1 / 27

Hexapod Detector Mounts

Hexapod Detector Mounts. B. C. Bigelow, UM Physics 3/24/05. Hexapod Detector Mounts. Motivations: Provide a common mount design for Vis and IR detectors Minimize detector package SS thermal stresses Minimize detector package SS temperature gradients

kalliyan
Download Presentation

Hexapod Detector Mounts

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Hexapod Detector Mounts B. C. Bigelow, UM Physics 3/24/05 Bruce C. Bigelow -- UM Physics

  2. Hexapod Detector Mounts Motivations: • Provide a common mount design for Vis and IR detectors • Minimize detector package SS thermal stresses • Minimize detector package SS temperature gradients • Accommodate various detector package materials (Invar, TZM) • Accommodate various FPA baseplate materials (TZM, SiC, ?) • Accommodate local detector PCBs, connectors, heaters, etc. • Minimize weight, maximize first resonance Bruce C. Bigelow -- UM Physics

  3. Hexapod Detector Mounts Detector space frame! – but fabrication unfriendly… Bruce C. Bigelow -- UM Physics

  4. Hexapod Detector Mounts A fabrication-friendly version… Bruce C. Bigelow -- UM Physics

  5. Hexapod Detector Mounts Fabrication options for hexapod: • Fabrication method may depend on hexapod material choice • Powder metallurgy methods (HIP, laser sintering) • Abrasive water-jet cutting • Laser cutting • Plunging and/or wire EDM • Stress-relieve rough blanks prior to cutting • Polish blanks flat and parallel prior to cutting • Final grind/polish mounting pads to spec. after cutting • Other? Bruce C. Bigelow -- UM Physics

  6. Hexapod Detector Mounts Bruce C. Bigelow -- UM Physics

  7. Hexapod Detector Mounts Arbitrary mount height of 12mm – can be lower Bruce C. Bigelow -- UM Physics

  8. Hexapod Detector Mounts Bruce C. Bigelow -- UM Physics

  9. Hexapod Detector Mounts Bruce C. Bigelow -- UM Physics

  10. Hexapod Detector Mounts Bruce C. Bigelow -- UM Physics

  11. Finite Element Analyses Quantify performance via FE analyses : • Hexapod flexures are 1mm wide x 3mm high (all cases) • Hexapod material is TZM (Invar another option) • Static analyses: 100g deflections and stresses • Dynamic analyses: first 10 frequencies and mode shapes • Steady-state thermal: stress for -150K temp excursions • Steady-state thermal: heat flow and temperature gradients • Summary follows individual results Bruce C. Bigelow -- UM Physics

  12. Focal Plane Material Properties Room temp. material properties Bruce C. Bigelow -- UM Physics

  13. FEA - static Static FEA: • 100g accelerations, Gx, Gy, Gz • Det. package base models only, no AlN, MCT, epoxy, etc. • Two material combinations – Invar/TZM, and TZM/TZM • Simplified model of hexapod mount (no “pads”) • Max deflections: 1.5 - 1.9 microns • Max stresses: 20 - 26 MPa (Invar/TZM) • Invar yield = 300 MPa • TZM yield = 860 Mpa • Low stress in package material - max. 20 Mpa (point load) Bruce C. Bigelow -- UM Physics

  14. FEA - static Deflections in meters, 1.4 microns max. Gz, Z-axis deflections – 1.4 microns max Bruce C. Bigelow -- UM Physics

  15. FEA - static Stress in Pa, 26 MPa max., (point loads) Gz, Z-axis deflections – 1.4 microns max Bruce C. Bigelow -- UM Physics

  16. FEA - dynamic Dynamic FEA: • Det. package base models only, no AlN, Si, MCT, epoxy, etc. • Two material combinations – Invar/TZM, and TZM/TZM • Simplified model of TZM hexapod mount • First resonances: • TZM/invar – 3000 Hz • TZM/TZM – 3053 Hz Bruce C. Bigelow -- UM Physics

  17. FEA - dynamic Gz, Z-axis deflections – 1.4 microns max Bruce C. Bigelow -- UM Physics

  18. FEA – steady state thermal Steady-state thermal stress: • Minus 150 K temperature excursion • Baseplate, hexapod mount, and package base • Four material combinations for baseplate and package: • TZM/Invar, TZM/TZM, SiC/TZM, SiC/Invar • Simplified model of hexapod mount (no “pads”) • Deflections: 6.9 – 8.7 microns (TZM/TZM, TZM/Invar) • Deflections: 7.9 - 9.7 microns (SiC/Invar, SiC/TZM) • Pkg stresses: 2.3 Mpa (TZM/Invar) • Pkg stresses: 1.1 - 1.7 Mpa (SiC/TZM, SiC/Invar) Bruce C. Bigelow -- UM Physics

  19. FEA – steady state thermal Elements Gz, Z-axis deflections – 1.4 microns max Bruce C. Bigelow -- UM Physics

  20. FEA – steady state thermal Stress in Pa, 14.8 MPa max. (point loads) Bruce C. Bigelow -- UM Physics

  21. FEA – steady state thermal Steady-state heat flow: • Baseplate, hexapod mount, and package base • 200 mW heat load imposed on top surface of package • Baseplate – back side sunk to a cold source at 140 K • Four material combinations for baseplate and package: • TZM/Invar, TZM/TZM, SiC/TZM, SiC/Invar • Simplified model of TZM hexapod mount (no “pads”) • Max. temp variation: 0.56 K (TZM/Invar) • Min. temp variation: 0.05 K (SiC/TZM and TZM/TZM) • Min final temp: 142.3 K (SiC/TZM) • Max final temp: 144.6 K (TZM/Invar) Bruce C. Bigelow -- UM Physics

  22. FEA – steady state thermal Boundary cond. Bruce C. Bigelow -- UM Physics

  23. FEA – steady state thermal Temp variations (K) – SiC/TZM Bruce C. Bigelow -- UM Physics

  24. FEA summary deflections, u, in microns Bruce C. Bigelow -- UM Physics

  25. Detector mount taxonomy Yale flex LBL flex UM flex UM hexapod Bruce C. Bigelow -- UM Physics

  26. Detector mount comparison Bruce C. Bigelow -- UM Physics

  27. Hexapod Detector Mounts Conclusions: • Hexapod mount kinematically connects detectors to focal plane: • Low thermal stress for -150 K temperature change • Large conduction cross-section minimizes thermal gradients • Common mount design works for both NIR and VIS detector packages • Very low thermal stresses in base plate, mount, and packages • Hexapod provides “optimal” support for detectors: • Minimum mass, maximum stiffness solution • Very high first resonance – 3000 Hz or higher • Hexapod mount is readily fabricable by standard methods • Hexapod performance demonstrated via FE analysis Bruce C. Bigelow -- UM Physics

More Related