SW.RS.EAU.SC - emits.sso.esa.intemits.sso.esa.int/.../SWARM_FEED_MODULE/SW.RS.EAU.SC.0002.pdfmodels shall be compatible with MSC/NASTRAN Version 2001r4 or NX/NASTRAN version 1.0.1

SW.RS.EAU.SC.0002Issue 1 June 2006

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EADS ASTRIUM Ltd 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.

SWARM FEM Requirement Spec.doc

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CONTENTS

1. INTRODUCTION...................................................................................................................................5 1.1. General..................................................................................................................................................5 1.2. Definition of Deliverables for Finite Element Mathematical Models......................................................5

2. APPLICABLE DOCUMENTS ........................................................................................................................5

3. GENERAL MODEL CONSTRUCTION REQUIREMENTS...........................................................................6 3.1. Co-ordinate Systems.............................................................................................................................6 3.2. Numbering systems ..............................................................................................................................7 3.3. Model Interfaces....................................................................................................................................7

4. MODEL CHECKING PROCEDURES...........................................................................................................7 Figure 1 SWARM Basic Co-ordinate System....................................................................................................6

APPENDIX GENERIC MECHANICAL FEM SPECIFICATION (ADS.E.0787)………………………...8 to 51


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1. INTRODUCTION

1.1. General

This document is written primarily to introduce the numbering system ranges for the various Finite Element Models (FEM)s for SWARM. This document supplements AD2(a) - which contains the first issue of the Generic Requirements for all EADS ASTRIUM (FEM)s. AD2(a) is also included as an Appendix in this document. During the design phase of SWARM, it is necessary to carry out static, dynamic and thermal distortion analyses of the spacecraft at regular intervals. These studies require system (spacecraft) level mathematical models of SWARM in its launch and in-orbit configurations. To enable the system level models to be generated and to aid the system level monitoring of the various instruments, appendages and structural subsystems, mathematical models of the constituent items are required. EADS ASTRIUM Ltd UK (EAU) is the initial point of contact for questions arising from this document.

1.2. Definition of Deliverables for Finite Element Mathematical Models

This specification defines the deliverable structural mathematical models required for analysis at system level and sets out the criteria for which such models need to be delivered. Finite element models - deliverable to system level, fall into the following categories

a. Static Models

b. Dynamic Models

All models must be accompanied by a document fully describing the model as defined in section 8.4 of AD2(a). For the structure subsystem (including attached Solar Arrays), Deployable Boom Assembly, Optical Bench and some equipment, full static and dynamic model deliveries will always be required for each major model variant. These models will be integrated and used for system level analysis and test predictions. These models should also be compatible with thermal distortion and stress analysis. Non-zero length rigid elements should therefore be avoided if possible as detailed in AD2(a). Note: If non-zero length rigid elements can be avoided, then it should be possible to provide a single FEM which can be used for static, dynamic and thermal distortion analyses. The full static and dynamic models of the items shall fully represent the items (structure/appendage) interface and will be used to ensure that the items interface integrity is maintained once mounted to the SWARM spacecraft structure. Reduced or simplified (spring/mass or beam/mass) models of some units/equipment shall only be supplied with prior agreement with the SWARM prime contractor (EAU).

2. APPLICABLE DOCUMENTS

(a) ADS.E.0787 Issue 1 Rev. 0 Generic Mechanical FEM Specification


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3. GENERAL MODEL CONSTRUCTION REQUIREMENTS

The general modelling rules and techniques to be included for all mathematical model deliveries – are defined in AD2(a). Analyses shall be performed using recognised finite element packages. All deliverable models shall be compatible with MSC/NASTRAN Version 2001r4 or NX/NASTRAN version 1.0.1 unless an alternative is agreed with EAU.

3.1. Co-ordinate Systems

The SWARM axis system is shown in Figure 1. All sub-models shall be created using local co-ordinate systems as described in section 4.4 of AD2(a).

Figure 1 SWARM Basic Co-ordinate System

These co-ordinate systems are to ensure that the entire sub-models can be moved as rigid bodies to correctly orientate and install them within the spacecraft system model. In order to achieve this aim ALL grids within a delivered model should ultimately be defined relative to a single co-ordinate system. Similarly the ‘output co-ordinate system’ for all grids in a deliverable model must reference a co-ordinate system defined internally within the model and NOT the default (Nastran system basic) co-ordinate system. Failure to adhere to this rule can mean that a ‘clean’ model can become over-constrained or contain internal mechanisms if the model is deployed, displaced or rotated as a rigid body by changing the definition of its reference co-ordinate system. Further co-ordinate systems may be required within the model and should be specified with respect to the individual item’s own basic co-ordinate system, NOT the Nastran default (system basic co-ordinate system).


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3.2. Numbering systems

The numbering systems to be used for all deliverable SWARM finite element models, regardless of the type of model being delivered, will comply with the following numbering system:

Item Sub-Models From To

1 System Integration (Reserved for use by Prime) 0 9999

2 Launch Vehicle Adaptor Frame 10000 29999

3 Basic Structure 30000 329999

4 Boom Support Structure 330000 349999

5 Tanks 350000 369999

6 Optical Bench 370000 399999

7 Boom Assembly 400000 429999

8 S-Band Antenna 430000 439999

9 Solar Arrays 440000 459999 The above numbering ranges are to be used for all NASTRAN cards, i.e. elements, grids, co-ordinate system IDs, property and material definitions etc., and the use of duplicate element numbers for elements of different types shall be avoided to enable full use of all available pre/post processing tools. It is suggested that the first 100 grids within the above number ranges are reserved for the interface grids for the item being considered. This will allow easy identification of all interface points for the item. Model sizes should be the smallest practicable in order to reduce overall model size for system level analysis. If further number ranges are required by items, these are to be justified and agreed in advance with EAU.

3.3. Model Interfaces

All model interfaces whether between the instruments/appendages and the SWARM satellite, or between the structural sub-systems shall be representative of the physical attachment points of the items and shall be modelled as independent points with six degrees of freedom. The interface points and co-ordinates to be used are to be agreed by the responsible party for both sides of the interface and EAU.

4. MODEL CHECKING PROCEDURES

The checks to be performed on all mathematical models prior to delivery - to ensure their correctness and applicability are defined in AD2(a).


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APPENDIX

GENERIC MECHANICAL FEM SPECIFICATION

(ADS.E.0787 issue 1 revision 0)


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DOCUMENT CHANGE DETAILS

ISSUE CHANGE AUTHORITY CLASS RELEVANT INFORMATION/INSTRUCTIONS

01 - - Initial Issue

DISTRIBUTION LIST

INTERNAL

EXTERNAL

I. Costello Marcus Faust (EAD) D. G. Graham Richard Belau (EAD) P. McMahon Hans Bestler (EAD) G. Wiggins ESA R. Baldwin A. Kiley R. Huie Configuration Management Library

Documents

SW.RS.EAU.SC - emits.sso.esa.intemits.sso.esa.int/.../SWARM_FEED_MODULE/SW.RS.EAU.SC.0002.pdfmodels shall be compatible with MSC/NASTRAN Version 2001r4 or NX/NASTRAN version 1.0.1