ISO 21347:2025
(Main)Space systems — Fracture and damage control
Space systems — Fracture and damage control
This document establishes general requirements for the application of fracture control technology to fracture-critical items (FCIs) fabricated from metallic, non-metallic or composite materials. It also establishes mechanical damage control requirements for mechanical-damage-critical items (MDCIs) fabricated from composite materials. These requirements, when implemented on a particular space system, can assure a high level of confidence in achieving safe operation and mission success. This document provides the minimum fracture control and mechanical damage control requirements for FCIs and MDCIs in general space systems, including launch vehicles, spacecraft and ground support equipment. With modifications, these requirements can also be applicable to reusable launch vehicles (RLVs). This document is not applicable to projects which already have a set of specific fracture and damage control requirements suitable for their special applications. This document is not applicable to processing detected defects.
Systèmes spatiaux — Maîtrise des fissurations et des dommages
L'ISO 21347:2005 définit des exigences générales pour appliquer la maîtrise des fissurations aux éléments critiques en fissuration (FCI) de fabrication métallique, non métallique ou composite. Elle définit également des exigences de maîtrise des dommages mécaniques pour des éléments critiques (MDCI) en matériaux composites. Ces exigences, une fois prises en compte sur un système spatial donné, peuvent assurer un haut degré de confiance en termes de sécurité de fonctionnement et de réussite de la mission. Les exigences exposées dans la présente Norme internationale sont les exigences minimales de maîtrise des fissurations et des dommages pour les FCI et MDCI dans les systèmes spatiaux généraux, y compris les lanceurs et les spationefs. Sous réserve des modifications qui s'imposent, ces exigences valent également pour les lanceurs réutilisables (RLV). La présente Norme internationale n'est applicable ni à la Navette et à ses charges utiles, ni à l'ISS et équipements associés, l'une et l'autre faisant l'objet d'exigences propres à leurs applications spécifiques. La présente Norme internationale n'est pas applicable au traitement des défauts détectés.
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International
Standard
ISO 21347
Second edition
Space systems — Fracture and
2025-08
damage control
Systèmes spatiaux — Maîtrise des fissurations et des dommages
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 9
5 Fracture and mechanical damage control requirements .10
5.1 Fracture control requirements .10
5.1.1 General .10
5.1.2 Fracture-critical item (FCI) classification .10
5.1.3 Fracture control plan .10
5.1.4 Damage tolerance requirements .11
5.1.5 Special provision .14
5.2 Mechanical damage control requirements .14
5.2.1 General .14
5.2.2 Mechanical damage critical item (MDCI) classification . .14
5.2.3 Mechanical damage control plan .14
5.3 Non-destructive evaluation (NDE) .16
5.4 Other special requirements .16
5.4.1 Non-fracture-critical item demonstration .16
5.4.2 Leak-before-burst (LBB) failure mode demonstration .19
5.4.3 Traceability and documentation .19
Annex A (informative) Fracture control implementation guidelines .20
Annex B (informative) Guidelines for mechanical damage control of composite-overwrapped
pressure vessels (COPV) .26
Bibliography .29
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 14, Space systems and operations.
This second edition cancels and replaces the first edition (ISO 21347:2005), which has been technically
revised.
The main changes are as follows:
— updates of the normative references and their citations in the text; organization of requirements in
structural-related ISO document to avoid duplication;
— updates of the terms and definitions to harmonize with the other structural-related ISO documents;
— update of approaches to classify non-fracture-critical items (non-FCI);
— addition of supplemental information in Annex A.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
To prevent premature structural failure due to the propagation of cracks or crack-like defects during a
structure’s service life, a fracture control policy is being imposed on space systems. These systems include
civil and military space vehicles, launch systems, and their related ground support equipment. For crewed
space flight systems, most procurement agencies have considered fracture control a human-safety-related
requirement. For example, the National Aeronautics and Space Administration (NASA) and the European
Space Agency (ESA) have required fracture control for all payloads using the NASA Space Shuttle (Shuttle)
and all equipment items installed on the International Space Station (ISS). These systems have established
specific fracture control requirements. These requirements have been implemented on all the payloads and
equipment items using the Shuttle and ISS.
