I-Beam R&D

E Anderssen, M Garcia-Sciveres, N Hartman, J Silber

Past Work

• Developed tooling and techniques for 1m I-Beam• The technique was to use non-closed section

laminates (low sectional inertia) and bond them into stiff assemblies

• Method allowed for very accurate parts• Geometry was for a cartoon layout, but feature sizes

were approximately correct moving to new shape• Looking to investigate ways to reduce adhesive mass• Improve local stiffness, e.g. different laminates

Symmetric Tool

• Previous tool had canted Web (radial when installed)

• Original method shown above, separate parts laid up, then tooling used to bond together

• Thermal Tiles bonded on after, tooling registers to Granite table for accuracy

Matched Metal Die and Trapped Rubber Tooling

• Tool halves need registration during ‘clave cycle (bag whole tool)• Previously RT Bond with Tooling on Granite Surfaces• Silicone pressure pad cast in place for compaction in joint• Size Silicone pad so expansion times bulk modulus does not exceed force from

registration plates in vac bag with clave pressure• Lighten tools with pockets to reduce thermal mass

Cast Silicone Pressure Pad

Surfaces RegisterTool Halves in Autoclave

Bladder or Trapped Rubber Tool

• Does not have ‘Web’ piece, just parts A/B, then section is closed top and bottom • Registration plates could be tool surfaces for top/bottom pieces—make

separate tooling part that can be sized appropriately to close tool on composite parts (re-use registration plates)

• Either Trapped rubber, or bladder (prefer bladder) for compaction• Whole tool is bagged.

Machined Al tool surface

Goal is co-cured ‘Core’

• Core is what top/bot thermal plates are attached• Could size cross-section to newest layout for outer

layers and tilt• Clearly easiest to try with straight sections and some

symmetry, no web-tilt and/or bent ends• Suggest only incorporating features which affect

fabrication and/or thermal performance• This may fail, as end-product has high sectional inertia

—must come out of tool straight to achieve accuracy• We do have some confidence this is possible, but

tooling is compatible with old process

Thermal Tile Studies

• Tube presently bonded in with BN/Epoxy• Foam machining requires first co-curing foam

blanks to laminate• Have made stavelets using CE Film adhesive,

elevated temp cure, after foam machining• Which method to use depends on how tool

and assembly interact

Thermal Tile Machining

Thermal Tile Co-Cure

• After Machining, have co-cured tube and another layer of CFRP

• Potential method to ‘seal’ foam for later use of RT cure Adhesive to bond onto ‘Core’ structure

‘Bent’ I-Beam Study

• Layouts shown next few slides• Further study is required, but part of R&D effort

will be to understand how to fabricate• Options considered– One-piece lamination (difficult tooling), feasible for

inner, but not outer– Bond-on ‘Bent’ piece later

• Cooling Tubes and Thermal tiles are more difficult to fabricate, but have proof of concept already

Straight inner beam

Bent outer beam AffixedTo endplate

Affixed to beampipe

Layouts Considered

‘Bent’ active area allows for shorter layout, leading to less material at high eta (see lower layout, inner beam)Several Shapes were considered, above is nominal Z-layout

I-Beam Web Build Angle

0 angle 20 angle 40 angle

It would be great to build symmetric I-beams, but they don’t fit so well….

40mm tall I-beam

Zero Angle I-beam at 10 degrees

30mm tall I-beam

10 Angle I-beam at 10 degrees

30mm tall I-beam

20 Angle I-beam at 10 degrees

30mm tall I-beam

30 Angle I-beam at 10 degrees

30mm tall I-beam

40 Angle I-beam at 10 degrees

30mm tall I-beam

I-beam Build Angle Optimization

0 5 10 15 20 25 30 35 40 45

-30

-20

-10

0

10

20

30

40

50

60

Ibeam LengthClearance to next Ibeam

Best combination of short length and clearance is near20 degrees (happens to be our initial choice….)

Interference on Bent I-beams above 30mm height

40mm tall I-beamAt 0 degree build angle

Straight webs don’t work….

Interference on Bent I-beams above 30mm height

40mm tall I-beamAt 20 degree build angle

Still Interference….

Layout Summary

• Inner I-beams pose no problems– 2cm inner modules solve interference problem– And I-beam is naturally staight

• Outer I-beams (same modules inner and outer) are problematic

Plan• Develop working ‘Core’ fabrication for straight

section• Study methods to attach ‘Bent’ core extensions• Develop fabrication procedure for Thermal tile

with co-cured foam and integrated tubes• Investigate assembly procedures that would

allow an integrated single tube on inner and outer thermal tile

• Assembly will dictate what can and cannot be co-cured together

Backup

General Note:All uses of ‘Final’, ‘Ultimate’, their synonyms, et cetera, should be banned from all descriptive nomenclature within our or any community in which we work to describe a design which has not been built.

Things change after you plan for them not to, these synonyms just look foolish during late stage reviews, e.g. Ultimate v2.1 is hardly “Ultimate.”

That said, use with ‘air quotes’ is allowed, but should be frowned upon…

“Final” Ibeam layout• 30 outer staves

– 2x1 alternate with 2x2– 12.5 to 15 tilt angle possible (at center) – drawings are for 12.5

• 14 inner staves– 2x1 everywhere– 12.5 center tilt angle

• Module Sizes– Active

• 16.8• 33.9

– Overall• 18.8• 37.9

Layout Plot

30 outer14 inner

Tilt Effect increases with tilt angle and with reduction in radius

This is outdated stave shape, anglesare for reference

Overlaps are mostly ok, but centering of the module here will be problematic

2x1 Layout with notch in bend – note that with proper dimensions, it entirely cuts web for about 22mm long

There is also minimal clearance at the end corners

If we go down to a radius of 3mm and tilt angle of 15, we get up to 1.25mm clearance. This is only anIssue at the very end of the stave.

Summary

• Tilt angle is a real limitation to the symmetric I-beam

• Clearances (corner and cutout) are significantly problematic

• Symmetry is nice, but these clearance issues give pause

• Should we prototype the symmetric beam, knowing we might need to go back to a sheared one like before?