EN 18128-1:2026

• Abstract:

  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.

• Status: Published
• Publication Date: 28-Jul-2026
• ICS: 45.040 - Materials and components for railway engineering
• ICS: 45.060.01 - Railway rolling stock in general
• Technical Committee: CEN/TC 256 - Railway applications
• Drafting Committee: CEN/TC 256/SC 2/WG 54 - New Materials
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 29-Jul-2026
• Due Date: 21-May-2025
• Completion Date: 29-Jul-2026
• Ref Project: SIST EN 18128-1:2026 - Railway applications - New materials - Part 1: Guideline and validation methodology

Overview

EN 18128-1:2026, developed by CEN, establishes a structured guideline and validation methodology for introducing new materials and processes in the railway sector. This standard is essential for all rolling stock as defined in EN 17343 and for onboard equipment, ensuring that innovation in materials meets minimum safety and performance requirements. With the rapid evolution of material science, including composites, advanced alloys, and novel manufacturing techniques, railway applications must manage both the potential and risks associated with these technologies. EN 18128-1:2026 provides a harmonized approach for validating new solutions, reducing uncertainties and promoting their acceptance in railway projects.

Key Topics

• Process Guideline: Step-by-step procedures for evaluating and introducing new materials and processes.
• Validation Methodology: Defined sequence for conceptualization, specification, prioritization of requirements, and verification methods.
• Risk and Safety Assessment: Guidance on categorizing railway components by structural relevance (primary, secondary, non-structural) to prioritize validation efforts.
• Testing Procedures: Instructions for subset and full-scale testing, correlation with calculations, and the iterative validation of design parameters.
• Safety Requirements: Detailed approach for validating static, fatigue, crash, and impact requirements in the context of new material applications.
• Assembly and Integration: Consideration for assembly methods (e.g., bonding, fasteners) and their influence on the performance and reliability of new materials.
• Environmental and Functional Performance: Requirements for fire and smoke toxicity, electromagnetic compatibility, resistance to environmental stressors, and manufacturability.
• Iterative Approach: A looped process to revise materials, design, and processes based on test feedback and requirements outcomes.

Applications

EN 18128-1:2026 is widely applicable across the railway industry, particularly for:

• Rolling Stock Manufacturers: Adoption of lightweight composites, advanced polymers, or hybrid materials for car bodies, bogies, and equipment housings.
• Onboard Equipment Developers: Integration of new materials for interior and exterior equipment, such as seating, doors, windows, and insulation components.
• Component Suppliers: Validation of polymer, composite, and alloy components for use in safety-critical and non-structural locations.
• Maintenance Teams: Assessment of how new materials influence maintenance cycles, repairability, and lifetime costs.
• Design Engineers: Incorporation of multifunctional materials that enhance performance, reduce weight, or provide integrated features (such as acoustic and thermal insulation).
• Regulatory Bodies and Auditors: Standardization of approval procedures for innovative materials not fully addressed by legacy standards.

By following EN 18128-1:2026, stakeholders can streamline development, testing, and certification of novel materials, avoiding costly delays, reducing safety uncertainties, and accelerating the deployment of advanced solutions in railway applications.

Related Standards

Organizations implementing EN 18128-1:2026 should be aware of the following related standards:

• EN 17343: Prescribes definitions and minimum requirements for rolling stock to which EN 18128-1:2026 applies.
• EN 50125-1: Specifies environmental conditions for railway equipment on rolling stock.
• EN 60721-3-5: Classifies environmental parameters for ground vehicle installations.
• EN 12663: Outlines strength requirements for car bodies and equipment.
• EN 13749: Establishes requirements for bogie components.
• EN 15227 & EN 15152: Provide guidelines for crashworthiness and impact test approaches.
• ISO/IEC terminology databases: Ensure clarity and uniformity in technical language related to new materials and processes in railway engineering.

EN 18128-1:2026 serves as a foundation for future standardization of specific materials and processes, such as composites, additive manufacturing, and advanced alloys, ensuring compatibility, safety, and innovation within the railway industry. This standard enables compliance, fosters sustainable engineering, and aligns with evolving railway sector technologies.

SLOVENSKI STANDARD
01-september-2026
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: EN 18128-1:2026
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.

EN 18128-1
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2026
EUROPÄISCHE NORM
ICS 45.040
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 European Standard was approved by CEN on 31 May 2026.