Recently, many procurement agencies and range safety authorities have imposed fracture control
requirements on critical hardware items such as main propellant tanks of expendable launch vehicles (ELVs)
and high-pressure gas bottles used in uncrewed spacecraft in order to prevent loss of either life or launch
site facilities, or both. Mechanical damage control is also being required by many range safety authorities on
impact-damage-prone composite-overwrapped pressure vessels (COPVs). This document specifies uniform
fracture and mechanical damage control requirements for non-Shuttle and non-ISS hardware. It can be
applied to safety and mission critical structures and other hardware items.
v
International Standard ISO 21347:2025(en)
Space systems — Fracture and damage control
1 Scope
This document establishes general requirements for the application of fracture control technology
to fracture-critical items (FCIs) fabricated from metallic, non-metallic or composite materials. It also
establishes mechanical damage control requirements for mechanical-damage-critical items (MDCIs)
fabricated from composite materials. These requirements, when implemented on a particular space system,
can assure a high level of confidence in achieving safe operation and mission success.
This document provides the minimum fracture control and mechanical damage control requirements
for FCIs and MDCIs in general space systems, including launch vehicles, spacecraft and ground support
equipment. With modifications, these requirements can also be applicable to reusable launch vehicles
(RLVs). This document is not applicable to projects which already have a set of specific fracture and damage
control requirements suitable for their special applications.
This document is not applicable to processing detected defects.
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.
ISO 10786, Space systems — Structural components and assemblies
ISO 14623, Space systems - Pressure vessels and pressurized structures — Design and operation
ISO 21648, Space systems — Flywheel module design and testing
ISO 24638, Space systems — Pressure components and pressure system integration
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
burst strength after impact
BAI
actual burst pressure of a pressure vessel (3.37) after it has been subjected to an impact event
3.2
catastrophic hazard
potential risk situation that can result in loss of life, life-threatening or permanently disabling injury,
occupational illness, loss of an element of an interfacing crewed flight system, loss of launch site facilities, or
long-term detriment to the environment
3.3
composite material
combination of materials different in composition or form on a macro scale
Note 1 to entry: The constituents retain their identities in the composite.
Note 2 to entry: The constituents can normally be physically identified, and there is an interface between them.
Note 3 to entry: Composites include:
— fibrous (composed of fibres, usually in a matrix);
— laminar (layers of materials);
— hybrid (combination of fibrous and laminar).
Note 4 to entry: A bonded structure, such as metallic honeycomb sandwich, is not considered a composite structure in
this document.
[SOURCE: ISO 23020:2021, 3.1.6, modified— Note 3 and Note 4 to entry have been added.]
3.4
composite-overwrapped pressure vessel
COPV
pressure vessel (3.37) with a fibre-based composite system fully or partially encapsulating a liner
Note 1 to entry: The liner serves as a liquid or gas permeation barrier and can possibly carry substantial pressure
loads. The composite overwraps generally carry pressure and environmental loads.
Note 2 to entry: The COPV containing a metallic liner is referred to as a metal-lined COPV while the COPV containing a
non-metallic liner is referred to as a non-metal-lined COPV.
[SOURCE: ISO 10786, 3.11, modified —Note 1 to entry amended and Note 2 to entry has been added.]
3.5
crack
planar flaw (3.18) or linear discontinuity with a sharp tip radius
3.6
critical crack
crack (3.5) with sufficient size such that unstable growth will occur under the spec
...
International
Standard
ISO 21347
Second edition
Space systems — Fracture and
damage control
Systèmes spatiaux — Maîtrise des fissurations et des dommages
PROOF/ÉPREUVE
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
PROOF/ÉPREUVE
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 9
5 Fracture and mechanical damage control requirements .10
5.1 Fracture control requirements .10
5.1.1 General .10
5.1.2 Fracture-critical item (FCI) classification .10
5.1.3 Fracture control plan .10
5.1.4 Damage tolerance requirements .11
5.1.5 Special provision .14
5.2 Mechanical damage control requirements .14
5.2.1 General .14
5.2.2 Mechanical damage critical item (MDCI) classification . .14
5.2.3 Mechanical damage control plan .14
5.3 Non-destructive evaluation (NDE) .16
5.4 Other special requirements .16
5.4.1 Non-fracture-critical item demonstration .16
5.4.2 Leak-before-burst (LBB) failure mode demonstration .19
5.4.3 Traceability and documentation .19
Annex A (informative) Fracture control implementation guidelines .20
Annex B (informative) Guidelines for mechanical damage control of composite-overwrapped
pressure vessels (COPV) .26
Bibliography .29
PROOF/ÉPREUVE
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 14, Space systems and operations.
