are highly dependent on vehicle mass; hence, the energy absorption requirements of individual elements
may need to be modified in order to achieve the overall collision energy management (CEM) strategy.
Once the 3D concept is proven, the detail design of the CEMS elements can proceed – with, for example,
simulation and prototype testing of each part to ensure the overall force-deflection characteristics are
met. Once each part is proven in isolation, EN 15227 requires a full 3D crash test in order to validate the
model of all the components’ interaction with each other.
Validation of the global flowchart for each part and then for the global CEMS.
5.3.2 Preliminary design
5.3.2.1 General
From the concept defined in 4.2, this first part aims 4.2 to validate the pre-design with associated
materials and processes in respect of crash performance.
5.3.2.2 Crash specifications
This part corresponds to the definitions of all elements to validate for the crash requirement:
— associated standards listed in the paragraph Table 1;
— associated load cases and derived load scenarios;
— other mandatory specifications of the contractor;
— further iterations may be necessary if, for example, the mass of the train changes significantly;
— particular requirements of EN 15227:
— integrity of the passenger compartment (survival space);
— deceleration limits;
— prevention of override;
— resi
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