CEN/TR 17603-32-26:2022

SLOVENSKI STANDARD
01-september-2022
Vesoljska tehnika - Priročnik za analizo mehanskih obremenitev vesoljskih plovil
Space engineering - Spacecraft mechanical loads analysis handbook
Raumfahrttechnik - Handbuch zur Analyse von mechanischen Lasten
Ingénierie spatiale - Manuel d’analyse des charges mécaniques pour vaisseaux spatiaux
Ta slovenski standard je istoveten z: CEN/TR 17603-32-26:2022
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.

TECHNICAL REPORT CEN/TR 17603-32-26

RAPPORT TECHNIQUE
TECHNISCHER BERICHT
June 2022
ICS 49.035; 49.140
English version
Space engineering - Spacecraft mechanical loads analysis
handbook
Ingénierie spatiale - Manuel d'analyse des charges Raumfahrttechnik - Handbuch zur Analyse von
mécaniques pour vaisseaux spatiaux mechanischen Lasten

This Technical Report was approved by CEN on 13 April 2022. It has been drawn up by the Technical Committee CEN/CLC/JTC 5.

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
© 2022 CEN/CENELEC All rights of exploitation in any form and by any means Ref. No. CEN/TR 17603-32-26:2022 E
reserved worldwide for CEN national Members and for
CENELEC Members.
Table of contents
European Foreword . 10
Preface. 11
1 Scope . 13
2 References . 14
3 Terms, definitions and abbreviated terms . 15
3.1 Terms from other documents . 15
3.2 Terms specific to the present document . 16
3.3 Abbreviated terms. 17
4 Overview of the loads analysis process . 21
4.1 Introduction . 21
4.2 Loads cycles . 22
4.3 Logic and sequence of loads analysis . 23
4.4 Loads and verification approach (prototype or protoflight) . 24
4.5 Loads and levels of assembly . 26
4.6 Mechanical loads for design and verification . 27
4.6.1 Spacecraft flight environments and dynamic loads . 27
4.6.2 Vibration environments and frequency range . 27
4.6.3 Introduction to analysis and test types for verifying mechanical
requirements . 28
4.6.4 Static and quasi-static loads . 30
4.6.5 Static loads test . 32
4.6.6 Spacecraft-launcher coupled loads analysis . 33
4.6.7 Sine vibration . 34
4.6.8 Spacecraft design loads and test predictions versus LV/SC CLA
results . 36
4.6.9 Random vibration and vibro-acoustic environment . 37
4.6.10 Shock testing . 39
4.7 Basic principles, criteria and assumptions in structure and loads verification . 40
4.7.1 Introduction . 40
4.7.2 Equivalence criteria for loads and environments . 40
4.7.3 Criteria for assessing verification loads . 42
4.7.4 Main inconsistencies of the loads verification process . 42
4.8 Notching in sine and random vibration testing . 43
4.8.1 Introduction . 43
4.8.2 Example of requirements . 44
4.8.3 Basic principles . 44
4.8.4 Response and force limiting . 45
4.8.5 Criteria for notching justification . 46
4.8.6 Conclusions on notching in sine and random vibration testing . 48
4.9 References . 49
5 Background on structural dynamics . 50
5.1 Introduction . 50
5.1.1 The dynamic environment . 50
5.1.2 Types of structural analysis . 51
5.1.3 List of topics . 51
5.1.4 Principal notations . 52
5.2 Dynamic environments – analysis and specifications . 54
5.2.1 Generalities . 54
5.2.2 Example - the maiden flight of Ariane 1 . 55
5.2.3 Sine environment . 57
5.2.4 Transient environment . 62
5.2.5 Random environment . 65
5.2.6 Sine-equivalent dynamics . 74
5.2.7 Combined environments . 83
5.3 Dynamic analysis . 86
5.3.1 Frequency domain analysis . 86
5.3.2 Modal approach . 88
5.3.3 Effective mass models . 92
5.3.4 Craig-Bampton models . 93
5.4 Coupled analysis and notching in sine tests. 107
5.4.1 FRF coupling . 107
5.4.2 Modal approach . 108
5.4.3 Simple example . 109
5.4.4 Use of the shock response spectrum . 111
5.5 Primary and secondary notching . 115
5.5.1 Modes concerned by primary notching . 115
5.5.2 Secondary notching . 115
5.5.3 Simple example . 116
5.5.4 Conclusions on notching in sine tests . 118
5.6 Random tests . 118
5.6.1 Issues on random tests . 118
5.6.2 Mechanical equivalence example . 119
5.6.3 Notching in random vibration tests . 121
