EN 16603-32-01:2021
(Main)Space engineering - Fracture control
Space engineering - Fracture control
This ECSS Engineering Standard specifies the fracture control requirements to be imposed on space segments of space systems and their related GSE. The fracture control programme is applicable for space systems and related GSE when required by ECSS-Q-ST-40 or by the NASA document NST 1700.7, incl. ISS addendum. The requirements contained in this Standard, when implemented, also satisfy the fracture control requirements applicable to the NASA STS and ISS as specified in the NASA document NSTS 1700.7 (incl. the ISS Addendum). The NASA nomenclature differs in some cases from that used by ECSS. When STS/ISS-specific requirements and nomenclature are included, they are identified as such.
This standard may be tailored for the specific characteristic and constrains of a space project in conformance with ECSS-S-ST-00.
Raumfahrttechnik - Überwachung des Rissfortschritts
Ingénierie spatiale - Maîtrise de la rupture
La présente norme technique ECSS définit les exigences de maîtrise de la rupture
applicables aux segments des systèmes spatiaux et de leur ESS.
Ce programme de maîtrise de la rupture s'applique aux systèmes spatiaux et aux ESS
associés pour lesquels une défaillance structurelle peut être à l'origine d'un risque
catastrophique conformément à la définition d'un document applicable au lieu de l'ECSSQ-
ST-40, spécifié par le client comme ceux qui s'appliquent à l'ISS, aux systèmes
d'exploration ou aux charges utiles.
Le cas échéant, les exigences contenues dans la présente norme satisfont également aux
obligations de maîtrise de la rupture applicables aux matériels de la NASA et de l'ISS.
Dans certains cas, la nomenclature de la NASA est différente de celle utilisée par l'ECSS.
Lorsque des exigences et une nomenclature propres à l'ISS ou à l'exploration sont
mentionnées, elles sont identifiées en tant que telles.
La présente norme peut être adaptée aux caractéristiques et contraintes spécifiques d'un
projet spatial, conformément à l'ECSS-S-ST-00.
Vesoljska tehnika - Kontrola razpok
Ta tehnični standard ECSS določa zahteve za kontrolo razpok, ki se izvaja na vesoljskih delih vesoljskih sistemov in njihovih povezanih GSE. Program za kontrolo razpok velja za vesoljske sisteme in z njimi povezane GSE, če to zahteva standard ECSS-Q-ST-40 ali Nasin dokument NST 1700.7, vklj. z dodatkom ISS. Ko se izvajajo zahteve iz tega standarda, te izpolnjujejo tudi zahteve za kontrolo razpok, ki veljajo za NASA STS in ISS, kot je določeno v Nasinem dokumentu NSTS 1700.7 (vklj. z dodatkom ISS). Nasina nomenklatura se v nekaterih primerih razlikuje od tiste, uporabljene pri ECSS. Ko so vključene zahteve, določene s STS/ISS, in nomenklatura, so prepoznane kot take.
Ta standard se lahko prilagodi posameznim lastnostim in omejitvam vesoljskega projekta v skladu s standardom ECSS-S-ST-00.
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
01-marec-2022
Nadomešča:
SIST EN 16603-32-01:2014
Vesoljska tehnika - Kontrola razpok
Space engineering - Fracture control
Raumfahrttechnik - Überwachung des Rissfortschritts
Ingénierie spatiale - Maîtrise de la rupture
Ta slovenski standard je istoveten z: EN 16603-32-01:2021
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN 16603-32-01
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2021
ICS 49.140
Supersedes EN 16603-32-01:2014
English version
Space engineering - Fracture control
Ingénierie spatiale - Maîtrise de la rupture Raumfahrttechnik - Überwachung des Rissfortschritts
This European Standard was approved by CEN on 5 December 2021.
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
© 2021 CEN/CENELEC All rights of exploitation in any form and by any means
Ref. No. EN 16603-32-01:2021 E
reserved worldwide for CEN national Members and for
CENELEC Members.
