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

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

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

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)

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

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

Requirement for Satellite

Configuration of analysis model Local part Whole satellite

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)

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

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.

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

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

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

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

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.

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

Structural test Random test

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

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)

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

Appendix

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

Requirement for satellite Table Characteristics of satellite

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

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

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

Unit attached in satellite total mass 9.900 (kg)

Unit attached in satellite Fig. Equipment layout

Sine wave vibration

Random vibration test