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Calum I. Torrie on behalf of ALIGO US Suspension teams

ADVANCED LIGO SUSPENSIONS LSC-Virgo Meeting, Hannover 22 nd - 25 th October 2007 Suspensions/Isolation Working Group Parallel Sessions Welding Experiences : Output modecleaner and Recycling Mirror designs. Calum I. Torrie on behalf of ALIGO US Suspension teams

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Calum I. Torrie on behalf of ALIGO US Suspension teams

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  1. ADVANCED LIGO SUSPENSIONSLSC-Virgo Meeting, Hannover 22nd - 25th October 2007 Suspensions/Isolation Working Group Parallel SessionsWelding Experiences: Output modecleaner and Recycling Mirror designs Calum I. Torrie on behalf of ALIGO US Suspension teams http://lhocds.ligo-wa.caltech.edu:8000/advligo/UHVWelding & LIGO-T070190 G070656-00

  2. Welding in LIGO • Examples • LIGO I has history of welding stainless and Alum • e.g. LOS structure • HAM-SAS • aluminum (5083) welding practice & experience: LIGO-T060109 • ALIGO UK (RAL) • Why? • To meet LIGO Vacuum requirements • e.g. trapped contaminants could leak out! • Stiffness Not strength! G070656-00

  3. Why not use bolted structures? • Yes in principle could use bolted structures to achieve stiffness, but • History of problems! • Access • Ease of assembly • Bolts • Galling + Debris • Ref LIGO-T040111 by L. Jones & C. Torrie G070656-00

  4. LASTI: Quad Controls prototype LASTI: Quad Controls prototype – samples, discussions with welder + visual inspection G070656-00

  5. OMC Suspension eLIGO & AdLIGO • Why Alum? • Design history, had existing design from Quad structure • Mass Budget • Easy to mount non-suspended components during “metal” assembly • However wanted to better understand welds! G070656-00

  6. OMC – Original concept Butt Welds Gusset Weld Butt Welds Gusset Weld G070656-00

  7. Caltech 1st Alum weld sample for OMC suspension 1 Sided Butt Weld 2 Sided Butt Weld for Gusset G070656-00

  8. Inside Caltech 1st Alum weld sample G070656-00

  9. OMC Structure #1 Structure design and analysis: LIGO-T070205 G070656-00

  10. Welds & Welding • Tungsten Inert Gas (TIG) welding • manual welding process • Tungsten electrode, • inert gas and a separate filler material • high quality welds but it requires significant operator skill! Land ~ 0.039” [1mm ] LIGO-T070230 G070656-00

  11. Caltech 2nd Alum weld sample for OMC suspension 2 Sided Butt Weld G070656-00

  12. Inside Caltech 2nd sample at B3 • Sample cut polished, photographed and viewed under 10x magnification • Visual inspection • Good! • Further tests • refer to later slides G070656-00

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  14. X Rays • X Ray tests of butt welds carried out with local contractors • Base & leg • Gusset • Each weldment radiographed using two different exposures to ensure optimal inspectability G070656-00

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  16. Image of test results G070656-00

  17. Welding terms in the X-ray Inspection Report • Porosity • Formed by gas entrapment during solidification • LIGO seeks low porosity! • Crack • Fracture type discontinuity G070656-00

  18. Image of test results G070656-00

  19. Welding terms in the X-ray Inspection Report • Non-Fusion (NF) • a weld discontinuity in which fusion did not occur between weld metal and fusion faces or adjoining weld beads G070656-00

  20. OMC Test Results • On the OMC structure, only 3 welds were found to be acceptable per MIL-STD-2219 Class A • Most of the OMC weldments would not meet Class B because of very large porosity and / or excessive closely spaced porosity.   • 20 of the 56 OMC weldments would not meet the requirements for Class C because of their lack of fusion. G070656-00

  21. X Rays • Met to discuss X Rays • “How many of the 20 welds that show no fusion are buried inside and how many are through to the surface?” • Inconclusive! • Maybe this is good news! • So came up with a 3 point plan! Add image from Bob Still waiting for results on samples! G070656-00

  22. Plan - Chart Additional samples? Pass LSC Clean, Bake & RGA Scan Electro- polish welds I. Existing Structure Fail Dye Pen Dye Pen on ex. structure Pass Dye Pen test on samples Clean, Bake & RGA Electro- polish welds II. Weld Samples Fail *New* Drawings complete Parts machined With X Ray Or Dye Pen Inspection Clean Vac bake, Nitrogen bag Start TIG Weld III. *New* Structure TIMELINE: Mid – Oct Mid – Nov Mid – Dec G070656-00

  23. Proposed Dye Penetrant Test • Section of material with a surface-breaking crack that visible to the naked eye • Penetrant applied to the surface • Excess penetrant removed • Developer applied, rendering the crack visible • LIGO Compatible test wrt ability to make structure clean afterwards? • Dye Pen • Water soluble • Developer • Non-aqueous wet developer • Isopropyl Alcohol G070656-00

  24. New OMC Design LIGO-D060296 G070656-00

  25. New OMC Design G070656-00

  26. RM Suspension + Structure LIGO-T070169 and LIGO-T070238 G070656-00

  27. RM Tests & History • 304 SSTL Weld Sample • LIGO I LOS Structure G070656-00

  28. Conclusions / Outcome • Idea is that all of this work will lead to ability to better classify welds for Advanced LIGO e.g. class C low porosity no cracks! • To achieve this probably also consider additional weld samples e.g. • To match new OMC design • RAL design see picture & previous talk • RM design G070656-00

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