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Preliminary ANSYS Results: CCD Fixture and Lens Frame

Preliminary ANSYS Results: CCD Fixture and Lens Frame. Andrew Lambert. Outline. CCD Results Temperatures Deformations Conclusions Lens Frame Results Vertical Orientation Deformation Horizontal Orientation Deformation Deformation due to Thermal Expansion Conclusions. Thermal BC’s.

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Preliminary ANSYS Results: CCD Fixture and Lens Frame

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  1. Preliminary ANSYS Results:CCD Fixture and Lens Frame Andrew Lambert

  2. Outline • CCD Results • Temperatures • Deformations • Conclusions • Lens Frame Results • Vertical Orientation Deformation • Horizontal Orientation Deformation • Deformation due to Thermal Expansion • Conclusions

  3. Thermal BC’s • Radiation to 22 oC • Fixed Temperature of -120 oC on Focal Plane • Heat Flow of 110 mW at each corner • Heat Flow of 20 mW where Flex Strips attach

  4. Temperatures Invar Aluminum SiC

  5. Deformation of CCD Aluminum Invar SiC Note: Values in () indicates Moly spacer instead of Invar

  6. CCD Simulation Conclusions • Aluminum performs the worst in terms of stress and deformation • Invar and SiC have similar mechanical performance, however SiC has better thermal conduction and hence is better suited for cooling. • A ΔT of 20 K was the worst case scenario, and both Invar and SiC are better than this • Note: thermal contact points are modeled perfectly, which will not be the case in reality. • Overall, the best material for use is SiC, however; using Moly spacers with Invar greatly improves thermal conduction from the base to the CCD – makes it competitive with SiC • The best combination was a SiC focal plane with Moly spacers

  7. Structural BC’s • Fixed supports where frame attaches to focal plane • Standard Earth gravity

  8. Lens Frame - Vertical Note: The deformed lens shape is exaggerated! Titanium Invar

  9. Lens Frame - Horizontal Note: The deformed lens shape is exaggerated! Titanium Invar

  10. Thermal BC’s • Fixed Temperature of -120 oC where frame attaches to focal plane • Radiation to 22 oC • Radiation to -120 oC

  11. Thermal Expansion Titanium Invar

  12. Lens Frame Simulation Conclusions • The Titanium and S-LAH59 combination does not perform well structurally • If this combination is used, we need to “beef up” the lens frame considerably • S-LAH59 is much heavier than the Fused Silica • Invar36 and Fused Silica perform much better • Neither model has high stress – no failure modes • Invar36 and Fused Silica seem to be the best option going forward. • No matter which combination is used, I would recommend reinforcing the lens frame structure

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