5.7 Practical aspects of modal effective masses . 124
5.8 Conclusions . 126
5.9 References . 126
6 Launcher / spacecraft coupled loads analysis . 129
6.1 Introduction . 129
6.1.1 General aspects . 129
6.1.2 Launch loads and terminology used in the CLA process . 130
6.1.3 The role of the CLA within the loads cycle . 132
6.2 The phases of the CLA process . 133
6.2.1 Introduction . 133
6.2.2 Parameters driving the CLA process . 134
6.2.3 Mathematical model verification and database integration . 134
6.2.4 Finite element model reduction . 134
6.2.5 Checks on the Craig-Bampton matrices and OTM . 135
6.2.6 Frequency cut-off for computed modes . 135
6.2.7 Coupling of the launcher and spacecraft models . 135
6.2.8 Calculation of the generalized responses . 135
6.2.9 Determination of the physical responses . 135
6.2.10 Post-processing . 135
6.2.11 Uncertainty factors . 136
6.3 CLA output and results evaluation . 137
6.3.1 Overview . 137
6.3.2 Guidelines to response parameter selection. 138
6.3.3 Equivalent sine input . 138
6.3.4 Computation of static components from OTM . 138
6.3.5 Relative displacements . 139
6.3.6 Interface mechanical fluxes and overfluxes . 139
6.3.7 Results review, verification and validation . 144
6.3.8 Use of CLA results for structural verification . 145
6.3.9 Reporting . 145
6.4 Ariane 5 coupled loads analysis . 148
6.4.1 Introduction to Ariane 5 CLA . 148
6.4.2 Mission analysis organization and management . 149
6.4.3 CLA events and load cases . 150
6.4.4 Concomitant events and load cases combination . 159
6.4.5 Flight phases and CLA standard load cases . 160
6.4.6 Aspects of the Ariane 5 CLA methodology . 163
6.5 The Arianespace spacecraft qualification process . 165
6.5.1 Introduction . 165
6.5.2 Quasi-static loads . 166
6.5.3 Dynamic environment . 168
6.6 Space Shuttle coupled loads analysis . 174
6.6.1 Overview . 174
6.6.2 CLA load events . 175
6.6.3 Elements of the design and verification process for Space Shuttle
payloads . 176
6.7 References . 179
7 Static loads . 180
7.1 Introduction . 180
7.2 Quasi-static loads . 180
7.2.1 General aspects . 180
7.2.2 Equivalence between dynamic conditions and CoG net accelerations . 181
7.2.3 Quasi-static loads specification . 182
7.2.4 Prediction of QSL and mechanical environment by base-drive
analysis . 184
7.3 Static test philosophy and objectives . 184
7.4 Definition of static test configuration and load cases . 185
7.4.1 Introduction . 185
7.4.2 Boundary conditions . 186
7.4.3 Loading systems . 186
7.4.4 Load cases . 187
7.4.5 Instrumentation . 188
7.5 Static test evaluation . 188
7.6 References . 190
8 Sine vibration . 199
8.1 Introduction . 199
8.2 Sine vibration levels specification . 199
8.2.1 Sine loads for spacecraft . 199
8.2.2 Sine loads for payload and equipment . 200
8.3 Simulation / test prediction . 201
8.3.1 Introduction . 201
8.3.2 Boundary conditions . 201
8.3.3 Damping . 202
8.3.4 Notch assessment. 202
8.4 Sine vibration test . 203
8.4.1 Objectives . 203
8.4.2 Notching process . 204
8.4.3 Test preparation . 206
8.4.4 Sine test campaign. 219
8.5 References . 229
9 Random vibration and vibro-acoustics . 230
9.1 Introduction . 230
9.1.1 Overview . 230
9.1.2 Random vibration loads . 231
9.1.3 Vibro-acoustic loads . 231
9.2 Requirements . 234
9.3 Random vibration specification . 234
9.3.1 Introduction . 234
9.3.2 Component vibration environment predictor, Spann method . 234
9.3.3 Specifications derived from random and vibro-acoustic test data . 236
9.3.4 VibroSpec . 238
9.3.5 Test/analysis extrapolation method . 240
9.4 Random vibration analysis . 242
9.4.1 Finite element analysis and Miles’ equation . 242
9.4.2 Finite element analysis . 243
9.4.3 Guidelines for FE random vibration response analysis . 245
9.5 Random vibration testing . 247
9.5.1 Introduction . 247
9.5.2 Notching . 247
9.6 Vibro-acoustic analysis . 264
9.6.1 Introduction . 264
9.6.2 Boundary element analysis . 264
9.6.3 Statistical energy analysis . 267
