THE OPTIMAL STRUCTURAL DESIGN OF QSAT FM (Flight Model)
Space System Dynamics Laboratory
M2 Takafumi ImazuFebruary 27, 2007
2007 Master thesis
2 / 20ContentsContents
BackgroundObjectiveMicro Satellites QSATRequirement for satelliteConfiguration of analysis modelStructural Design
– Structural Analysis– Structural Test
Conclusions QSAT (Qshu SATellite)
3 / 20BackgroundBackground
QSAT
Science InstrumentsScience Instruments plasma probe magnetometer
• Structure subsystem will be critical during launch by H-IIA rocket.
4 / 20ObjectiveObjective
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 / 20Micro satellite QSATMicro satellite QSAT
QSAT (Polar Plasma Observation Satellite)
OrbitSizeMass
MissionTerm
Depend H-IIA rocket≦ 500 mm Cube
≦ 50 kg
1 year
6 / 20
Directionz axis
x or y axis
Frequency>100Hz> 50Hz
Table.Stiffness Requirement
Requirement for SatelliteRequirement for Satellite
• Satellite Maximum size : 500×500×450mm3
Fig.Satellite Maximum Size
7 / 20Requirement for SatelliteRequirement for Satellite
PressureTension
z axis x or y axis-6G5G ± 5G
± 5G
Table Staic Load Acceleration
z axisx or y axis
5~100Hz5~100Hz
Table Dynamic Load AccelerationDirection Frequency Acceleration
2.5Go-p
2.0Go-p
20~200Hz200~2000Hz
Table Random vibration LevelFrequency range Power Spectral Density
+3dB/oct0.032
7.8GrmsRoot-Mean-Square value
8 / 20Configuration of analysis modelConfiguration of analysis model
①
②
③
③ ③
③
④
④ ④
④
⑤
Analysis model
i) Local partii) Whole satellite
Analysis
TopBottom
SideInsideFrange
Place Material Size (mm) Mass (kg)①②③④⑤
CFRP honeycombCFRP honeycombCFRP laminationCFRP lamination
Al5052
480× 480× 10480× 480× 10479× 180× 1314× 180× 2φ 225× 52
0.550.500.560.770.94
Angle & BoltsBus system
Al5052
Whole mass
1.499.9014.71
Table Element of analysis model
9 / 20Structural AnalysisStructural Analysis
Estimation of local part on analysis model
• CFRP Lam’s Side panel in itself where a unit is attached
f =π2 ρ h
D 1a2 + 1
b2( )i) formula
ii) Nastran (Structural analysis software)
CFRP : (Carbon Fiber Reinforced Plastic)Lam Lamination⇒
Member Element characteristics Characteristics of figureModel 1Model 2
UnitUnit
MassSHELL & Solid
PointQuad, Tria & Hexa
Table Analysis model
10 / 20Structural AnalysisStructural Analysis
(i) Model 1 (ii) Model 2
• Local side panel analyzed with Nastran
Magnetic torquer
Mass model Surface & Solid model
Analysis model
11 / 20Structural AnalysisStructural Analysis
Results
Fig. Each plates estimatedLocal plate of frequency ≥ 100Hz
Frequency of each plate is estimated
in whole satellite structure.
Platemd_2
Model 1 Model 2formulaFrequency
86.52 Hz 88.28 Hz90.62 Hz
Table Result of Frequency
Requirement
Not enough
12 / 20Structural AnalysisStructural Analysis
CFRP lamination plate in whole satellite structure
(i) Mass model (ii) Surface & Solid modelFig. Analysis model
Member Element Characteristic
UnitSURFACE
SOLIDor Mass
Table Analysis model
13 / 20Structural AnalysisStructural Analysis
Fig . Analysis model
(i) Mass model (ii) Surface & Solid model
(i) Mass model (ii) Surface & Solid model
Fig . Analysis model
Results
The requirement for stiffness is satisfied.
md_2Mass model Surface & Solid modelPlate
125.55 Hz123.09 Hz
FrequencyTable Frequency (local part)
Direction
x or y axis
Mass model Surface & Solid model
69.97 Hz65.23 Hzz axis 146.97 Hz153.99 Hz
Table Frequency (whole)
14 / 20
Table Strength (Mass)
L type Angle
Material Maximum stress6.3
Al5052Top & bottom panel 195 MPaHoneycomb
Allowable stress MS
195 MPa26.71 MPa37.00 MPa 4.3
L type Angle
Material Maximum stress6.4
Al5052Top & bottom panel 195 MPaHoneycomb
Allowable stress MS
195 MPa26.40 MPa66.06 MPa 2.0
Table Strength (Surface & Solid)
Structural AnalysisStructural Analysis
Static load analysisF : allowable stressS.F : margin of safety ratioσmax : stress of analysis
Requirement for H-IIA rocket is satisfied
MS: Margin of safety
MS =F
S.F×σ max- 1
15 / 20
Table Strength analysis
L type Angle
Material Maximum stress4.4
Al5052
Allowable stress MS
195 MPa37.03 MPa36.42 MPa
4.3①②①:Mass model②:Surface & Solid model
Structural AnalysisStructural Analysis
Sine vibration analysis
The satellite structure has no problem in analysis.
z axis
frequency range acceleration
5~100Hz 2.5G× 1.5
Table Requirement
16 / 20Structural testStructural test
Sine vibration test
When frequency is set 177.9Hz, sine vibration test is done with acceleration 0.1, 0.2 and 0.5G.
