Space engineering - Structural factors of safety for spaceflight hardware

The purpose of this Standard is to define the Factors Of Safety (FOS), Design Factor and additional factors to be used for the dimensioning and design verification of spaceflight hardware including qualification and acceptance tests.
This standard is not self standing and is used in conjunction with the ECSS-E-ST-32, ECSS-E-ST-32-02 and ECSS-E-ST-33-01 documents.
Following assumptions are made in the document:
-   that recognized methodologies are used for the determination of the limit loads, including their scatter, that are applied to the hardware and for the stress analyses;
-   that the structural and mechanical system design is amenable to engineering analyses by current state-of-the-art methods and is conforming to standard aerospace industry practices.
Factors of safety are defined to cover chosen load level probability, assumed uncertainty in mechanical properties and manufacturing but not a lack of engineering effort.
The choice of a factor of safety for a program is directly linked to the rationale retained for designing, dimensioning and testing within the program. Therefore, as the development logic and the associated reliability objectives are different for:
-   unmanned scientific or commercial satellite,
-   expendable launch vehicles,
-   man-rated spacecraft, and
-   any other unmanned space vehicle (e.g. transfer vehicle, planetary probe)
specific values are presented for each of them.
Factors of safety for re-usable launch vehicles and man-rated commercial spacecraft are not addressed in this document.
For all of these space products, factors of safety are defined hereafter in the document whatever the adopted qualification logic: proto-flight or prototype model.
For pressurized hardware, factors of safety for all loads except internal pressure loads are defined in this standard. Concerning the internal pressure, the factors of safety for pressurised hardware can be found in ECSS-E-ST-32-02. For loads combination refer to ECSS-E-ST-32-02.
For mechanisms, specific factors of safety associated with yield and ultimate of metallic materials, cable rupture factors of safety, stops/shaft shoulders/recess yield factors of safety and limits for peak Hertzian contact stress are specified in ECSS-E-ST-33-01.
Alternate approach
The factors of safety specified hereafter are applied using a deterministic approach i.e. as generally applied in the Space Industry to achieve the structures standard reliability objectives. Structural safety based on a probabilistic analysis could be an alternate approach but it has to be demonstrated this process achieves the reliability objective specified to the structure. The procedure is approved by the customer.
This standard may be tailored for the specific characteristics and constraints of a space project in conformance with ECSS-S-ST-00.

