BNL Yale Mechanical Stave Developments BNL David Lynn

BNL & Yale Mechanical Stave Developments BNL: David Lynn, Marc-Andre Pleier, Anatoli Gordeev, Russ Burns, Ken Sexton Yale: Paul Tipton, Will Emmet, Tom Hurteau ATLAS Upgrade Week, CERN, Nov 11 th, 2010

Outline • Final 35 cm stavelet thermal imaging results • CFdesign thermal simulation software issues and flow measurements • 1. 3 m stave construction and initial thermal measurement • Stave Frames and Brackets

1. 3 Meter Stave Core Construction Changes from 2009’s 1 meter stave Dimensions 130 cm x 12 cm vs 100 cm x 10. 7 cm Facing Material 220 -280 um thick K 13 D 2 U vs 430 um thick K 13 C 2 U Facing Texture textured both sides vs smooth outside, texture inside CF Tubes Custom, thick walled vs commercial, thinner wall CF Tubes Better diamteer tolerance vs poor diameter tolerance Pipe Bend Dual diameter, closer to end vs single diameter further from end Fabrication • New CF tube had thicker walls dissuaded us from using previous technique of using a steel bar inside tube and magnets to hold CF tube in assembly fixture. Required more steps to attach CF tubes and foam and honeycomb to first facing • Did not use vacuum bagging (wasn’t clear such force is necessary) and afraid things might move during bagging and vacuuming procedure • Much more practice in gluing technique…aim to improve • Thinner facings much more delicate…. more careful handling

New Pipe Bend and Location 35 cm stavelet 1. 3 m stave Gordeev, BNL 7 -12 -10 4

Simulation Comparing Effect of Change in U-turn Location and Shape 35 cm stavelet • Simulation suggests large improvement 1. 3 m stave

Foam Issues Allcomp Carbon Foam, 0. 5 g/cc • Used open-cell Allcomp foam to replace closed-cell Poco • Machines better, but still leaves gap with 4 mm thick foam and 1/8” (3. 175 mm) pipe • We use compliant CGL…worry that CGL may seep into open cell foam and be drawn away from pipe • Decided to seal foam with hysol BN loaded epoxy Allcomp with hysol seal Poco top/Koppers k-foam bottom Note jagged edge

Possible solution to Allcomp “ragged edge” problem • Create a 1 -2 mm thick layer of Hysol on interface surface of foam and allow to cure; • Machine with ball endmill as before; • Apply coating of Hysol as before to seal pores on semi-cylindrical surface… Note improved edge Apply Hysol layer Machine foam as before

Allcomp Foam Thermal Conductivity Measurements Foam Allcomps own laser diffusivity measurements yielded 73 W/m-K and 85 W/m-K on two samples AL Calibration Block Al Measurement gives K = 79 W/m-K SS Measurement gives K = 93 W/m-K SS Calib Block Foam SS Calib Block

Gluing of CF tubes to First facing • Used shim springs to hold cf tubes in place due to thicker walled tubes (previously could use magents and steel rods inside cf tubes • Thus cf tubes glue-up becomes two step process

Glue Joints Apply hysol only to inside: many tests done to get epoxy to bleed to outside without overflow Outside Inside Only imperfection in outer glue joint, but glue is in gap Space left for shim spring

Foam-Pipe Assembly Attachment to First Facing

Honeycomb attachment • Honeycomb dipped in ~8 mil of epoxy • Rubber sheet placed between honeycomb and aluminum blocks and brass rails

2 nd Facing attachment • 1 st dip Mask off CF tubes and dip assembly in 10 mils hysol (honeycomb + foam) • 2 nd dip. Unmaxk CF tubes and dip tubes on elevated rails containing 2 mils epoxy

2 nd Facing attachment

• Looks very good Finished Stave • 2 nd glue joint looks very good • Appears straight • Facing remains flat • Detailed characterization to follow Side 1 Side 2

