document title / titre du document TRP W ORK PLAN ... - emits - ESA

TRP Work Plan 2005-2007
Description of Activities
TEC-SB/7935/dc
12/Feb/09
TRP Reference:
T605-12MC
Improvement of force limited vibration testing methods for equipment/instrument unit
Title:
mechanical verification
The mechanical vibration testing approaches (sine and random) currently applied to satellite equipment / instrument units are
in general very conservative and might result to severe over-testing of the units compared to real flight environments. The
reasons for this are the different interface conditions applicable to the system and the test configuration (when the unit is
hard-mounted to the shaker table). Consequently these test approaches lead also to over-design of the units and therefore
significant mass penalties. Force limited vibration testing has been intensively investigated in NASA since many years. The
methods aim at establishing interface force estimates for the case when the unit is mounted on a flexible satellite support
structure rather than the shaker and to limit the test input for the unit test to these force estimates. The experiences in force
limited vibration testing are still very limited in Europe. Further investigations of this subject should increase the relevant
knowledge base and should contribute to the establishment of an ESA mechanical testing handbook covering the specific
aspects of force limited vibration testing. The objectives are to investigate the influence of the support structure mechanical
impedance on the random vibration environment and the execution of unit random vibration test on electro-dynamic shakers;
to identify relevant methods to more accurately derive the interface force limits (e.g. direct measurement at system level,
semi-empirical, analytical) and to assess their respective accuracy; to develop simplified but nevertheless adequate models
for the simulation of coupled system conditions; to verify the developed approaches by analytical and experimental means
(representative of existing equipment structures) and to establish the relevant input for the ESA Mechanical Testing
Handbook.
Deliverables:
Technical notes (incl. identification of methods to more accurately derive the interface force limits, models for the simulation of
coupled system conditions, verification of the developed approaches by analytical and experimental means).
Current TRL:
Target TRL:
Application Need/Date: TRL5 (operational method)
TRL2
TRL3
by 2008
Application/Mission: Engineering toolsapplicable to all S/C Contract Duration: 18 months
SW Clause : - Dossier0 Ref.: T-562
Consistency with Harmonisation
Roadmap and Conclusions:
TRP Reference:
Title:
T605-20MC
Advancement of Mechanical Verification Methods for non-linear spacecraft structures
For the purpose of spacecraft structure design development and verification by analysis the structures are in general a-priori
assumed to behave linear. Analytical predictions include static & dynamic analyses at satellite level but also launcher/satellite
coupled dynamic loads analyses (CLA) to predict flight loads for specific satellite configurations. However, experience has
shown that spacecraft structures can exhibit highly non-linear behaviour (e.g. due to backlash, joint gapping, rattling) and the
consequences of their dynamic effects can significantly affect the design verification procedures, in particular: to properly
evaluate flights loads with linearised models used in the CLA; the general performance of dynamic verification tests; to
demonstrate adequate coverage of non-linear dynamic effects in satellite verification tests. As a result, the presence of such
effects in spacecraft structures increases significantly the complexity of the mechanical verification process (analysis and
testing).The main objectives of this activity are: to review satellite design and verification test documentation in order to
identify relevant structure verification problems related to non-linear dynamic effects; to develop strategies for handling
non-linear dynamic effects within linear CLA models and to adequately convert the related CLA predictions into dynamic
verification test specifications; to analytically investigate the impact of spacecraft structure non-linearities on the verification
test performance (including non-linear dynamic effects resulting from e.g. shaker); to verify the proposed approaches with a
bread-board model (using available space hardware as far as possible); and to finally establish guidelines and
recommendations for the identification of potential structural non-linearities, the assessment of their effects and how to treat
them during the spacecraft structure design and development and the verification test phase.
Deliverables:
Documentation and breadboard.
Current TRL: TRL2 Target TRL: TRL3-4 Application Need/Date: TRL5 by 2010
Application/Mission: Engineering tools applicable to all S/C Contract Duration: 20 months
SW Clause : - Dossier0 Ref.: T-543
Consistency with Harmonisation
Roadmap and Conclusions:
Not directly linked to harmonised technology.
Page 206 of 227