Raumfahrttechnik - Strukturelle Sicherheitsfaktoren für Raumflughardware

Ingénierie spatiale - Facteurs de sécurité pour les structures spatiales

La présente norme a pour objet de définir les Coefficients de sécurité (CS), le Coefficient de sécurité nominal et des coefficients additionnels à utiliser pour vérifier le dimensionnement et la conception de matériels spatiaux, y compris dans le cadre d'essais de qualification et de recette.
La présente norme n'est pas indépendante ; elle est utilisée conjointement avec les documents ECSS-E-ST-32, ECSS-E-ST-32-02 et ECSS-E-ST-33-01.
Dans le présent document, les hypothèses suivantes sont émises :
- des méthodologies reconnues sont utilisées pour déterminer les charges limites appliquées aux matériels, y compris leur répartition, et pour analyser les contraintes ;
- la conception structurelle et mécanique du système peut faire l'objet d'analyses techniques conduites au moyen de méthodes de pointe et répond aux pratiques normalisées de l'industrie aérospatiale.
Les coefficients de sécurité sont définis de façon à couvrir la probabilité du niveau de charge choisi, l'incertitude supposée en termes de propriétés mécaniques et de fabrication, exception faite de toute lacune potentielle concernant les efforts d'ingénierie.
Le choix d'un coefficient de sécurité pour un programme est directement lié à la justification retenue pour la conception, le dimensionnement et les essais réalisés dans le cadre du programme. Par conséquent, la logique de développement et les objectifs de fiabilité diffèrent pour :
- les satellites scientifiques ou commerciaux non habités ;
- les lanceurs non récupérables ;
- les engins spatiaux répondant aux exigences de sécurité d'un vol avec équipage ; et
- tout autre véhicule spatial non habité (par exemple : un véhicule de transfert, une sonde spatiale).
Des valeurs spécifiques sont présentées pour chacun de ces éléments.
Le présent document ne traite pas des coefficients de sécurité destinés aux lanceurs réutilisables et aux engins spatiaux commerciaux répondant aux exigences de sécurité d'un vol avec équipage.
Pour tous ces produits spatiaux, les coefficients de sécurité sont définis ci-après dans le document, quelle que soit la logique de qualification adoptée : modèle protovol ou modèle de prototype.
Pour le matériel sous pression, les coefficients de sécurité sont définis dans la présente norme pour toutes les charges, exception faite des charges de pressurisation interne. Concernant la pressurisation interne, les coefficients de sécurité pour le matériel sous pression peuvent être consultés dans le document ECSS-E-ST-32-02. Pour les combinaisons de charges, se reporter au document ECSS-E-ST-32-02.
Pour les mécanismes, les coefficients de sécurité spécifiques liés au fluage et à la rupture des matériaux métalliques, les coefficients de sécurité liés à la rupture des câbles, les coefficients de sécurité de fluage liés aux épaulements/décrochements d'arbres/butées et les limites fixées pour la contrainte maximale de contact de Hertz sont spécifiés dans le document ECSS-E-ST-33-01.
Approche alternative
Les coefficients de sécurité spécifiés ci-après sont appliqués à l'aide d'une démarche déterministe, c'est-à-dire tels qu'ils sont généralement appliqués dans l'industrie spatiale pour atteindre les objectifs de fiabilité des structures normalisés. La sécurité de la structure fondée sur une analyse probabiliste pourrait être une approche alternative ; néanmoins, il est impératif de démontrer que ce processus atteint l'objectif de fiabilité spécifié pour la structure concernée. La procédure est approuvée par le client.
La présente norme peut être adaptée aux caractéristiques et contraintes spécifiques d’un projet spatial, conformément à l’ECSS-S-ST-00.

Vesoljska tehnika - Strukturni varnostni faktorji za strojne dele vesoljskih plovil

General Information

Status
Published
Public Enquiry End Date
27-Nov-2019
Publication Date
21-Jun-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
17-Jun-2020
Due Date
22-Aug-2020
Completion Date
22-Jun-2020

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SLOVENSKI STANDARD
SIST EN 16603-32-10:2020
01-september-2020
Nadomešča:
SIST EN 16603-32-10:2014

Vesoljska tehnika - Strukturni varnostni faktorji za strojne dele vesoljskih plovil

Space engineering - Structural factors of safety for spaceflight hardware
Raumfahrttechnik - Strukturelle Sicherheitsfaktoren für Raumflughardware
Ingénierie spatiale - Facteurs de sécurité pour les structures spatiales
Ta slovenski standard je istoveten z: EN 16603-32-10:2020
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
SIST EN 16603-32-10:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 16603-32-10:2020
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SIST EN 16603-32-10:2020
EUROPEAN STANDARD
EN 16603-32-10
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2020
ICS 49.140
Supersedes EN 16603-32-10:2014
English version
Space engineering - Structural factors of safety for
spaceflight hardware

Ingénierie spatiale - Coefficients de sécurité de la Raumfahrttechnik - Strukturelle Sicherheitsfaktoren

structure pour les matériels spatiaux für Raumflughardware
This European Standard was approved by CEN on 24 May 2020.

CEN and CENELEC 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 and CENELEC 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 and CENELEC member into its own language and notified to the CEN-CENELEC

Management Centre has the same status as the official versions.

