atlas lbnl pixel support study 1 w.o. miller hytec atlas pixel detector support structure status and...

LBNL Pixel Support Study 1W.O. Miller HYTEC

ATLAS

ATLAS Pixel DetectorSupport Structure Status

andFuture Developments

February 19, 1999

W. Miller

HYTEC


ATLASMeeting Topics

• Review frame design status– Recent FEA results and plans

• Discuss trade-off of sandwich core materials, carbon foam versus honeycomb– in terms of performance

• definite cost impact

• Discuss prototypes for testing and test objectives– Frame components

– Frame sub-assembly


ATLAS

FEA of ATLAS Pixel Support FrameDescription Objectives Approach Element

typesIssues

1. Overall frame analysis-w/ocutouts

a. Sagb. Natural freq.

a. Must include conesb. Must include jointsc. Must include cored. Must include barrel effects

a. Shell4Lb. Beams

a. Judge effect of 8 point connectionb. Model SCT interactionc. Not adequate model of jointinteractions

2. Overall frame analysis-w/cutouts

a. Sagb. Natural freq.

a. Must include conesb. Must include joint contactsc. Must include cored. Must include barrel effects

a. Shell4Lb. Beams

a. Judge effect of cut-outsb. Not a full model of jointinteractions

3. Panel analysis-two adjacentpanels as a minimum

a. Load transferb. Stresses

a. Must include tube, panelcorner, and panel sandwich

a. Solidb. Shell4c. Beam

a. Interaction within jointb. Panel without and with cut-outs

4. Joint analysis-in form of strip a. Load transferb. Stresses

a. Must include core andattachment of joint to facings

a. Solidb. Shell4

a. Single corner block reactions

5. Prototype panel a. Predict staticbehaviorb. Predict natural freq.of single unsupportedpanel

a. Include joints, and coreb. Free suspensionc. Correlate results withexperiment

a. Solidb. Shell4c. Beam

a. Predict load transfer of joint withappropriate model of boundaryconditionsb. Predict effect of cut-outs

FEA Studies

Work Completed Nearing completion


ATLASFrame Concept

Flat Panel Frame Assembly•Disk Regions-2•Central Region-1•End cones-2

Frame corner connections

Frame cutouts


ATLAS

Current Studies Based on 250mm Outer Radius

Frame Size


ATLAS

Solution to Dynamic and Static Stiffness

• Problems confronting developing a reasonable solution– Minimum mass and radiation length requirement must be preserved

– Envelope more or less fixed• limits options for solving dynamic stiffness issue

– To avoid over constraining detector that causes undesirable strains the lateral restraint of detector must be limited to two points• occurs at the extreme ends of the frame• lateral reactions to acceleration type loads produce purely radial

reaction, direction of lowest stiffness due to load concentration

• Frame studies focusing on:– Frame construction details to achieve 70 to 100 Hz natural frequency

in lateral direction

– Gravitational sag less than 10µm

Frame Issues


ATLASFEA Results

Example Frame Without Cutouts, No Corner Effects(Both XN50 and Higher Modulus Fiber Option)

Notice that substantial stiffness comes from using end rings•increased core stiffness produces ~7% effect, with XN50


ATLAS

Static Solution with High Modulus Fiber(Typical of XN80, P120, or K13C2U)

• Model parameters– Facings high modulus fibers,

e.g., XN80, P120, and K13C2U– Core 68.1kg/mm2 (97000psi,

Hexcel 3/16” core size)– 2 radial end plates, separated by

25 mm, bounded by sandwich facings. Double facing thickness between 25mm spacing (0.6mm)

– Total mass of structure and pixel detector 38.38kg

• Loading 1G vertical– Peak deflection 6.07m, more or

less uniform along length

Flat Panel Frame


ATLAS

• Model parameters– Transverse connection at

individual frame sections limited to 8 corner points

– Core 68.1kg/mm2 (97000psi, Hexcel 3/16” core size)

– 2 radial end plates, separated by 25 mm, bounded by sandwich facings. Double facing thickness between 25mm spacing (0.6mm)

– Total mass of structure and pixel detector 38.39kg

• Loading 1G vertical– Peak deflection 7.28m at mid-

section

Static Solution with High Modulus FiberIncluding Corner Effects

(Typical of XN80, P120, or K13C2U)