This second edition cancels and replaces the first edition (ISO 21347:2005), which has been technically
revised.
The main changes are as follows:
— updates of the normative references and their citations in the text; organization of requirements in
structural-related ISO document to avoid duplication;
— updates of the terms and definitions to harmonize with the other structural-related ISO documents;
— update of approaches to classify non-fracture-critical items (non-FCI);
— addition of supplemental information in Annex A.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
PROOF/ÉPREUVE
iv
Introduction
To prevent premature structural failure due to the propagation of cracks or crack-like defects during a
structure’s service life, a fracture control policy is being imposed on space systems. These systems include
civil and military space vehicles, launch systems, and their related ground support equipment. For crewed
space flight systems, most procurement agencies have considered fracture control a human-safety-related
requirement. For example, the National Aeronautics and Space Administration (NASA) and the European
Space Agency (ESA) have required fracture control for all payloads using the NASA Space Shuttle (Shuttle)
and all equipment items installed on the International Space Station (ISS). These systems have established
specific fracture control requirements. These requirements have been implemented on all the payloads and
equipment items using the Shuttle and ISS.
Recently, many procurement agencies and range safety authorities have imposed fracture control
requirements on critical hardware items such as main propellant tanks of expendable launch vehicles (ELVs)
and high-pressure gas bottles used in uncrewed spacecraft in order to prevent loss of either life or launch
site facilities, or both. Mechanical damage control is also being required by many range safety authorities on
impact-damage-prone composite-overwrapped pressure vessels (COPVs). This document specifies uniform
fracture and mechanical damage control requirements for non-Shuttle and non-ISS hardware. It can be
applied to safety and mission critical structures and other hardware items.
PROOF/ÉPREUVE
v
International Standard ISO 21347:2025(en)
Space systems — Fracture and damage control
1 Scope
This document establishes general requirements for the application of fracture control technology
to fracture-critical items (FCIs) fabricated from metallic, non-metallic or composite materials. It also
establishes mechanical damage control requirements for mechanical-damage-critical items (MDCIs)
fabricated from composite materials. These requirements, when implemented on a particular space system,
can assure a high level of confidence in achieving safe operation and mission success.
This document provides the minimum fracture control and mechanical damage control requirements
for FCIs and MDCIs in general space systems, including launch vehicles, spacecraft and ground support
equipment. With modifications, these requirements can also be applicable to reusable launch vehicles
(RLVs). This document is not applicable to projects which already have a set of specific fracture and damage
control requirements suitable for their special applications.
This document is not applicable to processing detected defects.
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.
ISO 10786, Space systems — Structural components and assemblies
ISO 14623, Space systems - Pressure vessels and pressurized structures — Design and operation
ISO 21648, Space systems — Flywheel module design and testing
ISO 24638, Space systems — Pressure components and pressure system integration
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
burst strength after impact
BAI
actual burst pressure of a pressure vessel (3.37) after it has been subjected to an impact event
3.2
catastrophic hazard
potential risk situation that can result in loss of life, life-threatening or permanently disabling injury,
occupational illness, loss of an element of an interfacing crewed flight system, loss of launch site facilities, or
long-term detriment to the environment
PROOF/ÉPREUVE
3.3
composite material
combination of materials different in composition or form on a macro scale
Note 1 to entry: The constituents retain their identities in the composite.
Note 2 to entry: The constituents can normally be physically identified, and there is an interface between them.
Note 3 to entry: Composites include:
— fibrous (composed of fibres, usually in a matrix);
— laminar (layers of materials);
— hybrid (combination of fibrous and laminar).
