BNL & Yale Mechanical Stave Developments

BNL: David Lynn, Marc-Andre Pleier, Anatoli Gordeev, Russ Burns, Ken SextonYale: Paul Tipton, Will Emmet, Tom Hurteau

ATLAS Upgrade Week, CERN, Nov 11th, 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

Changes from 2009’s 1 meter stave

Dimensions 130 cm x 12 cm vs 100 cm x 10.7 cmFacing Material 220-280 um thick K13D2U vs 430 um thick K13C2U Facing Texture textured both sides vs smooth outside, texture insideCF Tubes Custom, thick walled vs commercial, thinner wallCF Tubes Better diamteer tolerance vs poor diameter tolerancePipe 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

1.3 Meter Stave Core Construction

Gordeev, BNL 7-12-10 4

New Pipe Bend and Location

35 cm stavelet 1.3 m stave

35 cm stavelet

1.3 m stave

Simulation Comparing Effect of Change in U-turn Location and Shape

• Simulation suggests large improvement

Poco top/Koppers k-foam bottom

Allcomp Carbon Foam, 0.5 g/cc

Allcomp with hysol seal

Note jagged edge

Foam Issues

• Used open-cell Allcomp foam to replace closed-cell Poco• Machines better, but still leaves gap with 4mm 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

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…

Apply Hysol layer Machine foam as before

Note improved edge

Allcomp Foam Thermal Conductivity Measurements

Foam AL Calibration Block

Foam SS Calib BlockSS Calib

Block

Al Measurement gives K = 79 W/m-KSS Measurement gives K = 93 W/m-K

Allcomps own laser diffusivity measurements yielded 73 W/m-K and 85 W/m-K on two samples

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

Outside InsideApply hysol only to inside: many tests done to get epoxy to bleed to outside without overflow

Space left for shim springOnly imperfection in outer glue joint, but glue is in gap

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

2nd Facing attachment

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

2nd Facing attachment

Finished Stave

Side 1

Side 2

• Looks very good

• 2nd glue joint looks very good

• Appears straight

• Facing remains flat

• Detailed characterization to follow

area[cm^2] 1560 Note pipe is about twice what next will be(10 mil walls versus present 20 mil walls)

x 12/10 Weight [g] X0 [g/cm^2] RL [%] RL norm to det [%]Pipe 106.3 13.9 0.49 0.59Foam 45.6 43 0.07 0.08CGL 15 33.4 0.03 0.03Facings 104.8 43 0.16 0.19CF Tubes 38.7 43 0.06 0.07Closeouts 4.2 43 0.01 0.01Hysol 30.7 42.4 0.05 0.06Honeycomb 24.7 43 0.04 0.04 0.00Total 370 0.89 1.07

G. Gilchriese Estimate July 08Item Low Nominal HighFacings 0.06 0.16 0.26Honeycomb 0.03 0.04 0.05Foam 0.04 0.09 0.11Epoxy 0.01 0.03 0.04Thermal glue 0.02 0.04 0.05

Subtotal 0.16 0.36 0.51SS Tube 0.19 0.3 0.42

Subtotal 0.35 0.66 0.93Tube rails 0.03 0.06 0.09

Subtotal 0.38 0.72 1.02End closeouts 0.01 0.015 0.02

Subtotal 0.39 0.735 1.04

Mass and Radiation Length of Stave I

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 staveCustom tubes had 1.03-1.09 mm walls after sanding

New custom tubes have .30-.38 mm walls after sanding

Expect RL = .64% with new ss tubes

Stave UK Stave x 1.3/0.5 Weight [g] Pipe 106.3 98.40Foam 45.6 56.80CGL 15 Facings 104.8 103.80CF Tubes 38.7 10.80Closeouts 4.2 16.40Hysol 30.7 Honeycomb 24.7 18.40glue 45.7 33.80Total 370.00 338.40

Comparison of US Stave and UK Normalized Stavelet Mass

• UK chart from “The Design, Contstruction and Testing of a UK Stavelet”, Peter Cooke, Tim Jones, and Peter Sutcliffe

• 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

• 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 ~ -30C

• 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

Test Plan

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

1.3 m12 c m

Tem

pera

ture

[Deg

-C]

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

13 temperature profiles, 3.2 mm apart at U-Turn end of Stave

201 Slices 3.2 mm apart U-Turn Half of Stave

201 Slices 3.2 mm apart Pipe Inlet/Outlet 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?

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