Table of contents
European Foreword . 6
1 Scope . 8
2 Normative references . 9
3 Terms, definitions and abbreviated terms . 10
3.1 Terms from other standards . 10
3.2 Terms specific to the present standard . 11
3.3 Abbreviated terms. 16
3.4 Nomenclature . 18
4 Principles . 19
5 Fracture control programme . 21
5.1 General . 21
5.2 Fracture control plan . 22
5.3 Reviews . 22
5.3.1 General . 22
5.3.2 Safety and project reviews . 22
6 Identification and evaluation of PFCI . 24
6.1 Identification of PFCIs . 24
6.2 Evaluation of PFCIs . 27
6.2.1 Damage tolerance . 27
6.2.2 Fracture critical item classification . 29
6.3 Compliance procedures . 29
6.3.1 General . 29
6.3.2 Safe life items . 30
6.3.3 Fail-safe items . 30
6.3.4 Contained and restrained items. 31
6.3.5 Low-risk fracture items . 32
6.4 Documentation requirements . 38
6.4.1 Fracture control plan . 38
6.4.2 Lists . 38
6.4.3 Analysis and test documents . 38
6.4.4 Fracture control summary report . 38
7 Fracture mechanics analysis . 40
7.1 General . 40
7.2 Analytical life prediction . 41
7.2.1 Identification of all load events . 41
7.2.2 Identification of the most critical location and orientation of the crack . 42
7.2.3 Derivation of stresses for the critical location. 42
7.2.4 Derivation of the stress spectrum . 42
7.2.5 Derivation of material data . 43
7.2.6 Identification of the initial crack size and shape . 44
7.2.7 Identification of an applicable stress intensity factor solution . 46
7.2.8 Performance of crack growth calculations . 47
7.3 Critical crack-size calculation . 47
8 Special requirements . 49
8.1 Introduction . 49
8.2 Pressurized hardware . 49
8.2.1 General . 49
8.2.2 Pressure vessels . 50
8.2.3 Pressurized structures . 51
8.2.4 Pressure components, including lines and fittings . 52
8.2.5 Low risk sealed containers . 53
8.2.6 Hazardous fluid containers . 53
8.2.7 Pressurized components with non-hazardous LBB failure mode . 54
8.3 Welds . 54
8.3.1 Nomenclature . 54
8.3.2 Safe life analysis of welds . 55
8.4 Composite, bonded and sandwich structures . 56
8.4.1 General . 56
8.4.2 Defect assessment. 56
8.4.3 Damage threat assessment . 58
8.4.4 Compliance procedures . 60
8.5 Non-metallic items other than composite, bonded, sandwich and glass items . 62
8.6 Rotating machinery . 63
8.7 Glass components . 63
8.8 Fasteners . 64
8.9 Alloys treated with electric discharge manufacturing (EDM) . 65
9 Material selection . 66
10 Quality assurance and NDT . 67
10.1 Overview . 67
10.2 Nonconformances. 67
10.3 NDT of PFCI . 67
10.3.1 General . 67
10.3.2 NDT of raw material . 69
10.3.3 NDT of safe life finished items . 69
10.4 Non-destructive testing of metallic materials . 70
10.4.1 <> . 70
10.4.2 NDT categories versus initial crack size . 70
10.4.3 <> . 71
10.5 <> . 72
10.5.1 <> . 72
10.5.2 <> . 73
10.6 Traceability . 73
10.6.1 General . 73
10.6.2 Requirements . 74
10.7 Detected defects . 74
10.7.1 General . 74
10.7.2 Acceptability verification . 75
10.7.3 Improved probability of detection . 76
11 Reduced fracture control programme . 77
11.1 Applicability. 77
11.2 Requirements . 77
11.2.1 General . 77
11.2.2 Modifications . 77
Annex A (informative) The ESACRACK software package . 84
Annex B (informative) References . 85
Bibliography . 86
Figures
Figure 5-1: < . 22
Figure 6-1: Identification of PFCI . 26
Figure 6-2: Fracture control evaluation procedures . 28
Figure 6-3: Safe life item evaluation procedure for metallic materials . 35
Figure 6-4: Safe life item evaluation procedure for composite, bonded and sandwich
items . 36
Figure 6-5: Evaluation procedure for fail-safe items . 37
Figure 7-1: Initial crack geometries for parts without hole . 45
Figure 7-2: Initial crack geometries for parts with holes . 46
Figure 7-3: Initial crack geometries for cylindrical parts . 46
Figure 8-1: Procedure for metallic pressure vessel and metallic liner evaluation . 51
Figure 10-1: <> . 72
Figure 10-2: <> . 72
Figure 10-3: <> . 72
Tables
Table 8-1: Factor on stress for sustained crack growth analysis of glass items . 64
Table 10-1: <> . 71
European Foreword
This document (EN 16603-32-01:2021) has been prepared by Technical
Committee CEN/CLC/TC 5 “Space”, 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 June 2022,
and conflicting national standards shall be withdrawn at the latest by June 2022.