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. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists 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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 18128-1:2026 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 . 8
4.1 General. 8
4.2 Concept . 8
4.2.1 General. 8
4.2.2 Specifications . 8
4.3 Requirements and prioritization . 9
4.4 Validation of requirements R . 9
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 . 10
4.5.4 Is the subset or full-scale test validated? . 10
4.5.5 Is fitting test results with calculation required? . 10
4.6 Part validated . 10
5 Requirements validation . 11
5.1 Static and instability . 11
5.1.1 General. 11
5.1.2 Preliminary design . 11
5.1.3 Advanced design . 12
5.1.4 Static and instability requirement validated . 13
5.2 Fatigue . 14
5.2.1 General. 14
5.2.2 Preliminary design . 15
5.2.3 Advanced fatigue design . 16
5.2.4 Fatigue requirement validated . 18
5.3 Crash . 19
5.3.1 General. 19
5.3.2 Preliminary design . 19
5.3.3 Advanced design . 21
5.3.4 Crash design requirement defined according to crash requirements . 22
5.4 Impact . 23
5.4.1 General. 23
5.4.2 Preliminary design . 23
5.4.3 Advanced design . 25
5.4.4 Impact requirement validated . 25
5.5 Assembly methods . 26
5.5.1 General. 26
5.5.2 Design process . 26
5.6 Fire, smoke and toxicity . 27
5.7 Electromagnetic compatibility and conductivity . 27
5.8 External environment . 28
6 Manufacturing. 29
7 Maintenance . 29
Annex A (informative) Modal analysis . 30
Bibliography . 31

European foreword
This document (EN 18128-1:2026) has been prepared by Technical Committee CEN/TC 256 “Railway
applications”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2027 and conflicting national standards shall
be withdrawn at the latest by January 2027.
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.
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.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: 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 the United
Kingdom.
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 addresses the following points:
— most existing standards for the design of rail 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 might not be appropriate for or
limit the use of new materials.
— the acceptance and approval procedures can be prolonged 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 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.
2 Normative references
There are no normative references in this document.
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
new materials
non-conventional materials
any material that has not been previously used in a specific railway application area or that has been
developed recently through technological advancements
EXAMPLE Composite for primary structure
3.2
new process
set of processes in manufacturing involving a flow and/or transformation of material, information,
energy, control, or any other element in a manufacturing area
EXAMPLE Additive manufacturing, pul-braiding
3.3
CEMS
collision energy management system
system composed of several discrete elements designed to meet the criteria of collision scenarios
specified in EN 15227
Note 1 to entry: The CEMS includes components such as central buffer coupler, anti-climbing elements, etc.
3.4
component manufacturer
company responsible for the manufacture of the component with the material(s) and process(es) used
3.5
FEA
finite element analysis
computerized method of idealizing a real model for the purposes of performing structural analysis
3.6
primary structural part
part whose main purpose is to withstand the principal loads to which the train is subjected, and that has
a direct influence on the safety, avoiding serious harm (high risk)
EXAMPLE Carbody, running gear, crash elements, couplers, underframe equipment, jacking and lifting
features
3.7
secondary structural part
part which participates in the distribution of the principal loads to the primary structural part and
supplement the safety of people, avoiding serious and moderate harm (medium risk)
EXAMPLE Doors, seats, interior body-mounted equipment, windscreens, windows, gangways
3.8
non-structural part
part of the vehicle without relevance to the structure and safety of people (low risk)
3.9
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.
3.10
impact
collision between a small object and a rail vehicle, or part thereof
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 1 kilojoule. See, for example, EN 15152.
3.11
design
all elements that define a part or an assembly of parts
EXAMPLE Geometries, thicknesses, assemblies, surface condition, colour
3.12
advanced 3D design
accurate 3D model with all detail to manufacture the part incorporating geometries and interfaces, which
serves as the basis for detailed mechanical analyses (such as FEA) and for experimental validation, aiming
to ensure that the part meets the necessary criteria (for static, fatigue, etc.) before the final validation
and production
3.13
full-scale test
test where the specimen is made using full-scale components from the vehicle being assessed
3.14
subset test
test where the specimen is made using part of the full-scale components from the vehicle being assessed
3.15
safe life
fatigue resistance concept that does not allow any failure of the component during the goal design lifetime
3.16
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
3.17
damage tolerance
resistance concept that assumes the unavoidable existence of defects in the materials until the next
relevant maintenance operation
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.
All relevant properties such as material data, material conditions (e.g. humidity), pre-manufacturing
processes, etc. shall be specified to provide predictable and reproducible properties and functionality of
the product.
Material and component data applied in simulations shall be consistent with the specified properties.
All test specimen used in the validation process shall be manufactured in accordance with the
specifications to ensure the transferability to the product.
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
and/or processes to identify requirements that shall be fulfilled to validate the part.
4.2.2 Specifications
The specification of designed and manufactured parts using new material and/or processes corresponds
to the following points:
— trains that could be encountered. For example, category of rail vehicle. For example (L), (P), or (F) in
accordance with EN 12663-1 and C-I, C-II, C-III or C-IV in accordance with EN 15227;
— location of the part in the rail 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.;
— requirements such as lifetime, maintenance intervals, comfort, target price, weight, visual aspect,
geometries…. that could be subjected to change during the project;
— applicable regulations;
— recyclability.
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 or regulations to fulfil shall be identified as well as potential
complements asked or necessary modifications depending on the material and/or processes 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 at 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 is 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.
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 complex 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 it is mandatory by regulations or by the standards, or if the manufacturer needs to be more
representative of its design, it is necessary to carry out subset or full-scale tests and they shall be done at
this stage. If it is not the case, the design of 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 specified by standards or regulations. 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 and/or on track.
4.5.4 Is the subset or full-scale test validated?
