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衛星搭載機器構造設計と振動試験金田英宏（素粒子宇宙物理学専攻 Uir研）

ChubuSat Workshop

AKARI telescope with SiC mirrors

Ouch!

Z-axis random 0 dB （7 Grms)

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Ouch!

Thickening CVD coating：primary mirror 8 kg ⇒ 11 kg

porous SiC machining

CVD coatinggrindingpolishing

Random vibration levels: Z-axis

7.0 Grms

PSD

(G2 /H

z)

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Launching vibrations

Main Engine Cut-Off・Quasi-static・Shock

Lift-Off・Random・Acoustic

Typical lateral eigen-frequency15 Hz 30 Hz 40 Hz 120 Hz

Component

Sub-System

System

Rocket

Finite Element Method (FEM) Analysis

Mass: 42.75 kg (Jig) + 20.8 kg (test)Longitudinal shift: 138.2 Hz (fundamental)

Software: NASTRAN, ANSYS, , , SolidWorks

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Mechanical Design (1)

MS (Margins of Safety) = σallowable/(σmaxx SF) – 1SiC: σallowable = 270 MPaTitanium: σyield = 827 MPa, σultimate = 890 MPaceramic: SF = 2.5, metal: SF = 1.1 – 1.3

・High Reliability (高信頼性)

critical damping

damping factor

Damping ratio

mass damping structural damping

Diagonal matrix

Mechanical Design (1)

MS (Margins of Safety) = σallowable/(σmaxx SF) – 1SiC: σallowable = 270 MPaTitanium: σyield = 827 MPa, σultimate = 890 MPaceramic: SF = 2.5, metal: SF = 1.1 – 1.3

・High Reliability (高信頼性)

critical damping

damping factor

Damping ratio

mass damping structural damping

Diagonal matrix

Von Mises stress (scalar)

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Transfer function (Bode plot)

Gain 応答倍率20 x Log G

Magnitude(dB)

Phase(deg)

Mechanical Design (2)・Lightweight (低質量) ⇔ ・High Stiffness（高剛性）

A

lx

w

ρ: density

moment of inertia of area(断面2次モーメント)

Eigen-frequency(latitudinal)λ= 1.87 (fixed-free)

3.14 （両端支持）4.73 （両端固定）

Eigen-frequency(longitudinal)

a

Young’s modulus（縦弾性係数）

σ: stressε: strain

y

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Typical test flow

QT (qualification test認定試験)

0. Jig test Setup of jigs, accelerometers (“pick-up”) for control Settings of vibration levels

Setup of test instrument, accelerometers & strain gauges for measurement

Transfer function, eigen-frequency, Q value

Same flow for each of X-, Y- Z-axis tests

1. Modal 2. 1/4 random3. Modal4. 1/2 random5. Modal6. 1/1 random (QT)7. Modal

8. 1/4 shock9. Modal10. 1/2 shock11. Modal12. 1/1 shock (QT)13. Modal

Settings of shock wave parameters (half-sine)

2nd vibration test & shock test

Passed z-axis random 0 dB （7 Grms）and shock 0 dB （29 G) tests

Three sets of primary/secondary mirrors fabricated:(1) MTM, (2) FM, (3) backup

New MTM primary / telescope

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Random vibration test of FM telescope assembly

No misalignment due to vibration

Before vibration+2.39λ

-1.40λ

After vibration+2.05λ

-1.40λ

426 nm RMS 408 nm RMS

Cryogenic optical testing of AKARI telescope

Interferometer

Telescope

750φflat

LaserReference

Principle of interferometric measurement

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Cryogenic vibration testInterferometric fringe pattern Mirror tilted!

Mirror support structure

Cryogenic vibration testInterferometric fringe pattern Mirror tilted!

Mirror support structure

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FEM analysis of SPICA telescope (by ASTRIUM)

ASTRO-E HXD (1996-1997)

Frequency

Y-axis (lateral):160 Hz (predicted)

~60 Hz (measured)

10 Hz 100 Hz 1000 Hz

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ASTRO-E HXD (1996-1997)

BGO scintillator (Main)

BGO scintillator (Anti)

CFRP

CFRP

σmax vs. CFRP plate position

SolidWorks理学装置開発室が所有

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FEM analysis for SPICA instrument with SolidWorks

Requirements: Mass < 20 kg (incl. 20 %), Stiffness > 150 Hz ⇒ Model: 15.9 kg, 205 Hz

Summary・ Mechanical design for satellite-borne instruments:

(1) High reliability(2) Lightweight(3) High stiffness

⇔ requirements on mass and eigen-frequency

・ Model prediction by FEM: eigen-frequencies, maximal stress

⇔ Measurement by vibration testeigen-frequencies, Q-values