1. THE OPTIMAL STRUCTURAL DESIGN OF QSAT FM (Flight Model)
2007 Master thesis
THE OPTIMAL STRUCTURAL DESIGN OF QSAT FM (Flight Model)
Space System Dynamics Laboratory
M2 Takafumi Imazu
February 27, 2007

2. Contents Background Objective Micro Satellites QSAT
Requirement for satellite
Configuration of analysis model
Structural Design
Structural Analysis
Structural Test
Conclusions
QSAT (Qshu SATellite)

3. Background QSAT Science Instruments plasma probe magnetometer
Structure subsystem will be critical during launch by H-IIA rocket.

4. Optimal Structural Design of QSAT
Objective
Optimal Structural Design of QSAT
Based on QTEX-PR, the structural analysis and test are estimated.
Random vibration test is performed on QTEX-PR.
QTEX-PR (Qshu university Tether satellite EXperiments Public Relation)

5. QSAT (Polar Plasma Observation Satellite)
Micro satellite QSAT
QSAT (Polar Plasma Observation Satellite)

6. Requirement for Satellite
Satellite Maximum size : 500×500×450mm3

7. Requirement for Satellite

8. Configuration of analysis model
Local part
Whole satellite

9. Structural Analysis Estimation of local part on analysis model
CFRP Lam’s Side panel in itself where a unit is attached
CFRP : (Carbon Fiber Reinforced Plastic)
Lam ⇒ Lamination
i) formula
ii) Nastran (Structural analysis software)

10. Structural Analysis Analysis model Magnetic torquer
Local side panel analyzed with Nastran
Magnetic torquer
(i) Model 1
(ii) Model 2
Mass model
Surface & Solid model

11. Table Result of Frequency
Structural Analysis
Results
Table Result of Frequency
Not enough
Requirement
Local plate of frequency ≥ 100Hz
Fig. Each plates estimated
Frequency of each plate is estimated
in whole satellite structure.

12. Structural Analysis CFRP lamination plate in whole satellite structure
(i) Mass model
(ii) Surface & Solid model
Fig. Analysis model

13. Structural Analysis Results
(ii) Surface
& Solid model
(i) Mass model
Fig . Analysis model
The requirement for stiffness is satisfied.
(ii) Surface
& Solid model
(i) Mass model
Fig . Analysis model

14. Structural Analysis Static load analysis
F : allowable stress
S.F : margin of safety ratio
σmax : stress of analysis
MS: Margin of safety
Requirement for H-IIA rocket is satisfied

15. Structural Analysis Sine vibration analysis
The satellite structure has no problem in analysis.

16. Structural test Sine vibration test
When frequency is set 177.9Hz, sine vibration test is done with acceleration 0.1, 0.2 and 0.5G.

17. Structural test Comparing analysis with test
The analysis’s value is different from the test’s value.
The damping value with Nastran will be related

18. Structural test
Random test

19. Structural test Cause: Constraint for this panel is light.
rms (root mean square)
Cause:
Constraint for this panel is light.

20. Conclusions
Stiffness and strength of QTEX-PR have no problem in analysis.
It is difficult that each unit is attached in side panel of QTEX-PR.
About QSAT’s layout
Some measure for side panel must be formulated
Fig. QSAT’s layout (preliminary version)

21. Thank you very much for your kind attention
ご清聴ありがとうございました

22. Appendix

23. Micro satellites being developed in Kyushu university
QTEX
QTEX-PR
Mission Requirement
Demonstration of tether deployment
Tether is 2km length
Demonstration of bus units
This size is a half QTEX’s size
Mission
Orbit
Altitude : 800km, Sun synchronized orbit
Size
less than 500×500×500 mm3
Mass
less than 50 kg
less than 25 kg
Mission
Term
3 months
3 months

24. Requirement for satellite
Table Characteristics of satellite

25. Structural design of QTEX-PR
Based on old QTEX-PR, QTEX-PR was renewed.
Change of L angle’s design
Boring CFRP plate
Fig. L angle type
Fig. QTEX-PR configuration

26. Micro Satellite QSAT Primary Objective
To investigate plasma physics in the Earth’s aurora zone in order to better understand spacecraft charging
2) To conduct a comparison of FAC (Field-Aligned Current) observed in orbit with ground-based observation

27. Frequency of satellite
Random vibration test
Frequency of satellite
Frequency of local part

28. Unit attached in satellite
total mass (kg)

29. Unit attached in satellite
Fig. Equipment layout

30. Sine wave vibration

31. Random vibration test