If the subset or full-scale test cannot be validated according to the standard, regulations or additional
validation criteria for one or several requirements, the cause shall 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 should be modified and
all the affected requirements should be done.
4.5.5 Is fitting test results with calculation required?
If it is required by standard or regulations, a mutual verification between testing and simulation is
necessary and the appropriate parameters shall be recorded during testing by strain or stress
measurement (e.g. strain gauges, etc). These test results shall be compared to the corresponding results
of the simulation.
Deviations between test and simulation shall be investigated and the reason for the deviations shall be
identified.
4.6 Part validated
At this stage, the design part is validated regarding the overall specifications and requirements according
to the project of part with new materials and processes as shown in Figure 1.
Only the last iteration cycle of the successfully validated part, as it will be used in the rail vehicle (equal
material, equal design, equal manufacturing process) shall be included in the validation report to prepare
the homologation.
Figure 1 — Validation methodology flowchart
5 Requirements validation
5.1 Static and instability
5.1.1 General
Static and instability requirement is mainly covered by associated standards listed in Table 1.
Table 1 — Static and instability application standards and associated rolling stock components
Standards Rolling stock components
EN 12663 series 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 specify dedicated criteria depending on the material or processes.
NOTE This point will be dealt with in EN 18128-2 currently under development.
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 and instability
requirements applicable to all materials.
Additionally, the instability requirement includes local and global buckling depending on the material’s
sensitivity.
5.1.2 Preliminary design
5.1.2.1 General
According to the concept defined in 4.2, this first part aims, to validate static and instability of a rough
design in the part called “pre-design” with associated materials and processes.
5.1.2.2 Static and instability specifications
Definitions of all elements to validate for the static and instability requirements:
— associated standards listed in Table 1;
— associated load cases and derived load scenarios;
— other mandatory specifications.
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 manufacturers, 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 done 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 and instability 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 and instability requirement. It consists in checking if the stresses and strains are below
maximum admissible values.
In addition to the maximum admissible values, safety factors shall be considered if they are mandatory
by the standards. Their values are determined according to the structural category of the part (primary,
secondary, non-structural parts), materials, processes, manufacturing conditions, maintenance intervals,
etc.
For instability, the criterion does not apply for parts of the structure which are specifically designed to
collapse in a controlled manner (e.g. as required by passive safety design).
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 Do you need more materials and processes data?
Since, for most of materials, mechanical properties strongly depend on the manufacturing process, it is
preferable to carry out static and instability elementary tests on specimens processed by the
manufacturer of the part to be more representative of the materials data used for the calculation,
compared to data sheets, literature, etc.
Furthermore, these tests could allow to reduce the value of the specified safety factors.
5.1.2.7 Static and instability elementary testing on specimens
This part corresponds to carrying out static and instability elementary tests on specimens manufactured
with materials and processes selected in 5.1.2.3.1. The different static and instability elementary tests
will be chosen regarding the selected materials and processes according to the existing test standards or
specific tests. 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 and instability 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 and instability 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” (e.g. 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 done
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 and instability calculation of the advanced 3D design model
At this stage, static and instability criteria values of the advanced 3D design model are calculated by FEA
or equivalent analytics. Static and instability criteria are chosen regarding materials such as Von Mises
for isotropic materials, Tsai Wu for composite materials, etc.
5.1.3.4 Aare static and instability criteria values below maximum admissible values?
This step allows iterations to validate by FEA, 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.
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 Do you need more 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 representative on the static assembly data and be
able to reduce the value of the specified safety factors.
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 and instability requirement validated
At this stage, the part is validated regarding static requirement according to the project of part with new
materials as shown in the Figure 2.
At this stage, the design of the part is validated regarding static and instability requirements with new
materials and/or processes as shown in the Figure 2.

Figure 2 — Static and instability 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 — Overview Fatigue standards for railway applications
Fatigue standards Rolling stock components
EN 12663 series Carbody and equipment
EN 13749 Bogie
These listed standards cannot necessarily be fully applied to non-metallic materials. For example, they
do not cover fatigue criteria regarding to the stiffness degradation as it could be an issue to composite
materials. In addition, they do not 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.
NOTE These criteria will be dealt with in EN 18128-2 currently under development.
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.
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 manufacturer, 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 as 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. 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 Do you need more materials and processes data?
Since for many materials, mechanical properties strongly depend on the manufacturing process, it is
preferable to carry out fatigue elementary tests on specimens processed by the manufacturer of the part.
This gives more representativity on the materials data used for the calculation compared to data sheets,
literature, etc.
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. 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 manufacturer, 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
done 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 (e.g. 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 FEA methods can be used for this
purpose);
— include adequate and justified safety margins;
— specific and detailed data (from manufacturer, 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 Do you need more 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 representative on the assembly data and then reduce the
value of specified safety factors
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 as shown in the Figure 3.

Figure 3 — Fatigue requirement flowchart
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