9.6.4 General guidelines for vibro-acoustic analyses . 270
9.7 Acoustic testing . 272
9.7.1 Introduction . 272
9.7.2 Test plan/procedure . 272
9.8 Verification of compliance . 274
9.8.1 General aspects . 274
9.8.2 An example based on the vibration response spectrum . 275
9.9 Special topics in random vibration . 278
9.9.1 Simulation of the random time series . 278
9.9.2 Prediction of random acoustic vibration of equipment mounted on
panels . 281
9.9.3 Quick way to predict fatigue life (Steinberg method) . 285
9.10 References . 288
10 Shock . 291
10.1 Introduction . 291
10.2 Shock environment . 291
10.3 Shock design and verification process . 292
10.3.1 Shock input derivation to subsystems . 293
10.3.2 Shock verification approach . 294
10.3.3 Shock damage risk assessment . 297
10.4 References . 300
11 Dimensional stability . 301
11.1 Introduction . 301
11.2 Dimensional stability analysis . 302
11.2.1 Thermo-elastic distortion analysis . 303
11.2.2 1g-0g transition (gravity release) . 310
11.2.3 Moisture absorption / release . 311
11.3 Dimensional stability verification . 313
11.3.1 Introduction . 313
11.3.2 Thermal distortion test . 313
11.3.3 Gravity release test . 319
11.4 Material property characterisation testing . 320
11.4.1 Coefficient of Thermal Expansion (CTE) characterisation . 320
11.4.2 Coefficient of Moisture Expansion (CME) characterisation . 321
11.5 References . 322
12 Fatigue and fracture control . 323
12.1 Introduction . 323
12.2 Definitions . 326
12.3 List of events . 326
12.4 Load spectra per event . 330
12.4.1 General . 330
12.4.2 Existing load curves . 330
12.4.3 Measured load curves . 332
12.4.4 Calculating load curves . 334
12.5 Generation of fatigue spectra . 337
12.6 References . 339
13 Micro-gravity and micro-vibrations . 341
13.1 Introduction . 341
13.1.1 Background . 341
13.1.2 Scope. 342
13.2 Micro-gravity . 342
13.2.1 General aspects . 343
13.2.2 Derivation of micro-gravity specifications . 354
13.2.3 Micro-gravity environment verification . 362
13.3 Micro-vibration . 369
13.3.1 General aspects . 369
13.3.2 Micro-vibration analysis . 371
13.3.3 Micro-vibration budget assessment . 379
13.3.4 Pointing error synthesis . 382
13.3.5 Micro-vibration verification test . 383
13.4 Micro-gravity and micro-vibration disturbance sources . 387
13.4.1 Scope. 387
13.4.2 Review of potential disturbance sources . 387
13.4.3 Characterisation of the disturbance sources forcing functions . 398
13.5 References . 435
14 Soft stowed packaging . 437
14.1 Introduction . 437
14.2 Packaging guidelines . 438
14.3 Materials for packaging . 439
14.3.1 Physical properties . 439
14.3.2 Attenuation data for foam packed items . 445
14.4 Soft stowed equipment verification flow . 451
14.4.1 Hardware categories and criticality . 451
14.4.2 General verification aspects . 451
14.4.3 Off-the-shelf (OTS) items and already existing equipment . 456
14.4.4 New equipment / hardware . 458
14.2 References . 463
15 Nonlinear structures. 464
15.1 Introduction . 464
15.2 Common spacecraft structure nonlinearities . 464
15.2.2 Damping . 465
15.2.3 Contact . 466
15.2.4 Nonlinear stiffness. 467
15.3 Nonlinearity detection . 468
15.4 Handling of spacecraft structure nonlinearities . 469
15.4.1 Introduction . 469
15.4.2 Guidelines for testing . 470
15.4.3 Nonlinearity characterisation and parameter estimation . 472
15.4.4 Guidelines for structure modelling and analysis . 474
15.4.5 Impact of nonlinearities on CLA flight load predictions . 479
15.5 References . 481
16 Finite element models . 482
16.1 Introduction . 482
16.2 Requirements for structure mathematical models . 483
16.3 Introduction to V&V in computational mechanics . 483
16.4 Spacecraft finite element model complexity and validation test . 486
16.5 Uncertainty quantification during load cycles . 487
16.5.1 Overview . 487
16.5.2 Dynamic variability or uncertainty factor K . 487
v
16.5.3 Model factor K . 489
M
16.6 Verification and quality assurance for spacecraft finite element analysis . 489