CEN and CENELEC members are the national standards bodies and national electrotechnical committees 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.
CEN-CENELEC Management Centre:
Rue de la Science 23, B-1040 Brussels

© 2020 CEN/CENELEC All rights of exploitation in any form and by any means Ref. No. EN 16603-32-10:2020 E

reserved worldwide for CEN national Members and for
CENELEC Members.
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SIST EN 16603-32-10:2020
EN 16603-32-10:2020 (E)
Table of contents

European Foreword ................................................................................................... 4

1 Scope ....................................................................................................................... 5

2 Normative references ............................................................................................. 7

3 Terms, definitions and abbreviated terms ............................................................ 8

3.1 Terms and definitions ............................................................................................... 8

3.2 Terms specific to the present standard ..................................................................... 8

3.3 Abbreviated terms..................................................................................................... 9

3.4 Nomenclature ........................................................................................................... 9

4 Requirements ........................................................................................................ 11

4.1 Applicability of structural factors of safety ............................................................... 11

4.1.1 Overview ................................................................................................... 11

4.1.2 Applicability ............................................................................................... 11

4.1.3 General ..................................................................................................... 11

4.1.4 Design factor for loads .............................................................................. 11

4.1.5 Additional factors for design ...................................................................... 13

4.2 Loads and factors relationship ................................................................................ 14

4.2.1 General ..................................................................................................... 14

4.2.2 Specific requirements for launch vehicles ................................................. 16

4.3 Factors values ........................................................................................................ 16

4.3.1 Test factors ............................................................................................... 16

4.3.2 Factors of safety ....................................................................................... 18

Annex A (informative) Qualification test factor for launch vehicles ................... 22

Bibliography ............................................................................................................. 24

Figures

Figure 4-1: Logic for Factors of Safety application ................................................................ 15

Figure 4-2: Analysis tree ....................................................................................................... 16

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SIST EN 16603-32-10:2020
EN 16603-32-10:2020 (E)
Tables
Table 4-1: Relationship among (structural) factors of safety, design factors and

additional factors ................................................................................................ 15

Table 4-2: Test factor values ................................................................................................ 16

Table 4-3: Factors of safety for metallic, FRP, sandwich, glass and ceramic structural

parts ................................................................................................................... 19

Table 4-4: Factors of safety for joints, inserts and connections ............................................. 20

Table 4-5: Factors of safety for buckling ............................................................................... 21

Table 4-6: Factors of safety for pressurized hardware .......................................................... 21

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SIST EN 16603-32-10:2020
EN 16603-32-10:2020 (E)
European Foreword
This document (EN 16603-32-10:2020) has been prepared by Technical
Committee CEN/CLC/TC 5 “Space”, the secretariat of which is held by DIN.
This standard (EN 16603-32-10:2020) originates from ECSS-E-ST-32-10C Rev.2.
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 December
2020, and conflicting national standards shall be withdrawn at the latest by
December 2020.
Attention is drawn to the possibility that some of the elements of this document
may be the subject of patent rights. CEN [and/or CENELEC] shall not be held
responsible for identifying any or all such patent rights.
This document supersedes EN 16603-32-10:2014.
The main changes with respect to EN 16603-32-10:2014 are:
Added requirements:
• 4.3.2.1e; 4.3.2.2b.
Modified requirements:
• 4.1.2a NOTE moved to end (editorial); 4.3.2.1b, c and d (editorial); Table
4-3; Table 4-4.
Editorial corrections:
• Nomenclature added
• Change of “thermal induced loads” to “thermally induced loads”
• Bibliography updated
This document has been prepared under a standardization request given to
CEN by the European Commission and the European Free Trade Association.
This document has been developed to cover specifically space systems and has
therefore precedence over any EN covering the same scope but with a wider
domain of applicability (e.g. : aerospace).
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, Former Yugoslav Republic of Macedonia, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
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SIST EN 16603-32-10:2020
EN 16603-32-10:2020 (E)
Scope
The purpose of this Standard is to define the Factors Of Safety (FOS), Design
Factor and additional factors to be used for the dimensioning and design
verification of spaceflight hardware including qualification and acceptance
tests.
This standard is not self standing and is used in conjunction with the ECSS-E-
ST-32, ECSS-E-ST-32-02 and ECSS-E-ST-33-01 documents.
Following assumptions are made in the document:
• that recognized methodologies are used for the determination of the limit
loads, including their scatter, that are applied to the hardware and for the
stress analyses;
• that the structural and mechanical system design is amenable to
engineering analyses by current state-of-the-art methods and is
conforming to standard aerospace industry practices.
Factors of safety are defined to cover chosen load level probability, assumed
uncertainty in mechanical properties and manufacturing but not a lack of
engineering effort.

