T. Basset, J.P Dudon ALCATEL SPACE

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1 APPLICATION OF CORATHERM TO SPACECRAFT THERMO-ELASTICITY ANALYSIS T. Basset, J.P Dudon ALCATEL SPACE 15th ESA Workshop page 1/12-09/10/01 Summary 1 About CORATHERM capabilities 2 - Developments dedicated to Thermo-elasticity (T-E) analysis 3 - Validation of the developments : New method for the computation of thermo-elastic deformations on spacecraft panels. 15th ESA Workshop page 2/12-09/10/01

2 Thermal Model nodes for panels : Structure nodes : averaged temperature Unit nodes : isothermal nodes Out of Model nodes : 1- CORATHERM capabilities Elementary conductive nodes : automatically generated and eliminated Partial nodes : Local thermal information within nodes UNIT node n 4 UNIT node n 5 Panel Structure Elementary Nodes UNIT node n 4 Structure Nodes 1, 2 and 3 UNIT node n 5 Partial Node of Structure Node 2 STEP 1 STEP 2 Partial Node of Unit Node 5 15th ESA Workshop page 3/12-09/10/ Development dedicated to T-E application Objective : Accurate evaluation of the structure deformations under effect of thermal gradients In-house development of specific tools Main development : Automated interface PATRAN/ CORATHERM/ NASTRAN specifically dedicated to mechanical engineers for improving T-E analysis T UP Specific Thermal Meshing (Upside panel) T DOWN Mechanical Meshing (Neutral fiber) Specific Thermal Meshing (Downside panel) 15th ESA Workshop page 4/12-09/10/01

Development dedicated to T-E application Technical and Industrial Objectives : Increasing accuracy Saving time Increasing reliability Main requirements :

data exchange between both domains 15th ESA Workshop page 5/12-09/10/01 Development dedicated to T-E application Pre-processing 3- Final thermal model

3 Development dedicated to T-E application Technical and Industrial Objectives : Increasing accuracy Saving time Increasing reliability Main requirements : Keep advantages of both thermal (CORATERM) and mechanical (NASTRAN) framework Does not increase the Thermal engineer s work Allows rapid and optimised data exchange between both domains 15th ESA Workshop page 5/12-09/10/01 Development dedicated to T-E application Pre-processing 3- Final thermal model (up) 1- EF mechanical mesh Mixing 2- Classical thermal meshing (nodal) Preserved Thermal Model nodes Created Partial nodes 15th ESA Workshop page 6/12-09/10/01

4 Development dedicated to T-E application Temperature computation On classical thermal model nodes (Equivalent Temp.) On partial nodes (Local Temp.) in a recalculation process Using a physically consistent method (Equivale) For steady and transient cases Interface toward NASTRAN Affectation of local temperatures to the corresponding mechanical nodes (EF terminology) Generation of NASTRAN format temperature file 15th ESA Workshop page 7/12-09/10/ Application to T-E Computation Thermo-elasticity is a linear phenomenon Separation between : Structural behaviour (M SENS ) Thermal behaviour (variation of temperature) Classical computation method CORATHERM provides classical thermal inputs Rough thermal mapping in PATRAN NASTRAN computes Thermo Elastic deformations Limited to steady state computation Current method (new) X T j Y T j Z T j = M X R j Y R j Z R j CORATHERM NG provides accurate and detailed thermal inputs Transient effects are still ignored SENS T T... T 15th ESA Workshop page 8/12-09/10/ N

Application to T-E Computation Application to a Telecommunication Satellite PATRAN thermal inputs from CORATHERM NG 15th ESA Workshop page 9/12-09/10/01 Application to T-E Computation The MSENS

5 Application to T-E Computation Application to a Telecommunication Satellite PATRAN thermal inputs from CORATHERM NG 15th ESA Workshop page 9/12-09/10/01 Application to T-E Computation The MSENS concept (in study) Use of linear aspects of Thermo-Elasticity θ = M * T SENS T Element_1 θ = MSENS Element_1 MSENS Element_2 * T Element_2 θ = MSENS Element_1 * T Element_1 + MSENS Element_2 * T Element_2 [ ( ] )( ) T jx Y T j T1 Z T T j 2 X = M SENS... R j RY TN j R Z j CORATHERM NASTRAN Accurate thermal mapping is provided by CORATHERM MSENS is computed using NASTRAN (pre-treatment) for a given instant Applicable to transient calculations 15th ESA Workshop page 10/12-09/10/01

Application to T-E Computation Application to Jason Model : deformations of 15 DOF radians out of eclipse eclipse out of eclipse secondes High accuracy of the results avoid over or sub-sizing Better

6 Application to T-E Computation Application to Jason Model : deformations of 15 DOF radians out of eclipse eclipse out of eclipse secondes High accuracy of the results avoid over or sub-sizing Better understanding of the phenomenon with the transient behaviour determination of realistic sizing cases 15th ESA Workshop page 11/12-09/10/ Conclusions Validation of a new methodology to compute T-E deformations Optimisation of Thermal ( T) and Mechanical (M SENS ) analyst`s know-how New possibility to Compute accurate thermal mapping on honeycomb panels Prevents from abusive approximations Direct impacts on pointing budget Automated procedures are now validated Transient results are provided Better understanding of the phenomenon 15th ESA Workshop page 12/12-09/10/01

Appendix U. Evaluation of stochastic & statistic methods for spacecraft thermal analysis. Jean-Paul Dudon (Thales Alenia Space, France)

Appendix U. Evaluation of stochastic & statistic methods for spacecraft thermal analysis. Jean-Paul Dudon (Thales Alenia Space, France) 319 Appendix U Evaluation of stochastic & statistic methods for spacecraft thermal analysis Jean-Paul Dudon (Thales Alenia Space, France) Hélène-Marie Pasquier (CNES, France) 320 Evaluation of stochastic