16.7 Mathematical model validation . 491
16.7.1 General concepts and terminology . 491
16.7.2 Why a mathematical model validation process . 492
16.7.3 Categorization of the uncertainty and sources of disagreement
between simulation and experimental outcomes . 493
16.7.4 Specific aspects of the validation of spacecraft FEM for coupled loads
analysis . 493
16.7.5 Error localization and model updating by sensitivity and optimization . 498
16.7.6 Specific aspects concerning base-drive sine vibration testing and
“real-time” model validation . 499
16.7.7 Stochastic approaches for model validation . 500
16.8 References . 501

European Foreword
This document (CEN/TR 17603-32-26:2022) has been prepared by Technical Committee
CEN/CLC/JTC 5 “Space”, the secretariat of which is held by DIN.
It is highlighted that this technical report does not contain any requirement but only collection of data
or descriptions and guidelines about how to organize and perform the work in support of EN 16603-
32.
This Technical report (CEN/TR 17603-32-26:2022) originates from ECSS-E-HB-32-26A.
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 has been prepared under a mandate 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 TR covering the same scope but with a wider domain of applicability (e.g.: aerospace).
Preface
The “Spacecraft Mechanical Loads Analysis Handbook” has been developed with the aim to
harmonize methodologies, procedures and practices currently applied for the conduct of spacecraft
and payloads loads analysis. It makes available to the European Space Community a set of well
proven methods, procedures and guidelines for the prediction and assessment of structural design
loads and for the evaluation of the test loads. In particular, recent advances in the area of structural
dynamics and vibrations, in both methodology and performance, have the potential to make
spacecraft system analysis and testing more effective from technical, cost, and hardware safety points
of view. However, application of advanced analysis methods varies among the Space Agencies and
their contractors. Identification and refinement of the best of these methodologies and implementation
approaches has been an objective of the Working Group.
The handbook is intended to be a practical guide rather than a theoretical treatise. The emphasis is on
dynamic environments of spacecraft, however other mechanical environments are addressed and
often the principles are broad enough to be applicable in many cases to launch vehicles as well. It is
assumed that the reader has a general knowledge of spacecraft structures and structural dynamics
without necessarily being an expert in these disciplines.
This first edition represents a collection of contributions by a number of engineers from throughout
the European Space Community. It reflects the insight gained from their practical experience. The
contributions have been harmonised and the handbook completed by the “harmonization team”. The
level of treatment varies among topics, depending on the issues each author feels is critical and the
overall assessment performed by the harmonization team concerning the level of detail in each topic
that is important to the loads analysis process.
The book is not intended as a selfstanding textbook since in some cases it is rather complementary to
other ECSS documents and more in general to textbooks and publications on spacecraft structures and
structural dynamics. It can be a key tool for spacecraft designers, system and structural engineers who
need to find out more about mechanical loads analysis and for those in charge of developing
requirements and specifications.
The reader benefits best by reading the book sequentially, although most of the chapters are
selfcontained, with references to other parts of the book provided as needed. An overview of the
chapters is presented below:
• Chapter 4 gives an overview of the loads analysis process aimed at establishing appropriate
loads for design and testing.