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 16603-32-01:2014.
The main changes with respect to EN 16603-32-01:2014 are listed below:
• Implementation of change requests
• Replacement of term “non-destructive inspection (NDI)” by “non-destructive
testing (NDT)” in the whole document
• Update of Scope
• Removal of information about the NASA Space Shuttle program (STS)
• Update of Normative References and Terms, definitions and abbreviated
terms
• Addition of Nomenclature
• Addition of clause 8.2.7 “Pressurized components with non-hazardous LBB
failure mode”
• Addition of clause 8.9 “Alloys treated with electric discharge manufacturing
(EDM)”
• Addition of clause 11.2.2.5 “Safe life composite, bonded and sandwich
structures”
• Addition of clause 11.2.2.6 “Metallic parts classified as PFCI according to
11.2.2.1”
• Addition of clause 11.2.2.7 “Fasteners classified as PFCI according to 11.2.2.1”
• Addition of clause 11.2.2.8 “NDT of fusion welded joints in pressure
components, as per 10.3.1p”
• Several clauses and requirements moved to EN 16602-70-15 (equivalent to
ECSS-Q-ST-70-15)
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.
Scope
This ECSS Engineering Standard specifies the fracture control requirements to
be imposed on space segments of space systems and their related GSE.
The fracture control programme is applicable for space systems and related
GSE where structural failure can result in a catastrophic hazard in accordance
with the definition of ECSS-Q-ST-40 or alternative applicable document
specified by the customer like those applicable to the ISS or Exploration systems
or payloads.
The requirements contained in this Standard, when implemented, also satisfy
the fracture control requirements applicable to the NASA and ISS hardware.
The NASA nomenclature differs in some cases from that used by ECSS. When
ISS or Exploration-specific requirements and nomenclature are included, they
are identified as such.
This standard may be tailored for the specific characteristic and constrains of a
space project in conformance with ECSS-S-ST-00.
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
EN 16602-20 ECSS-Q-ST-20 Space product assurance – Quality assurance
EN 16602-40 ECSS-Q-ST-40 Space product assurance – Safety
EN 16602-70 ECSS-Q-ST-70 Space product assurance – Materials, mechanical parts
and processes
EN 16602-70-15 ECSS-Q-ST-70-15 Space product assurance - Non-destructive testing
ECSS-Q-ST-70-36 Space product assurance – Material selection for
controlling stress-corrosion cracking
ECSS-Q-ST-70-45 Space product assurance – Mechanical testing of metallic
materials
DOT/FAA/AR- Metallic Materials Properties Development and
MMPDS Standardization (MMPDS) (former MIL-HDBK-5)
EN ISO 6520-1 Welding and allied processes – Classification of geometric
imperfections in metallic materials – Part 1: Fusion
welding
ISO 17659 Welding – Multilingual terms for welded joints with
illustrations
Terms, definitions and abbreviated terms
3.1 Terms from other standards
a. For the purpose of this Standard, the terms and definitions from ECSS-
ST-00-01 apply, in particular for the following terms:
1. catastrophic
2. customer
NOTE In this standard, the customer is considered to
represent the responsible fracture control or
safety authority.
3. hazard
b. For the purpose of this Standard, the following terms and definitions
from ECSS-E-ST-32 apply:
1. flaw
NOTE The term defect is used as synonymous.