Note 4 to entry: A bonded structure, such as metallic honeycomb sandwich, is not considered a composite structure in
this document.
[SOURCE: ISO 23020:2021, 3.1.6, modified— Note 3 and Note 4 to entry have been added.]
3.4
composite-overwrapped pressure vessel
COPV
pressure vessel (3.37) with a fibre-based composite system fully or partially encapsulating a liner
Note 1 to entry: The liner serves as a liquid or gas permeation barrier and can possibly carry substantial pressure
loads. The composite overwraps generally carry pressure and environmental loads.
Note 2 to entry: The COPV containing a metallic liner is referred to as a metal-lined COPV while the COPV containing a
non-metallic liner is referred to as a non-metal-lined COPV.
[SOURCE: ISO 10786, 3.11, modified —Note 1 to entry amended and Note 2 to entry has been added.]
3.5
crack
planar flaw (3.18) or linear discontinuity with a sharp tip radius
3.6
critical crack
crack (3.5) with s
...
ISO/PRF 21347:2024(en)
ISO/TC 20/SC 14
Secretariat: ANSI
Date: 2025-11-2906-04
Space systems — Fracture and damage control
Systèmes spatiaux — Maîtrise des fissurations et des dommages
PROOF
ISO/PRF 21347:2025(en)
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO/PRF 21347:2025(en)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 12
5 Fracture and mechanical damage control requirements . 13
5.1 Fracture control requirements . 13
5.2 Mechanical damage control requirements . 17
5.3 Non-destructive evaluation (NDE) . 19
5.4 Other special requirements . 19
Annex A (informative) Fracture control implementation guidelines . 24
Annex B (informative) Guidelines for mechanical damage control of composite-overwrapped
pressure vessels (COPV) . 31
Bibliography . 34
iii
ISO/PRF 21347:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 14, Space systems and operations.
This second edition cancels and replaces the first edition (ISO 21347:2005), which has been technically
revised.
The main changes are as follows:
— — updates of the normative references and their citations in the text; organization of requirements in
structural-related ISO document to avoid duplication;
— — updates of the terms and definitions to harmonize with the other structural-related ISO documents;
— — update of approaches to classify non-fracture-critical items (non-FCI);
— — addition of supplemental information in Annex AAnnex A.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
ISO/PRF 21347:2025(en)
Introduction
To prevent premature structural failure due to the propagation of cracks or crack-like defects during a
structure’s service life, a fracture control policy is being imposed on space systems. These systems include
civil and military space vehicles, launch systems, and their related ground support equipment. For crewed
space flight systems, most procurement agencies have considered fracture control a human-safety-related
requirement. For example, the National Aeronautics and Space Administration (NASA) and the European
Space Agency (ESA) have required fracture control for all payloads using the NASA Space Shuttle (Shuttle) and
all equipment items installed on the International Space Station (ISS). These systems have established specific
fracture control requirements. These requirements have been implemented on all the payloads and
equipment items using the Shuttle and ISS.
Recently, many procurement agencies and range safety authorities have imposed fracture control
requirements on critical hardware items such as main propellant tanks of expendable launch vehicles (ELVs)
and high-pressure gas bottles used in uncrewed spacecraft in order to prevent loss of either life or launch site
facilities, or both. Mechanical damage control is also being required by many range safety authorities on
impact-damage-prone composite-overwrapped pressure vessels (COPVs). This document providesspecifies
uniform fracture and mechanical damage control requirements to thefor non-Shuttle and non-ISS hardware.
It can be applied to safety and mission critical structures and other hardware items.
v
DRAFT International Standard ISO/DIS 21347:2024(en)
Space systems — Fracture and damage control
1 Scope
This document establishes general requirements for the application of fracture control technology to fracture-
critical items (FCIs) fabricated from metallic, non-metallic or composite materials. It also establishes
mechanical damage control requirements for mechanical-damage-critical items (MDCIs) fabricated from
composite materials. These requirements, when implemented on a particular space system, can assure a high
level of confidence in achieving safe operation and mission success.
This document provides the minimum fracture control and mechanical damage control requirements for FCIs
and MDCIs in general space systems, including launch vehicles, spacecraft and ground support equipment.
