Brazilian Tunable Filter Imager (BTFI) Preliminary Design Review (PDR)?

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Brazilian Tunable Filter Imager(BTFI)Preliminary
Design Review (PDR)?
FEA Analysis Summary Version 1.0
USP-IAG Universidade de São Paulo 18-19th June
2008
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Mechanical Structure

• Compliant with Space Envelope
• Weight limit tbc through FEA analysis
• Current analysis is BTFI structure alone
• SAM with BTFI SIFS (or SAMI) loads
• Full FEA of SAM BTFI
• Modular structure
• Welded Al tubes with bolted connections
• Al plate covers
• Open structure to let the light through!
• Stiff bottom structure interface to SAM or ISB
  port

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Structural Model
Aluminium Plate
Aluminium Square Tube
Steel Shaft
Bottom Structure
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Loads(Assume Connection to Rigid Body at 10?C)
FPI (30kg)
Detectors (7.5kg) 0th 1st order
iBTF (19.5kg)
Cameras folds (3.2kg) 0th 1st Order
FPP (30kg)
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IR-Direct SAM port configurations(6
cardinal-point orientations)
SAM
ISB
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Flexure map(maximum flexure measures)
88.64µm
88.64µm
63.28µm
ISB
SAM
120.03µm
120.03µm
63.39µm
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1st significant eigen modes for complete structure
Frequency Hz Mode Shape Max displacement mm
1 59.258 Ty - Rx 4.18
2 71.058 Tx - Ry 6.27
3 116.046 Tz - Rz 6.97
4 116.556 Tx Tz - Rz 4.61
5 125.561 Tx - Tz 5.55
To quote Santoro Nothing to worry about.
Actually, the results show that the preliminary
mechanical structure is pretty stiff, thanks to
Rene's experience.
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Conclusions

• Fernando Santoro
• Bottom structure very stiff and can be light
  weighted
• Corner needs reinforcement design/FEA iteration
  recommended
• Gravity vector acts in most directions of
  instrument
• symmetric mechanical bottom structure recommended
  by adding A-struts
• When possible, a truss-like structural frame
  should be used
• extra weight compensated by reducing the
  thickness of some components
• Light-weighting of FP modules?
• Larger stainless steel rails, perhaps
• Rene KT
• Results quite encouraging
• Major flexure in direction of camera focus
• Very insensitive
• Major sensitivity is rotation of FPs (90µm
  tolerance)
• Structure performance within tolerance thicken
  FP rails to be sure?
• Real-life performance improved by inclusion of
  outer shell