2. maximum design pressure (MDP)
3. service life
4. proof test
5. limit load
6. structure
7. safe life
c. For the purpose of this Standard, the following terms and definitions
from ECSS-E-ST-32-02 apply:
1. burst pressure
2. hazardous fluid container
3. leak before burst, LBB
4. pressure component
5. pressure vessel
6. pressurized structure
7. sealed container
8. special pressurized equipment
9. visual damage threshold, VDT
NOTE 1 For typical implementation of thin-walled
composite structure, the VDT is sometimes
more specifically defined as the impact energy
of an impactor with a hemi-spherical tip of 16
mm diameter resulting in 0,3 mm or more
remaining surface deflection, after sufficiently
long time to cover potential evolution of the
indentation over time (due to e.g. wet ageing,
fatigue loading, viscoelasticity of the resin)
between impact and non-destructive testing.
NOTE 2 It can be time consuming to determine the VDT
based on remaining surface deflection of
0,3 mm (see NOTE 1) after a sufficiently long
time. Therefore, tests which cause mechanical
damage corresponding to a deflection of at least
1 mm, immediately after impact, are sometimes
used to determine the VDT.
10. non-hazardous LBB failure mode
d. For the purpose of this Standard, the following terms and definitions
from ECSS-Q-ST-70-15 apply:
1. close visual testing
2. special fracture control NDT
3. standard fracture control NDT
3.2 Terms specific to the present standard
3.2.1 aggressive environment
combination of liquid or gaseous media and temperature that alters static or
fatigue crack-growth characteristics from normal behaviour associated with an
ambient temperature and laboratory air environment
3.2.2 analytical life
life evaluated analytically by crack-growth analysis or fatigue analysis
3.2.3 containment
damage tolerance design principle that, if a part fails, prevents the propagation
of failure effects beyond the container boundaries
NOTE 1 A contained part is not considered PFCI, unless
its release can cause a hazard inside the
container. The container is a PFCI, and its
structural integrity after impact is verified as
part of fracture control activities.
NOTE 2 In this standard, the term containment in most
cases also covers items which are e.g. restrained
by a tether to prevent the occurrence of
hazardous events due to failure of the item.
3.2.4 crack-like defect
defect that has the same mechanical behaviour as a crack
NOTE 1 “Crack” and “crack-like defect” are considered
synonymous in this standard.
NOTE 2 Crack-like defects can, for example, be initiated
during material production, fabrication or
testing or developed during the service life of a
component.
NOTE 3 The term “crack-like defect” can include:
• For metallic materials flaws, inclusions,
pores and other similar defects.
• For non-metallic materials, debonding,
broken fibres, delamination, impact damage
and other specific defects depending on the
material.
3.2.5 crack aspect ratio, a/c
ratio of crack depth to half crack length
3.2.6 crack aspect ratio, a/c
ratio of crack depth to crack length
3.2.7 crack growth rate
rate of change of crack dimension with respect to the number of load cycles or
time
NOTE For example da/dN, dc/dN, da/dt and dc/dt.
3.2.8 crack growth retardation
reduction of crack-growth rate due to overloading of the cracked structural
member
3.2.9 critical crack size
the crack size at which the structure fails under the maximum specified load
NOTE The maximum specified load is in many cases
the limit load, but sometimes higher than the
limit load (e.g. for detected defects, composites
and glass items)
3.2.10 critical initial defect, CID
critical (i.e., maximum) initial crack size for which the structure can survive the
specified number of lifetimes.
3.2.11 critical stress-intensity factor
value of the stress-intensity factor at the tip of a crack at which unstable
propagation of the crack occurs
NOTE 1 This value is also called the fracture toughness.
The parameter KIC is the fracture toughness for
plane strain and is an inherent property of the
material. For stress conditions other than plane
strain, the fracture toughness is denoted KC or
K1e for part through cracks. In fracture
mechanics analyses, failure is assumed to be
imminent when the applied stress-intensity
factor is equal to or exceeds its critical value, i.e.
the fracture toughness. See 3.2.22.
NOTE 2 The term fracture toughness is used as a
synonymous.
3.2.12 cyclic loading
fluctuating load (or pressure) characterized by relative degrees of loading and
unloading of a structure
NOTE For example, loads due to transient responses,
vibro-acoustic excitation, flutter, pressure
cycling and oscillating or reciprocating
mechanical equipment.
