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NuSTAR Critical Design Review Ae 105 June 5, 2008 California Institute of Technology

NuSTAR Critical Design Review Ae 105 June 5, 2008 California Institute of Technology. Structural/Thermal Elah Bozorg-Grayeli Elliott Pallett Matt Wierman Zac Lizer Alireza Moammad Karim Francisco Montero Chacon Vahe Gabuchian Dynamics/Control Silas Hilliard In Ki Choi

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NuSTAR Critical Design Review Ae 105 June 5, 2008 California Institute of Technology

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  1. NuSTAR Critical Design ReviewAe 105June 5, 2008California Institute of Technology Structural/Thermal ElahBozorg-Grayeli Elliott Pallett Matt Wierman ZacLizer AlirezaMoammadKarim Francisco Montero Chacon VaheGabuchian Dynamics/Control Silas Hilliard In KiChoi PrakharMehrotra Kevin Watts Derek Chan Metrology Nick Boechler Jason Damazo Manuel Fuentes David Gutschick 1

  2. Project Introduction • Project conducted as part of an 8 week interactive JPL-Caltech course • Performed analysis on multiple aspects of JPL flight project: NuSTAR 2

  3. NuSTAR Mission Overview • X-Ray Observatory • Obtain higher resolution images of X-Ray sources • Two hard X-Ray optics with 10 m focal lengths • 24 month mission (2) X-Ray Mirrors Mast & Canister (2) Focal Plane Modules Spacecraft Bus 3

  4. NuSTAR Description (2) X-Ray Mirrors S/C Bus 10.9 m Extendible Boom 4

  5. Chief Concern • X-Ray optics require precise pointing and alignment • Mirrors are mounted on end of extensible boom • Required accuracy of optics mandate determination of boom behavior 5

  6. JPL Level 1 Requirements 6

  7. Ae 105 Project Goals • Analyze the performance of NuSTAR observatory • Conduct structural and thermal analysis of the boom • Predict attitude and dynamics of the S/C • Design a metrology system to determine the position and orientation of the mirrors with respect to the bus • Assure JPL level 1 and below requirements are met 7

  8. Project Structure 8

  9. Structural/Thermal • Input: Disturbance forces estimated by dynamics • Output: Modal analysis results to dynamics and metrology 9

  10. Dynamics • Input: Frequencies from structures • Output: Forces to structures 10

  11. Metrology • Input: Frequencies from structures • Output: Metrology system to JPL 11

  12. Ae 105 Critical Design ReviewStructural/ThermalElah Bozorg-Grayeli, Francisco Montero Chacon, Vahe Gabuchian, Alireza Mohammad Karim,Zac Lizer, Elliott Pallett, Matt Wierman 12

  13. Introduction • Objectives • Timeline • Boom Description • CALFEM/ANSYS Verification • Cases (1-4) • Thermal Analysis • Deliverables • Conclusions 13

  14. Structural/Thermal Objectives • Goal: • Create a FEM model of the NuSTAR boom. • Determine static loading cases • Perform modal analysis on the model to determine natural frequencies. • Create an FD thermal model of the NuSTAR boom • Model shall be capable of determining temperatures based on loading conditions 14

  15. JPL Level 1 Requirements 15

  16. Boom Description 16

  17. Timeline of Approach • Establish material properties across all models • Developed independent CALFEM and ANSYS models • Developed FD thermal code • PDR • All RFAs accepted and answered by CDR work • Verified static and modal analysis from ANSYS with CALFEM

  18. CALFEM/ANSYS Verification • CALFEM – less capable, more open • ANSYS – more capable, less open • CALFEM will be used to verify results from ANSYS to establish ANSYS as a proper modeling package 18