With necessary modifications, these requirements can also be applicable to reusable launch vehicles (RLVs).
This document is not applicable to projects which already have a set of specific fracture and damage control
requirements suitable for their special applications.
This document is not applicable to processing detected defects.
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.
ISO 10786, Space systems — Structural components and assemblies
ISO 14623, Space systems - Pressure vessels and pressurized structures — Design and operation
ISO 21648, Space systems — Flywheel module design and testing
ISO 24638, Space systems — Pressure components and pressure system integration
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/
3.1 3.1
burst strength after impact
BAI
actual burst pressure of a pressure vessel (3.37(3.37)) after it has been subjected to an impact event
ISO/PRF 21347:2025(en)
3.2 3.2
catastrophic hazard
potential risk situation that can result in loss of life, life-threatening or permanently disabling injury,
occupational illness, loss of an element of an interfacing crewed flight system, loss of launch site facilities, or
long-term detriment to the environment
3.3 3.3
composite material
combination of materials different in composition or form on a macro scale
Note 1 to entry: The constituents retain their identities in the composite.
Note 2 to entry: The constituents can normally be physically identified, and there is an interface between them.
Note 3 to entry: Composites include:
— — fibrous (composed of fibres, usually in a matrix);
— — laminar (layers of materials);
— — hybrid (combination of fibrous and laminar).
Note 4 to entry: A bonded structure, such as metallic honeycomb sandwich, is not considered as a composite structure in
this document.
[SOURCE: ISO 23020:2021, 3.1.6, modified— Note 3 and Note 4 to entry has been added.]
3.4
[SOURCE: ISO 23020:2021, 3.1.6, modified— Note 3 and Note 4 to entry have been added.]
3.4
composite-overwrapped pressure vessel
COPV
pressure vessel (3.37(3.37)) with a fibre-based composite system fully or partially encapsulating a liner
Note 1 to entry: The liner serves as a liquid or gas permeation barrier and may or may notcan possibly carry substantial
pressure loads. The composite overwraps generally carry pressure and environmental loads.
Note 2 to entry: The COPV containing a metallic liner is referred to as a metal-lined COPV while the COPV containing a
non-metallic liner is referred to as a non-metal-lined COPV.
[SOURCE: ISO 10786, 3.11, modified —Note 2 to entry has been added.]
3.5
[SOURCE: ISO 10786, 3.11, modified —Note 1 to entry amended and Note 2 to entry has been added.]
3.5
crack
planar flaw (3.18(3.18)) or linear discontinuity with a sharp tip radius
3.43.6 3.6
critical crack
crack (3.5) with sufficient size such that unstable growth will occur under the specific operating load and
environment
ISO/PRF 21347:2025(en)
3.7
critical flaw
specific shape of flaw (3.18crack (3.5)) with sufficient size such that unstable growth will occur under the
specific operating load and environment
3.7
critical flaw
specific shape of flaw (3.18) with sufficient size such that unstable growth will occur under the specific
operating load and environment
[SOURCE: ISO 14623:2003, 2.13]
3.8[SOURCE: ISO 14623:2003, 2.13]
3.53.8
damage tolerance
ability of a structure or a component of a structural assembly to resist failure due to the presence of flaws
(3.18(3.18),), for a specified period of unrepaired usage
[SOURCE: ISO 10786:2011, 3.13, modified —The wording, “cracks, or other damage” placed after “flaws”,
has been deleted.]
3.9[SOURCE: ISO 10786:2011, 3.13, modified —The wording “cracks, or other damage”, placed after “flaws”,
has been deleted.]
3.63.9
damage tolerance life
safe life
design criterion under which failure due to the presence of flaws does not occur in the
expected environment during the service life (3.46(3.46))
Note 1 to entry: In this design criterion, a flaw (3.18(3.18)) is assumed consistent with the inspection process specified
and it is shown that the largest undetected flaw that couldcan exist in the structure will not grow to failure in durations
multiplying life factors (3.25(3.25)) to service lifetimes when subjected to the cyclic and sustained loads in the
environments encountered.
3.73.10 3.10
damage tolerance life
safe life
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