3.2.13 damage tolerance threshold strain
maximum strain level below which damage
compatible with the sizes established by non-destructive testing (NDT), close
visual testing, the damage threat assessment, or the minimum sizes imposed
6 8
does not grow in 10 cycles (10 cycles for rotating hardware) at a load ratio
appropriate to the application
NOTE 1 Strain level is the maximum absolute value of
strain in a load cycle.
NOTE 2 The damage tolerance threshold strain is a
function of the material type and lay-up and is
determined from test data in the design
environment to the applicable or worst type
and orientation of strain and flaw for a
particular design and flaw size (e.g. the size
determined by the VDT).
NOTE 3 For definition of “close visual testing” see
ECSS-Q-ST-70-15.
3.2.14 damage tolerant
characteristic of a structure for which the amount of general degradation or the
size and distribution of local defects expected during operation, or both, do not
lead to structural degradation below specified performance
3.2.15 defect
see ‘flaw’ (3.1)
3.2.16 detected defect
defect known to exist in the hardware
3.2.17 fail-safe
damage-tolerance design principle, where a structure has
redundancy to ensure that failure of one structural element does not cause
general failure of the entire structure during the remaining lifetime
3.2.18 fastener
item that joins other structural items and transfers loads from one to the other
across a joint
3.2.19 fatigue
cumulative irreversible damage incurred by cyclic application of loads to
materials and structures
NOTE 1 Fatigue can initiate and extend cracks, which
degrade the strength of materials and
structures.
NOTE 2 Examples of factors influencing fatigue
behaviour of the material are the environment,
surface condition and part dimensions
3.2.20 fracture critical item
item classified as such
3.2.21 fracture limited life item
hardware item that requires periodic non-destructive re-testing or replacement
to be in conformance with fracture control requirements
3.2.22 fracture toughness
materials’ resistance to the unstable propagation of a crack
NOTE See critical stress intensity factor, 3.2.11.
3.2.23 initial crack size
maximum crack size, as defined by non-destructive testing, for performing a
fracture control evaluation
3.2.24 joint
element that connects other structural elements and transfers loads from one to
the other across a connection
3.2.25 load enhancement factor, LEF
factor to be applied on the load level of the spectrum of fatigue test(s) in order
to demonstrate with the test(s) a specified level of reliability and confidence
NOTE 1 The LEF is dependent upon the material or
construction, the number of test articles, and
the duration of the tests.
NOTE 2 MIL-HDBK-17F, Volume 3, Section 7.6.3 gives
an approach for calculating the LEF for
composite structures.
3.2.26 loading event
condition, phenomenon, environment or mission phase to which the structural
system is exposed and which induces loads in the structure
3.2.27 load spectrum
representation of the cumulative static and dynamic loadings anticipated for a
structural element during its service life
NOTE Load spectrum is also called load history.
3.2.28 mechanical damage
induced flaw in a composite hardware item that is caused by external
influences, such as surface abrasions, cuts, or impacts
3.2.29 potential fracture critical item, PFCI
item for which the initiation or propagation of cracks in structural items during
the service life can result in a catastrophic hazard
NOTE 1 Pressure vessels and rotating machinery are
always considered PFCI. See Figure 6-1.
NOTE 2 This can apply to other manned/human
missions.
3.2.30 R-ratio
ratio of the minimum stress to maximum stress
3.2.31 residual stress
stress that remains in the structure, owing to processing, fabrication, assembly
or prior loading
3.2.32 rotating machinery
rotating mechanical assembly that has a kinetic energy of 19300 joules or more,
or an angular momentum of 136 Nms or more
NOTE The amount of kinetic energy is based on 0,5 Iω
where I is the moment of inertia (kg.m ) and ω
is the angular velocity (rad/s).
3.2.33 stress-corrosion cracking, SCC
initiation or propagation, or both, of cracks, owing to the combined action of
applied sustained stresses, material properties and aggressive environmental
effects
NOTE The maximum value of the stress-intensity
factor for a given material at which no
environmentally induced crack growth occurs
at sustained load for the specified environment
is KISCC.
3.2.34 stress intensity factor, K
calculated quantity that is used in fracture mechanics analyses as a measure of
the stress-field intensity near the tip of an idealised crack
NOTE Calculated for a specific crack size, applied
stress level and part geometry. See 3.2.11.
