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Mechanical FEM Specification ExoMars Rover Module Sub-Systems

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    ExoMars Rover Vehicle   EXM.RM.RQM.ASU.0026 Issue A Page 1 of 25 Company Registration No. 2449259 Registered Office: Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2AS, UK getFile.jsp Mechanical FEM Specification ExoMars Rover Module Sub-Systems CI CODE: E131000000 DTI EXPORT CONTROL RATING: 9E001, 9E002, 9E004  Rated by: M. Roe This document is produced under ESA contract 19234/05/NL/CB, ESA export exemptions may therefore apply. These Technologies may require an export licence if exported from the EU Prepared by: Date: J. Michelin Checked by: Date: A. Kiley Approved by: Date: J. Clemmet Authorised by: Date: M. Roe  © Astrium Limited 2010 Astrium Limited owns the copyright of this document which is supplied in confidence and which shall not be used for any purpose other than that for which it is supplied and shall not in whole or in part be reproduced, copied, or communicated to any person without written permission from the owner. Astrium Limited Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2AS, England    ExoMars Rover Vehicle   EXM.RM.RQM.ASU.0026 Issue A Page 2 of 25 Astrium Limited owns the copyright of this document which is supplied in confidence and which shall not be used for any purpose other than that for which it is supplied and shall not in whole or in part be reproduced, copied, or communicated to any person without written permission from the owner. getFile.jsp INTENTIONALLY BLANK    ExoMars Rover Vehicle   EXM.RM.RQM.ASU.0026 Issue A Page 3 of 25 Astrium Limited owns the copyright of this document which is supplied in confidence and which shall not be used for any purpose other than that for which it is supplied and shall not in whole or in part be reproduced, copied, or communicated to any person without written permission from the owner. getFile.jsp CONTENTS 1. INTRODUCTION...........................................................................................................................................6   2. ABBREVIATIONS AND ACRONYMS...........................................................................................................6   3. MODEL DATA AND IDENTIFICATION.........................................................................................................7   3.1 GENERAL INFORMATION....................................................................................................................7   3.1.1 Deployed/Stowed configuration...................................................................................................7   3.1.2 Model identification.......................................................................................................................7   3.1.3 Linearity of the model...................................................................................................................7   3.1.4 Version of NASTRAN software....................................................................................................7   3.1.5 Model units...................................................................................................................................7   3.2 BOUNDARY CONDITIONS...................................................................................................................7   3.2.1 Interface node label......................................................................................................................7   3.2.2 Internal interfaces/joints...............................................................................................................8   3.3 NUMBERING RANGE............................................................................................................................8   3.3.1 Bulk data card numbering range..................................................................................................8   3.3.2 Bulk data duplicate card...............................................................................................................8   3.3.3 Continuation card.........................................................................................................................8   3.3.4 FEM size......................................................................................................................................8   3.4 COORDINATE SYSTEM........................................................................................................................9   3.4.1 Reference system........................................................................................................................9   3.4.2 Local reference system................................................................................................................9   3.4.3 Deployable item systems.............................................................................................................9   3.4.4 Cards referring to reference system.............................................................................................9   3.5 NASTRAN PARAMETERS..................................................................................................................10   3.5.1 Prohibited NASTRAN parameters..............................................................................................10   3.5.2 Required NASTRAN parameters...............................................................................................10   3.5.3 AUTOSPC parameter.................................................................................................................10   3.5.4 Parameters affecting a set of data.............................................................................................10   3.6 PERMITTED AND PROHIBITED CARDS...........................................................................................11   3.6.1 Permitted NASTRAN card..........................................................................................................11   3.6.2 Prohibited NASTRAN card.........................................................................................................11   3.7 NODES AND ELEMENTS....................................................................................................................11   3.7.1 Free nodes.................................................................................................................................11   3.7.2 Nodes connecting CELAS..........................................................................................................11   3.7.3 Spring elements.........................................................................................................................12   3.8 PROPERTIES......................................................................................................................................12   3.8.1 Material orientation.....................................................................................................................12   3.8.2 E, G and  ν  relation.....................................................................................................................12   3.8.3 Bar element orientation..............................................................................................................12   3.8.4 Model mass definition................................................................................................................12   3.8.5 Structural mass distribution........................................................................................................12   3.8.6 Non-structural mass distribution.................................................................................................12   3.9 THERMAL............................................................................................................................................13   3.9.1 Model thermo elastic properties.................................................................................................13   3.10 DAMPING...........................................................................................................................................13   3.10.1 Prohibited damping definition...................................................................................................13   3.10.2 Recommended damping definition...........................................................................................13   3.10.3 Symmetry of the damping matrix.............................................................................................13   