Progress on staves – mechanical & thermal

Core and materials

3

Corrugated core (QMUL)

• 60° inclusive angle (previously: 90°)– Angle has little effect

on stiffness– Easier to machine, can

use larger cutters– Easier to load pre-preg

into mould

• 13mm pitch – Large Flat Area for

adhesive

• Plan to make 2 planks with this core

4

Thermal performance of U-bend (QMUL)

• No foam results in 6°C reduction of run-away headroom• Not clear how well thermal contact in U-bend will be (bend and machining

tolerance)• Alternative: reduce bending radius with foam to end of straight sections

U-bend no corner foam

Inner module

U-bend full foam

5

Irradiation studies (Liverpool)

• Tested small samples of CF/HC sandwich– 3-ply (0/90/0) K13D2U/RS-3 (80gsm,

29%RC)– UCF-126-3/8-2.0

• 2 different glues used– Henkel Hysol 9396 – ACG VTA260: glue film with cure

temperatures ranging from 65°C to 120°C• Irradiated to 1.6×1015 p/cm2 (CERN PS)• Subjected to 3-pt bend and flat-wise tensile

test • Conclusions:

– Irradiated and non-irradiated samples behave similarly

– Failure modes for the two different glues different

• Hysol samples fail at HC – skin interface• VTA260 samples fail inside skin• Failure loads for VTA260 samples is 3-4

times higher than Hysol

Tooling

7

New stave manufacturing jig (Liverpool)

• CF/Nomex sandwich with steel plates for magnetic hold-down and embedded tooling fixations

• Vacuum channel• CF top plate• Inserts for location holes for skin

location parts and C-channel location jig

• Status– All CF components manufactured– Steel glued to base– Dry-fit of inserts on location plate –

done but bow of plate needs to be taken out before gluing.

– Full size grinder (1.8m) by modifying existing horizontal planer under construction – needed for grinding of top surface

– C-channel jig ready

8

Tape testing setup (Oxford)

• 2d stages 1600×500mm2, 5μm accuracy

• 2 independent probe heads to measure trace resistance and HV leakage

• Optional optical position referencing

• Idea is to use this for automated tape check-outs on reception and at various stages in the stave assembly

• Being assembled

9

Plasma-cleaning table (Liverpool)

• 1.4 × 0.3m2 area• Low power atmospheric plasma head: 20W, Helium

– Quite slow (10s of seconds per sq.cm.)• Motion control: 1mm (ish) accuracy• Need extensive programme of development to determine optimum settings for

different materials– CF face sheets– Cu/Kapton tapes (for gluing / co-curing)– Au bond pads (wire bonding)

10

Module mounting (RAL)

• Principals of operation– Retain the stave to a stable surface in frames– Drive a travelling microscope to where we expect the module corner fiducials to be– Use a a set of 12 mechanical manipulators to position modules one at a time so the

fiducials are in the right places, and then advance the module to the stave onto a glue pattern.

– The mechanical manipulators will then hold the module stationary for many hours whilst the glue cures

• Assumptions– We will have good optical references visible on the stave surface to place the module

with reference– The stave will be flat and smooth enough to allow a thin glue layer

• Status– We retain the old stavelet module mounting capacity – Stages, optics and stavelet frames at RAL– Software being developed – Granite table expected soon– Custom hardware still being designed and should start manufacture beginning of next

month

11

Module mounting (RAL)

Setup in the lab at RAL today – stages mounted on temporary table, surrounded by light curtain, with Z axis alignment laser temporarily in place. In the background the control and pattern recognition can be seen that will control the system

Light curtain Tx Prototype laser

Light curtain mirror

Locking and installation

13

Locking mechanics (Oxford)

• Injection moulded locking parts – 3 parts, locking by cam action

• Seems to do what we want it to do. – Firm grip when in locked position, and could slide when pushed

hard. – Sufficient gap to allow insertion

• Now test in insertion prototypes

14

First insertion tests (Oxford)

Guide rails: Rapid-prototyped profiles glued onto steel rods

15

3-stave sector prototype (Lancaster&Oxford)

• To investigate:– How the locking points and reference

points work– Positioning accuracy and repeatability;– Establish the edge deflection under load

• Possible later integration into RAL services mock-up

• Size is compatible with thermal cycling box – thermal tests possible

• Manufacture– Single-skin carbon-fibre cylindrical sector– Aluminium supporting structure (plates &

Bosch profile)– Cylinder end-flanges: manufactured from

aluminium (dowelled to support structure) in removable sections to allow hole-pattern iterations

– Interlinks for now simple design – to be updated when interlink design has progressed

– All mounting and reference brackets placed on cylinder using tooling designed for final assembly

16

Stave frame (QMUL)

• Stave supported on sprung loaded pins on locking mechanics (i.e. inner) edge

• Fixed blades on SMC (i.e. outer)

• Locking points are in a clearance slot and not used to hold the stave– To maintain envelopes during

module mounting and wire-bonding

• For stave installation mount rail on top of locking points for guidance during insertion

• Design is evolving as requirements are becoming clearer

Datum surface on both sides

Where more interdisciplinary effort is needed…

18

Stave ends• Coming together:

– EOS• Where? How large? Cooling? What connectors? Opto converters on

EOS? HV multiplexing on EOS? What access might we need to end of EOS?

– Stave mounting and installation• Need to constrain ends at two points (in particular for UK locking

mechanics. What are clearances needed for stave and installation tooling? Referencing stave coordinate system to global system

– Services:• How are services supported and protected (fibres)? How do we

avoid transmitting stress to the stave? Connection/disconnection technology, tooling and sequence? Clearances needed for service module?

– Barrel support structure• Interlink design?

– Access to staves after installation• Is removal of a faulty stave possible?

19

Assembly and installation tooling

• Interplay of stave assembly jig, stave frame, module mounting tooling, wire-bonding setup, electrical test systems, insertion and mounting mechanics– What defines coordinate reference systems?

How can we minimize reference system hierarchies?

– What clearances have to be maintained for each production process? Which envelopes are available at which step?

20

Supports, positional stability and alignment

• Need to provide system which allows track-based alignment to succeed– Stability (short time scale, 1d)

• Vibrations• Thermo-mechanical deformations

– Control of weak modes (medium timescale, 1m)• Define requirements (with track-based alignment

community)• Interplay of stave and global structure under the

constraint of minimal material?• Control of weak modes: Which combination of

engineering and alignment system can achieve this?

Finale

22

Roadmap for activities in the UK

• Build 4 mechanical full-size prototypes (probably 1 of these thermo-mechanical)– Using new jig to achieve improved flatness– Co-cured tapes (further statistics for process and dimensions)– Different cores (HC and corrugated)– Different cooling pipes (Ti and stainless steel)– Possibly different designs for U-bend thermal design

• Finish initial tests of locking mechanics• Build sector prototype• Work on end-region design – update sector prototype• Continue developing the stave frame – include into

sector prototype insertion studies• Include sector prototype into full-size barrel service

mock-up