Strip Stave Status & Plans at Yale Yale: Paul Tipton, Will Emmet, Tom Hurteau

Strip Stave Status at Yale One complete and one dummy (no foam/cooling tubes) completed; Materials and tooling on hand to construct at least one more stavelet; We have four CF facings, but would like to use one to make more tensile samples for the Instron mechanical testing machine here on campus; Two stavelet survey/storage frames completed, one currently in use at RAL; We will need another frame for the full-sized stave near term.

Future Plans at Yale Near-term: Complete Stavelet09-3 (by November?) Prepare additional CF facing coupons per ASTM-D3039 for Instron (determination of Young’s Modulus) Work in concert with BNL on carbon foam thermal and mechanical property testing Longer term: Trade study of more lower-density foam (less honeycomb) vs. stave stiffness, thermal performance and radiation length budget Tube-foam interface development (Hysol as an edge-reinforcement, etc.)

1 st 1.3 Meter Stave Fabrication D. Lynn For BNL/Yale

Changes from 2009’s 1 meter stave Dimensions 130 cm x 12 cm vs 100 cm x 10.7 cm Facing Material um thick K13D2U vs 430 um thick K13C2U 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

Tolerance on Commercial Source Poor Commerical Source used on 2009’s 1 meter stave

Custom CF tube diameters (Hardy Composites) Before/After Sanding on Lathe

1.3 meter stave vs 1 meter stave 1.3 meter stave vs 35 cm thermal- mechanical stave New Pipe bends and Locations Still might to move pipe further towards end

area[cm^2]1560Note 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 Foam CGL Facings CF Tubes Closeouts Hysol Honeycomb Total Gil’s Estimate July 08 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 stave Custom tubes had mm walls after sanding New custom tubes have mm walls after sanding ( mm one end before sanding, mm other) Expect RL =.64% with new ss tubes

StaveUK Stave x 1.3/0.5 Weight [g] Pipe Foam CGL15 Facings CF Tubes Closeouts Hysol30.7 Honeycomb glue Total Comparison of 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 Result is that both builds are comparable (and consistent with earlier LBNL estimate)

Facing Width Concerns Relating to Gluing, Grinding, Support (leaves little room for glue on outer side)

Facing Thickness

K13D2U Tensile Modulus Measurement Stress [Pa] BNL used 280 um for facing thickness, LBNL 220 um. If BNL uses 220 um, get 250 Gpa instead of 200 (LBNL got 300 Gpa on previous facing)

For comparison we measured 160 Gpa of K13C2U facing, thickness 430 um Glasgow on same facing with Instron got 126 Gpa with 460 um facing. If they had used 430 um thickness, would have got 135 Gpa. Difference is > 15 % K13D2u. From Will’s stavelet bend tests, got 320 Gpa reasons for discrepancies, edge effects/cuts on our thin strip, different facing sample, non-uniformity it facing sample? Tensile Measurement Discussion

Prototype 2 Fabrication Sequence (for flatness and CF tube location) 1.Assemble parts as shown. V-blocks precision locate CF tubing. Honeycomb height > 3mm. Glue bottom facing to honeycomb and foam. Vacuum bag to flatten honeycomb to bottom facing. Honeycomb is dipped in epoxy. 2.Grind honeycomb flat to 3 mm with better than 25 um tolerance. 3.Turn over assembly. 4.Mount again on original fixture and glue second facing. Lexan plate provides uniform pressure on first facing. 0. Glue foam-tube assembly to first facing (not illustrated). Foam is pre-machined to 3mm height.

Prototype III Fabrication Sequence (for flatness and CF tube location) 1.Assemble parts as shown. V-blocks precision locate CF tubing. Honeycomb height > 4mm. Glue bottom facing to honeycomb and foam. Vacuum bag to flatten honeycomb to bottom facing. Honeycomb is dipped in epoxy. 2.Grind honeycomb flat to 4 mm with better than 50 um tolerance. 3.Turn over assembly. 4.Mount again on original fixture and glue second facing. Lexan plate provides uniform pressure on first facing. 0. Glue foam-tube assembly to first facing (not illustrated). Foam is pre-machined to 3mm height. Step 4 is different than that done for prototype II stave

Gluing of CF tubes to First facing

Glue Joints Outside Inside Apply hysol only to inside: many tests done to get epoxy to bleed to outside without overflow

Foam-Pipe Interface Attachment

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

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

Test Plan Mechanical 1)3 pt bend test, multiple weights, extract modulus and compare 2)Unloaded deformation warm vs cold (room temp vs -30C), 3pt and 4 pt 3)Don’t have brackets for bracket support measurements Thermal Stave only, chilled, ambient heat load (emissivity issues?)

US Style Frame

Near Term Plans, BNL and Yale BNL 1.3 m Stave Tests Deformation measurements, room temp and -30 deg-C Bend Tests Thermal imaging tests Finish US-style Stave Frame Foam thermal conductivity in y and z direction Write paper on short stave thermo-mechanical model and 1 meter stave fab/mechanical tests Yale Top-Hats for stavelet I (and maybe stavelet II) Foam measurements (modulus, shear, etc) Stavelet III (for Yale tests, possibly used as DC-DC stave) New thicker frame (still needs input from Carl) Finish flow vs simulation for other IDs

Other Plans Yale Test coupons for ultrasonic imaging Thermal deformation measurements of LBNL co-cured stavelet? BNL Second 1.3 m Stave fabrication (with Yale) Thermo-mechanical model using one of the 1.3 m staves Thermal conductivity of epoxies Aluminum brackets for stave support (proto of carbon fiber bracket) CNC at Yale Both Stave design variations titanium pipes? Questions remain about thermal simulation software