3.2.35 structural screening
screening of structural elements with the objective to identify PFCI for the
complete structure
NOTE The structure includes components or
assemblies to sustain pressures, or to provide
containment (see ECSS-E-ST-32).
3.2.36 threshold stress intensity range, ∆K
th
stress-intensity range below which crack growth does not occur under cyclic
loading
3.2.37 variable amplitude spectrum
load spectrum or history whose amplitude varies with time
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
crack aspect ratio (see 3.2.5)
a/c
acceptance review
AR
American Society of Mechanical Engineers
ASME
American Society for Testing and Materials
ASTM
British Standard
BS
critical design review
CDR
critical initial defect
CID
composite overwrapped pressure vessel
COPV
United States Department of Transportation
DOT
document requirements definition
DRD
electrical discharge machining
EDM
European Standard
EN
elastic-plastic fracture mechanics
EPFM
Abbreviation Meaning
European Space Agency
ESA
failure assessment diagram
FAD
fracture-critical item
FCI
fracture-critical items list
FCIL
finite element
FE
fracture-limited life item
FLLI
fracture-limited life items list
FLLIL
foreign object debris
FOD
design tensile yield strength (in MPa)
Fty
design tensile ultimate strength (in MPa)
Ftu
ground support equipment
GSE
International Organisation for Standardisation
ISO
International Space Station
ISS
resistance curve based on J-integral
J-R curve
resistance curve based on stress intensity factor (K)
K-R curve
leak before burst
LBB
load enhancement factor
LEF
linear elastic fracture mechanics
LEFM
fracture toughness for stress conditions other than plane
KC
strain
NOTE: See NOTE 1 of definition 3.2.11.
plane strain fracture toughness
KIC
threshold stress-intensity factor for stress-corrosion cracking
KISCC
threshold stress-intensity range
∆Kth
maximum design pressure
MDP
maximum expected operating pressure
MEOP
National Aeronautics and Space Administration
NASA
non-destructive testing
NDT
non-hazardous leak before burst
NHLBB
National Space Transportation System (NASA Space Shuttle)
NSTS
preliminary design review
PDR
potential fracture-critical item
PFCI
potential fracture-critical items list
PFCIL
ratio of the minimum stress to maximum stress
R
reduced fracture-control programme
RFCP
Society of Automotive Engineers
SAE
Abbreviation Meaning
stress-corrosion cracking
SCC
international system of units
SI
system requirements review
SRR
ultrasonic
US
ultimate tensile strength
UTS
visual damage threshold
VDT
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”.
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.
Principles
The following assumptions and prerequisites are the basis of the
implementation of the requirements contained in this standard. They can be
used as reference for example when alternative approaches, not directly
covered by the requirements of this standard, are assessed for equivalent safety
or reliability.
• All structural elements contain crack-like defects located in the most
critical area of the component in the most unfavourable orientation. The
inability of non-destructive testing (NDT) techniques to detect such
defects does not negate this assumption, but merely establishes an upper
bound on the initial size of the cracks which result from these defects. For
conservatism, this crack size then becomes the smallest allowable size to
be used in any analysis or assessment.
• After undergoing a sufficient number of cycles at sufficiently high stress
amplitude, materials exhibit a tendency to propagate cracks, even in non-
aggressive environments.
• Whether, under cyclic or sustained tensile stress, a pre-existing (or load-
induced) crack does or does not propagate depends on:
the material behaviour with crack;
the initial size and geometry of the crack;
the presence of an aggressive environment;
the geometry of the item;
the magnitude and number of loading cycles;
the duration of sustained load;
the temperature of the material.
• For metallic materials, the engineering discipline of linear elastic fracture
mechanics (LEFM) provides analytical tools for the prediction of crack
propagation and critical crack size. Validity of LEFM, depends on stress
level, crack configuration and structural geometry. The engineering
discipline of elastic-plastic fracture mechanics (EPFM) provides analytical
tools for the prediction of crack initiation, stable ductile crack growth and
critical crack size.