0.1
0.12
0.08
Acc
eler
atio
n(G
)
170.0 180.0 190.0Frequency (Hz)
177.9Hz 180.2Hz
Fig. frequency of satellite
Table Sweep test
Frequency range
Acceleration
Sweep velocity
100~300Hz
0.1G
4.0 octave/min
17 / 20Structural testStructural test
The analysis’s value is different from the test’s value.
The damping value with Nastran will be related
Comparing analysis with test
Unit
BatteryAttitude control
Camera 1
Top plate
2.5× 1.5GAnalysis
0.1G 0.2G 0.5GTest
1.100.970.37
1.76
0.64 0.91 1.411.00 1.00 1.081.36 1.56 1.89
5.46 3.30 4.15
Direction
YXZ
Z
Table Acceleration ratio
18 / 20
1e-7
1.0
1e-6
1e-5
1e-4
1e-3
0.01
0.1
20.0 100.0 1000.0
Pow
erS
pect
rum
Den
sity
(m/s
2 )/H
z
Frequency (Hz)Fig. result of random test
Structural testStructural test
Random test
19 / 20Structural testStructural test
Cause:Constraint for this panel is light.
rms (root mean square)
Unit
BatteryAttitude control
Camera 1
Top plate
Grms (base:0.078Grms)
0.4860.5461.544
2.618Sun sensor 1
Side plate
1.536
2.795
Direction
YX
ZZ
ZY
Table Acceleration ratio
20 / 20ConclusionsConclusions
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
Power supplyUnit
TNC
Sun sensor
Sun sensor
Fig. QSAT’s layout (preliminary version)
21 / 20
Thank you very much Thank you very much for your kind attentionfor your kind attention
ご清聴ありがとうございました
22 / 20
AppendixAppendix
23 / 20Micro satellites being developed in Kyushu Micro satellites being developed in Kyushu universityuniversity
QTEX QTEX-PR
Mission RequirementDemonstration of tether deployment
Tether is 2km length
Demonstration of bus units
This size is a half QTEX’s sizeMission
Orbit Altitude : 800km, Sun synchronized orbit
Size
Mass
less than 500×500×500 mm3
less than 50 kg less than 25 kg
MissionTerm 3 months 3 months
24 / 20Requirement for satelliteRequirement for satellite
Mass
Gravity point offset
Moment of inertia
Product of inertia
less than 50 kg
x, y ≦ 25 mm
z ≦ 250 mm
≦ 1 kgm2
≒ 0 kgm2
Table Characteristics of satellite
25 / 20Structural design of QTEX-PRStructural design of QTEX-PR
Based on old QTEX-PR, QTEX-PR was renewed.• Change of L angle’s design• Boring CFRP plate
Fig. QTEX-PR configuration
Fig. L angle type
26 / 20Micro Satellite QSATMicro Satellite QSAT
1) 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
Primary Objective
27 / 20Random vibration testRandom vibration test
Frequency of local part
Frequency of satellite
28 / 20Unit attached in satelliteUnit attached in satellite
Attitude controlGyro sensor
Electric power supplyBattery
Magnetic sensorCamera control
TNCCommunication instrument
MainCamera 1Camera 2
Sun sensor 1Sun sensor 2
Magnetic torquer 1Magnetic torquer 2Magnetic torquer 3
Boom
145,92,67145,92,67146,130,95146,92,68145,92,67145,92,67
141.5,92,110141.5,92,16145,92,67
40,60,4240,60,42
84,84,17284,84,172φ 10× 160φ 10× 160φ 10× 160
140,140,180
0.4100.4600.5000.9400.4100.4100.4500.3000.410
0.0300.030
0.9000.900
0.2500.250
0.250
3.000
(-82,-111.5,152)(12,-111.5,152)(111.5,10,152)(111.5,-85,152)(176,111.5,152)(-12,111.5,152)(-111.5,-10,152)
(-87,85,152)(-111.5,190,152)
(158,0,77)(0,158,77)
(197,-197,148)(-197,197,156)(-220,-200,152)
(-200,30,87)(-110,-200,87)
(0,0,123.5)
123456789
10111213141516
17
Unit Size (W,D,H mm) Mass (kg) Gravity Point (mm)
total mass 9.900 (kg)
29 / 20Unit attached in satelliteUnit attached in satellite
Fig. Equipment layout
30 / 20Sine wave vibrationSine wave vibration
31 / 20Random vibration testRandom vibration test