4. CHECKS......................................................................................................................................................14   4.1 GEOMETRY CHECKS.........................................................................................................................14   4.1.1 Free boundaries.........................................................................................................................14      ExoMars Rover Vehicle   EXM.RM.RQM.ASU.0026 Issue A Page 4 of 25 Astrium Limited owns the copyright of this document which is supplied in confidence and which shall not be used for any purpose other than that for which it is supplied and shall not in whole or in part be reproduced, copied, or communicated to any person without written permission from the owner. getFile.jsp 4.1.2 Coincident nodes........................................................................................................................14   4.1.3 Element geometry......................................................................................................................14   4.1.4 Skew...........................................................................................................................................14   4.1.5 Taper..........................................................................................................................................14   4.1.6 Aspect ratio................................................................................................................................14   4.1.7 Warp...........................................................................................................................................14   4.1.8 Element co-ordinate systems.....................................................................................................14   4.1.9 Coincident elements...................................................................................................................15   4.2 BOUNDARY CONDITIONS.................................................................................................................15   4.2.1 Magnitude of seismic mass........................................................................................................15   4.2.2 Magnitude of interface load CELAS...........................................................................................16   4.3 MODEL CONDITIONING CHECKS.....................................................................................................16   4.3.1 Over constraint check.................................................................................................................16   4.3.2 Diagonal terms of stiffness matrix..............................................................................................17   4.3.3 DFLR check................................................................................................................................17   4.3.4 Warning messages.....................................................................................................................17   4.3.5 Maxratio......................................................................................................................................17   4.4 FREE-FREE MODES...........................................................................................................................18   4.4.1 Number of free/free modes........................................................................................................18   4.4.2 Frequencies of rigid body modes...............................................................................................18   4.4.3 SUPORT strain energy..............................................................................................................18   4.5 MASS PROPERTIES...........................................................................................................................18   4.5.1 Mass according to axes.............................................................................................................18   4.5.2 Mass matrix at G, N, F and A set size........................................................................................18   4.5.3 Centre of gravity.........................................................................................................................18   4.6 STATIC LOAD CHECKS......................................................................................................................19   4.6.1 Force balance.............................................................................................................................19   4.6.2 Enforced unit displacement and rotation....................................................................................19   4.6.3 Epsilon error ratio.......................................................................................................................19   4.6.4 Elements with zero load.............................................................................................................19   4.6.5 Magnitude of SPCFORCE at grids constrained by AUTOSPC.................................................19   4.7 DYNAMIC CHECKS.............................................................................................................................20   4.7.1 Low frequency acceleration.......................................................................................................20   4.8 SIMPLIFIED MODEL............................................................................................................................20   4.8.1 Simplified model accuracy.........................................................................................................20   4.9 THERMAL CHECKS............................................................................................................................20   4.9.1 Reference temperature check....................................................................................................20   4.9.2 Thermo elastic analysis suitability checks.................................................................................20   5. ACCURACY OF FEM VERSUS HARDWARE............................................................................................21   5.1.1 Mass, inertia and centre of gravity accuracy..............................................................................21   5.1.2 Dynamic accuracy......................................................................................................................21   6. DELIVERABLES..........................................................................................................................................22   6.1 FILES DELIVERED..............................................................................................................................22   6.1.1 Type of delivered files................................................................................................................22   6.1.2 Format of delivered files.............................................................................................................22   6.1.3 Files identification.......................................................................................................................22   6.2 NASTRAN INPUT FILES.....................................................................................................................22   6.2.1 NASTRAN input files..................................................................................................................22   6.2.2 Use of ALTER............................................................................................................................22   6.2.3 NASTRAN version......................................................................................................................22   6.3 NASTRAN BULK DATA.......................................................................................................................22   6.3.1 Use of PARAM...........................................................................................................................22   6.3.2 NASTRAN files for thermo elastic model...................................................................................22   6.4 ANALYSIS RESULTS..........................................................................................................................22   6.4.1 Model check results....................................................................................................................22  
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