The choice of a factor of safety for a program is directly linked to the rationale

retained for designing, dimensioning and testing within the program.

Therefore, as the development logic and the associated reliability objectives are

different, specific values are presented for:
• unmanned scientific or commercial satellite,
• expendable launch vehicles,
• man-rated spacecraft, and
• any other unmanned space vehicle (e.g. transfer vehicle, planetary
probe).
Factors of safety for re-usable launch vehicles and man-rated commercial
spacecraft are not addressed in this document.
For all of these space products, factors of safety are defined hereafter in the
document whatever the adopted qualification logic: proto-flight or prototype
model.

For pressurized hardware, factors of safety for all loads except internal pressure

loads are defined in this standard. Concerning the internal pressure, the factors

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SIST EN 16603-32-10:2020
EN 16603-32-10:2020 (E)
of safety for pressurised hardware can be found in ECSS-E-ST-32-02. For loads
combination refer to ECSS-E-ST-32-02.
For mechanisms, specific factors of safety associated with yield and ultimate of

metallic materials, cable rupture factors of safety, stops/shaft shoulders/recess

yield factors of safety and limits for peak Hertzian contact stress are specified in

ECSS-E-ST-33-01.
Alternate approach
The factors of safety specified hereafter are applied using a deterministic
approach i.e. as generally applied in the Space Industry to achieve the
structures standard reliability objectives. Structural safety based on a
probabilistic analysis could be an alternate approach but it has to be
demonstrated this process achieves the reliability objective specified to the
structure. The procedure is approved by the customer.

This standard may be tailored for the specific characteristics and constraints of a

space project in conformance with ECSS-S-ST-00.
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SIST EN 16603-32-10:2020
EN 16603-32-10:2020 (E)
Normative references
The following normative documents contain provisions which, through
reference in this text, constitute provisions of this ECSS Standard. For dated
references, subsequent amendments to, or revision of any of these publications,
do not apply. However, parties to agreements based on this ECSS Standard are

encouraged to investigate the possibility of applying the more recent editions of

the normative documents indicated below. For undated references, the latest
edition of the publication referred to applies.
EN reference Reference in text Title
EN 16601-00-01 ECSS-S-ST-00-01 ECSS system – Glossary of terms
EN 16603-10-02 ECSS-E-ST-10-02 Space engineering – Verification
EN 16603-10-03 ECSS-E-ST-10-03 Space engineering – Testing
EN 16603-32 ECSS-E-ST-32 Space engineering – Structural general requirements

EN 16603-32-02 ECSS-E-ST-32-02 Space engineering – Structural design and verification

of pressurized hardware
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SIST EN 16603-32-10:2020
EN 16603-32-10:2020 (E)
Terms, definitions and abbreviated terms
3.1 Terms and definitions

For the purpose of this Standard, the terms and definitions from ECSS-S-ST-00-01,

ECSS-E-ST-10-02, ECSS-ST-E-10-03, and ECSS-E-ST-32 apply.
3.2 Terms specific to the present standard
3.2.1 local design factor (K )

factor used to take into account local discontinuities and applied in series with