Mass and Radiation Length of Stave I area[cm^2] Pipe Foam CGL Facings CF Tubes Closeouts Hysol Honeycomb Total G. Gilchriese Estimate July 08 1560 Note pipe is about twice what next will be (10 mil walls versus present 20 mil walls) x 12/10 Weight [g] X 0 [g/cm^2] RL [%] RL norm to det [%] 106. 3 13. 9 0. 49 0. 59 45. 6 43 0. 07 0. 08 15 33. 4 0. 03 104. 8 43 0. 16 0. 19 38. 7 43 0. 06 0. 07 4. 2 43 0. 01 30. 7 42. 4 0. 05 0. 06 24. 7 43 0. 04 0. 00 370 0. 89 1. 07 Expect RL =. 64% with new ss tubes Expect mass of pipe to reduce by factor of 2 next stave (10 mil walls rather than 20 mil) Expect mass of CF tubes to reduce by factor of 3 next stave Custom tubes had 1. 03 -1. 09 mm walls after sanding New custom tubes have. 30 -. 38 mm walls after sanding

Comparison of US Stave and UK Normalized Stavelet Mass • UK built a 0. 5 m stavelet for same stave-09 program • Result is that both builds are comparable in mass(and consistent with original LBNL estimate) • This is a good result in that using slightly different designs and different assembly techniques yields similar (and good!) results. • Some small improvements in the future may be expected • UK chart from “The Design, Contstruction and Testing of a UK Stavelet”, Peter Cooke, Tim Jones, and Peter Sutcliffe Pipe Foam CGL Facings CF Tubes Closeouts Hysol Honeycomb glue Total Stave UK Stave x 1. 3/0. 5 Weight [g] 106. 3 98. 40 45. 6 56. 80 15 104. 8 103. 80 38. 7 10. 80 4. 2 16. 40 30. 7 24. 7 18. 40 45. 7 33. 80 370. 00 338. 40

Test Plan • Thermally characterize performance of chilled stave using ambient still-air and net radiation to uniformly provide power to stave (first preliminary result in next few slides) • Use these results to understand reliability of CF design ambient calculations…smooth and simple surface of stave core is an easy object to study • Precision measure profile of stave at room temperature and chilled to ~ -30 C • Perform bend tests and extract facing modulus to compare with direct facing modulus measurements • Use to study aluminum support brackets (see later slide) • Not clear if should make into full mechanical model. Have parts, but is time consuming. UK has already constructed full-scale thermo-mechanical model

IR Camera Calibration and Determination of Emissivity • Emmisivity =. 89 and ambient box temperature = measured was result of calibration of our standard black spray paint and gave good correspondence • Intended to do new calibration and surface of stave can’t be painted and we expected a different emissivity value would be needed. • However e =. 89 gave excellent correspondence over full range of temepratures -25 deg-C to 38 deg-C.

Temperature Profile of 1. 3 m x 12 cm Stave Temperature [Deg-C] 12 c m 1. 3 m Input power from ambient convection/radiation is approximately 150 W (determine by temperature difference of coolant at inlet and outlet and by flow rate)

Temperature Profile of 1. 3 m x 12 cm Stave Temperature profile very uniform in longitudinal direction

Temperature Profile of 1. 3 m x 12 cm Stave Temperature profile very uniform in longitudinal direction

Temperature Profile of 1. 3 m x 12 cm Stave 201 Slices 3. 2 mm apart U-Turn Half of Stave • Temperature profile uniform in longitudinal direction • Very little additional temperature gradient at U-turn end • Can this technique be as part of QA of stave cores? 13 temperature profiles, 3. 2 mm apart at UTurn end of Stave 201 Slices 3. 2 mm apart Pipe Inlet/Outlet Half of Stave

Barrel Support Bracket Prototyping • Demonstrated concept with stereo-lithographic plastic brackets on 1 meter stave in 2009 • Plastic brackets deform after one day and stave falls out • Currently fabricating brackets in aluminum to study end insertion • Final design needed to be fabricated in carbon fiber 2009 Bracket Demonstration Current Al Bracket Prototype

US Style Transport and Storage Frame Prototype aluminum elastic brackets

US Style Transport and Storage Frame and Al Barrel Support Bracket • Frame made from inexpensive 80/20 Aluminum T-slotted Framing Bars (<$50/frame small quantity) • Brackets “hand” machined…need to look at alternative • Friction currently to high with these frame brackets…. work continuing • Study of first Aluminum support bracket just beginning.

Plans • Characterize thermal and mechanical performance of 1. 3 meter stave • Prepare to build Co-cured 1. 3 meter stave with co-cured facings from LBNL • Continue stave frame/support work • Thermal measurements of Allcomp foam (three axis) and epoxies. Mechanical measurements of Allcomp foam