the optimal structural design of qsat fm (flight model) space system dynamics laboratory m2 takafumi...

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