FOSU or FOSY
3.2.2 margin policy factor (K )
factor, specific to launch vehicles, which includes the margin policy defined by
the project
3.2.3 model factor (K )
factor which takes into account the representativity of mathematical models
3.2.4 project factor (K )
factor which takes into account at the beginning of the project the maturity of
the design and its possible evolution and programmatic margins which cover
project uncertainties or some growth potential when required
3.2.5 prototype test
test performed on a separate flight-like structural test article
3.2.6 protoflight test
test performed on a flight hardware
3.2.7 test factors (KA and KQ)
factors used to define respectively the acceptance and the qualification test
loads
3.2.8 ultimate design factor of safety (FOSU)
multiplying factor applied to the design limit load in order to calculate the
design ultimate load
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SIST EN 16603-32-10:2020
EN 16603-32-10:2020 (E)
3.2.9 yield design factor of safety (FOSY)
multiplying factor applied to the design limit load in order to calculate the
design yield load
3.3 Abbreviated terms
For the purpose of this standard, the abbreviated terms from ECSS-S-ST-00-01
and the following apply.
Abbreviation Meaning
AL acceptance test load
DLL design limit load
DUL design ultimate load
DYL design yield load
FOS factor of safety
FOSU ultimate design factor of safety
FOSY yield design factor of safety
FRP fibre reinforced plastics
GSE ground support equipment
KA acceptance test factor
KQ qualification test factor
LCDA launch vehicle coupled dynamic analysis
LL limit load
N/A not applicable
QL qualification test load
S/C spacecraft
3.4 Nomenclature
The following nomenclature applies throughout this document:
a. The word “shall” is used in this Standard to express requirements. All
the requirements are expressed with the word “shall”.
b. The word “should” is used in this Standard to express recommendations.
All the recommendations are expressed with the word “should”.
NOTE It is expected that, during tailoring,
recommendations in this document are either
converted into requirements or tailored out.
c. The words “may” and “need not” are used in this Standard to express
positive and negative permissions, respectively. All the positive
permissions are expressed with the word “may”. All the negative
permissions are expressed with the words “need not”.
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SIST EN 16603-32-10:2020
EN 16603-32-10:2020 (E)
d. The word “can” is used in this Standard to express capabilities or
possibilities, and therefore, if not accompanied by one of the previous
words, it implies descriptive text.
NOTE In ECSS “may” and “can” have completely
different meanings: “may” is normative
(permission), and “can” is descriptive.
e. The present and past tenses are used in this Standard to express
statements of fact, and therefore they imply descriptive text.
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SIST EN 16603-32-10:2020
EN 16603-32-10:2020 (E)
Requirements
4.1 Applicability of structural factors of safety
4.1.1 Overview
The purpose of the factors of safety defined in this Standard is to guarantee an
adequate level of mechanical reliability for spaceflight hardware.
4.1.2 Applicability
a. The factors specified in clauses 4.1.4, 4.1.5 and 4.3 shall be applied for:
1. Structural elements of satellites including payloads, equipment
and experiments.
2. The expendable launch vehicles structural elements.
3. Man-rated spacecraft structures including payloads, equipments
and experiments.
NOTE These factors are not applied for the GSE sizing
and qualification.
b. The factors in clauses 4.1.4, 4.1.5 and 4.3 shall be applied for both the
design and test phases as defined in Figure 4-1.
4.1.3 General
a. Design factor and additional factors values shall be agreed with the
customer.
4.1.4 Design factor for loads
4.1.4.1 General
a. For determination of the Design Limit Load (DLL) the Design Factor shall
be used, this is defined as the product of the factors defined hereafter.
NOTE Robustness of the sizing process is considered
through the Design Limit Loads (DLL).
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SIST EN 16603-32-10:2020
EN 16603-32-10:2020 (E)
4.1.4.2 Model factor
a. A “model Factor" KM shall be applied to account for uncertainties in
mathematical models when predicting dynamic response, loads and
evaluating load paths.
NOTE 1 The model factor is applied at every level of the
analysis tree system (Figure 4-2) where predictive
models are used. It encompasses the lack of
confidence in the information provided by the
model, e.g. hyperstaticity (uncertainty
...

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