• For non-metallic materials (other than glass and other brittle materials)
and fibre-reinforced composites (both with metal and with polymer
matrix), linear elastic fracture mechanics technology is agreed by most
authorities to be inadequate, with the exception of interlaminar fracture
mechanics applied to debonding and delamination. Fracture control of
these materials relies on the techniques of safe life assessment supported
by tests, containment, fail safe assessment, and proof testing.
Composite, bonded and sandwich items are manufactured and verified
to high quality control standards to assure aerospace quality hardware.
The hardware developer of composite, bonded and sandwich items uses
only manufacturing processes and controls (NDT, coupon tests, sampling
techniques, etc.) that are demonstrated to be reliable and consistent with
established aerospace industry practices for composite/bonded
structures.
• The observed scatter in measured material properties and fracture
mechanics analysis uncertainties is considered.
NOTE For example, scatter factor and LEF
• For ISS payloads and systems, entities controlling the pressure are two-
fault tolerant.
NOTE For example, regulators, relief devices and
thermal control systems
Fracture control programme
5.1 General
a. A fracture control programme shall be implemented by the supplier for
space systems and their related GSE in conformance with this Standard,
where structural failure can result in a catastrophic hazard in accordance
with the definition of ECSS-Q-ST-40 or alternative applicable document
specified by the customer.
NOTE Example of requirements superseding the ones
of ECSS-Q-ST-40: human spaceflight
requirements like those applicable to the ISS or
Exploration systems or payloads.
b. Fracture control requirements shall be applied for PFCIs identified in
accordance with requirements from clause 6.1.
c. Implementation of fracture control for structural GSE may be limited to
items which are not covered by other structural safety requirements.
NOTE In many cases this limits fracture control
verification to elements directly interfacing
with flight hardware.
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e. For unmanned, single-mission, space vehicles and their payloads, and
GSE the reduced fracture control programme, specified in clause 11, may
be implemented.
f. In case a project is rated highly critical by the customer due to other
aspects than the catastrophic hazard as defined in ECSS-Q-ST-40, the
applicability of this standard may be extended to mission critical
elements.
NOTE For each project, it is good practice that the
developer agrees with the customer the extent
of applicability of the standard to loss of system
and/or loss of mission hazards. It is
recommended that this agreement is achieved
as early as possible, preferably in the SOW and
then reflected in the Fracture Control Plan.
g. Due to the potential significant technical and programmatic impacts, an
extension of applicability of Fracture Control specified in 5.1f shall be
implemented with the baseline requirements specification and precise
identification of the elements that are subject of extension.
h. Extension of applicability of Fracture Control specified in 5.1f should be
defined prior to Phase B “Preliminary definition” as per ECSS-M-ST-10,
or equivalent project phase.
5.2 Fracture control plan
a. The supplier shall prepare and implement a fracture control plan in
conformance with ECSS-E-ST-32 ‘Fracture control plan – DRD’.
b. The fracture control plan shall be subject to approval by the customer.
Figure 5-1: <
5.3 Reviews
5.3.1 General
a. Fracture control activities and status shall be reported during all project
reviews.
NOTE For project reviews, see ECSS-M-ST-10.
5.3.2 Safety and project reviews
a. The schedule of fracture control activities shall be related to, and support,
the project safety review schedule.
NOTE As specified in ECSS-Q-ST-40, safety reviews
are performed in parallel with major project
reviews.
b. Fracture control documentation shall be provided for the reviews as
follows:
1. For a system requirements review (SRR)
The results of preliminary hazard analysis and fracture control
screening (which follows the methodology given in Figure 6-1) and
a written statement as to whether or not fracture control is
applicable.
2. For a preliminary design review (PDR)
(a) A written statement which either confirms that fracture
control is required or else provides a justification for not
implementing fracture control.
(b) Identification of fracture control-related project activities in
the fracture control plan including:
(1) Definition of the scope of planned fracture control
activities dependent upon the results of the hazard-
analysis and fracture control screening performed.
(2) Identification of low-risk fracture items.
(3) Identification of primary design requirements and
constraints which are affected by or affecting fracture
control implementation.
(c) Submission of the fracture control plan to the customer for
approval.
(d) Lists of potential fracture critical items and fracture critical
items in conformance with clause 6.4.2.
3. For a critical design review (CDR)
(a) A final fracture control plan which is approved by the
customer.
(b) Verification requirement
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