  19. Case Types 19

  20. Case #1 • Same as JPL case used to characterize boom 20

  21. Bending – CALFEM 21

  22. Bending - ANSYS 22

  23. Axial Mode 23

  24. Torsion 24

  25. Case #1: Comparisons • Conclusion- CALFEM and ANSYS are internally consistent 25

  26. Case #2 26

  27. Case #2: Comparisons • Conclusion- CALFEM and ANSYS are internally consistent 27

  28. Case #3 28

  29. Case #3: Comparisons • Conclusion- CALFEM and ANSYS are internally consistent 29

  30. CALFEM/ANSYS Verification • ANSYS is verified as a modeling package for the NuSTAR boom • Based on results under multiple scenarios using CALFEM and ANSYS • CALFEM – less capable, more open • ANSYS – more capable, less open 30

  31. Case #4: ANSYS Modal Analysis 31

  32. Case #4: ANSYS - Bending 32

  33. Case #4: ANSYS - Elongation 33

  34. Case #4: ANSYS - Torsion 34

  35. Case #4: Modes 35

  36. Case Comparison • Modal frequencies vary as conditions are moved closer to flight parameters

  37. Thermal • Assumptions • Isothermal members • Ignores diagonal cables • No conduction between members or joints • Radiative coupling between members • Tilted at 10o away from Sun • All material properties measured at 298.15 K. • CTE-Al = 24 ppm/K • CTE-C = -1 ppm/K • Orbital period = 5700 s • Earth albedo = 0.3 • S/C coating • Absorptivity = 0.17 • Emissivity = 0.83 37

  38. Thermal Red - Insolated Black - Shaded 38

  39. Thermal 39

  40. Thermal • Assuming calibration at 298 K • Sunside: ∆x = 903 μm • Shadeside: ∆x = 861 μm • Across Boom ∆x = 42.6 μm ∆Θ = 182.6 μrad • Meets JPL Level 1 requirements 40

  41. Structural/Thermal Deliverables • To Dynamics • Moment of Inertia matrix • Stiffness matrix • Calculated natural frequencies • To Metrology • Deflections • Calculated natural frequencies • To JPL • CALFEM and ANSYS models of boom • ANSYS verified through CALFEM modeling • FD model of thermal loading of the boom • 3D Modal Mass matrix calculator for CALFEM library 41

  42. Conclusion • ANSYS is a verified static and modal analysis software for NuSTAR • Have created a more robust thermal and structural model of S/C flight conditions • Spacecraft meets level 1 structural/thermal requirements 42

  43. Recommendations • Characterize boom response under alternate conditions • “Test-as-you-fly” • Investigate control system interaction with ACS • Does cable prestress change with temperature?

  44. Ae 105Critical Design ReviewDynamics/ControlSilas Hilliard, In Ki Choi, Prakhar Mehrotra, Kevin Watts, Derek Chan 44

  45. Introduction • Task Overview • Requirements • System Level Interaction • Disturbance Modeling • Attitude Modeling • Integrated Model Results • Controllability • Open Issues and Concerns • Conclusion and Recommendation 45

  46. Task Overview • Create a dynamic model of the spacecraft • Account for the environmental disturbances • Evaluate the dynamic response of the spacecraft • Observe roll, pitch, yaw in time and frequency domains • Interface with the other teams to meet mission requirements 46

  47. JPL Level 1 Requirements 47

  48. Receivables • Project: • 300 microradian control • 120 microradian knowledge • Orbit description • Structures: • Moments of inertia for response • Modal frequencies for controller design • Metrology: • No supplemental requirements 48

  49. Deliverables • Project: • Coded model • PD controller • Structures: • Accelerations from torques • Controller frequencies • Metrology: • Performance of controller (long-term goal) • Relation of controllability to observability (long-term goal) 49

  50. Baseline Approach for Modeling Disturbances • Disturbances Modeled • Solar pressure, Atmospheric drag, and Earth’s oblateness • Formulation • AGI-Satellite Toolkit-3rd party software used to predict Keplerian Orbital parameters • Matlab used for • Independent verification of AGI-Satellite Toolkit results • Integration of the disturbance models with the rigid body dynamics 50

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