• Chapter 5 presents a summary of the principles of structural dynamics addressed throughout
the different chapters of the present handbook.
• Chapter 6 addresses the launcher / spacecraft coupled loads analyses performed to check that a
spacecraft design is compliant with the overall mechanical environment generated by a
launcher during all flight phases and to ensure that the mission can be achieved.
• Chapters 7 to 10 deal with analysis and testing related to the various types of mechanical
environments generated by the launcher: static in chapter 7, sine vibrations in chapter 8,
random vibrations (including vibro-acoustic environment) in Chapter 9, shocks in chapter 10.
• Chapter 11 is devoted to dimensional stability i.e. the behaviour of highly accurate structures to
maintain their dimensions under all kinds of conditions.
• Chapter 12 deals with fracture control and fatigue life verification, discussing the various
aspects involved in deriving fatigue load spectra to perform analyses or tests.
• Chapter 13 addresses the micro-gravity and micro-vibration environment for which the
spacecraft systems should be designed and operated such that limit acceleration levels are not
exceeded.
• Chapter 14 is related to soft stowed equipment and the verification process of items packed in
foam, to assess the compatibility of the cargo item with the attenuated environments.
• Chapter 15 tackles the problems generated by a nonlinear behaviour of the structures, which
can significantly affect the verification process.
• Chapter 16 addresses the mathematical models used for loads analysis, with emphasis on finite
element analysis quality and acceptance of the results.

Funding and resources for the handbook were provided by the European Cooperation for Space
Standardization leading to the creation of the initial Working Group. However the number of
contributors soon increased with time and substantial additional volunteer support was provided by
individuals and organizations.
These additional resources have been crucial to the successful accomplishment of the “handbook
project”. All the volunteer contributors that have sacrificed their time are gratefully acknowledged, as
well as the contributors that made an effort beyond the allocated resources. This first edition of
handbook is thus the result of two and a half years of effort by the “enlarged” Loads Analysis
Working Group.
A substantial effort has been made to eliminate mathematical and factual errors. Nevertheless it is
possible (and likely) that some errors will be found through readers’ use of the handbook. Detected
errors along with any omissions, corrections or comments may be sent to either the ECSS Secretariat
or to the addresses below. If, as hoped, the book is of use to the space community, it could be updated
and made more useful and practical.
Scope
This document recommends engineering practices for European programs and projects. It may be
cited in contracts and program documents as a reference for guidance to meet specific
program/project needs and constraints.
The target users of this handbook are engineers involved in design, analysis and verification of
spacecraft and payloads in relation to general structural loads analysis issues. The current know-how
is documented in this handbook in order to make this expertise available to all European developers
of space systems.
It is a guidelines document; therefore it includes advisory information rather than requirements.
References
Due to the structure of the document, each chapter includes at its end the references called in it.

Terms, definitions and abbreviated terms
3.1 Terms from other documents
For the purpose of this document, the terms and definitions from ECSS-S-ST-00-01 apply.
For the purpose of this document, the following terms and definitions from ECSS-E-ST-32 apply:
buckling
design allowable
design factor
design limit load (DLL)
design load (DL)
design parameters
design ultimate load (DUL)
design ultimate stress
design yield load (DYL)
design yield stress
detrimental deformation
factor of safety (FOS)
failure
limit load (LL)
relieving loads
residual stress
stiffness
structural design
structure
ultimate strength
yield strength
For the purpose of this document, the following terms and definitions from ECSS-E-ST-32-10 apply:
local design factor (KLD)
margin policy factor (KMP)
model factor (KM)
project factor (KP)
test factors (KA and KQ)
ultimate design factor of safety (FOSU)
yield design factor of safety (FOSY)
3.2 Terms specific to the present document
3.2.1 Fundamental mode
Same as primary mode
3.2.2 Global mode
Mode which corresponds to a global movement
NOTE A global mode can be a secondary mode e.g. when opposed motion is present.
3.2.3 Load factor
Dimensionless multiple of the gravitational acceleration that represents the inertia force acting on a
structure
3.2.4 Local mode
Mode which corresponds to a local movement
NOTE A loca
...