Flat Panel Frame

Frame sections

Load transfer at corners only


ATLAS

Solutions with High Modulus Fiber(Typical of XN80, P120, or K13C2U)





– Centerframe light weighted

• Solution static and dynamic– Peak deflection 10.2m at mid-

section– 1st mode 46.66Hz

Static: 10.2m

Dynamic: 46.66 Hz

Flat Panel Frame


ATLAS

FEA Comparison Between Structures(For Light Weighting In Center Panel Only)

Frame materialskg/mm2

Cone materialskg/mm2

Result Special modifications

Sol. type Loading Mass Model Facing Core Facing CoreStatic 1G Vertical 38.39 Flat panel 1.69 104 68.1 1.69 104 68.1 7.28m P120 w/End rings,

and frame sectionconnections at 8points only

Dynamic none 38.39 Flat panel 1.69 104 68.1 1.69 104 68.1 49.53Hz P120 w/End rings,and frame sectionconnections at 8points only

Static 1G Vertical 37.46 Flat panel 1.69 104 68.1 1.69 104 68.1 10.2m P120 w/End rings,and frame sectionconnections at 8points only,centerframelightweighted

Static 1G Vertical 37.46 Flat panel 1.69 104 68.1 1.69 104 68.1 46.66Hz P120 w/End rings,and frame sectionconnections at 8points only,centerframelightweighted

Flat Panel Frame

Frame modifications needed to meet design goals


ATLAS





– Entire frame light weighted, total mass 36.9 kg, including detector elements

• Solution static– Peak sag of outer barrel, ~13µm– Peak sag overall, ~16.3µm

Solutions with High Modulus FiberWith All Cutouts Included


Flat Panel Frame


ATLAS






• Dynamic solution– fundamental mode, 38.03 Hz

Flat Panel Frame

Solutions with High Modulus Fiber(Typical of XN80, P120, or K13C2U)


ATLAS

Solutions with High Modulus Fiber Light-weighted Frame (Typical of XN80, P120, or K13C2U)

Flat Panel Frame





and frame sectionconnections at 8points only, lightweighted frame,0.6mm facings endsection

Dynamic none 36.9 Flat panel 1.69 104 68.1 1.69 104 68.1 38.03Hz P120 w/End rings,and frame sectionconnections at 8points only, lightweighted frame,0.6mm facings endsection

Dynamic none 36.9 Flat panel 1.054 104 68.1 1.054 104 68.1 30.99Hz XN50 w/End rings,and frame sectionconnections at 8points only, lightweighted frame,0.3mm facings endsection


ATLAS

Proposed End Reinforcement(Added after Disk Installation)

• Tubular end truss– Demountable– Does not block passage of

services to any great extent– Tubes are 10mm OD with a

0.6mm wall, composite construction similar to longitudinal members

Flat Panel Frame

Tubular members tieinto longitudinal tubes


ATLAS

End Tubular Frame Connection

• Geometry of end piece– Concept depicted is an

illustration– Details of end piece need to be

worked out– Construction feature will

incorporate some light-weighting

– Pin connection will have zero clearance feature to remove play

Flat Panel Frame


ATLAS




– 2 radial end plates, separated by 25 mm, bounded by sandwich facings. Double facing thickness in disk region

– 4-10 mm dia. corner end beams reinforcements, 0.6mm wall


• Static solution– Gravity sag, ~10.43m

Solutions with High Modulus FiberWith End Reinforcement


Flat Panel Frame


ATLAS







• Dynamic solution– fundamental mode, 77.5 Hz

Flat Panel FrameSolutions with High Modulus Fiber

With End Reinforcement(Typical of XN80, P120, or K13C2U)


ATLAS

Solutions with XN50 LaminatesWith End Reinforcement

(illustrate effect of lower modulus laminate)







Flat Panel Frame

Gravity sag increased to 16.4m


ATLAS





and frame sectionconnections at 8points only, endtubular truss

Dynamic none 37.53 Flat panel 1.69 104 68.1 1.69 104 68.1 77.5Hz P120 w/End rings,and frame sectionconnections at 8points only, endtubular truss

Dynamic none 37.53 Flat panel 1.054 104 68.1 1.054 104 68.1 66.46 XN50 throughout,except high modulustubes, end tubulartruss

Static 1G Vertical 37.53 Flat Panel 1.054 104 68.1 1.054 104 68.1 16.4m XN50 throughout,except high modulustubes, end tubulartruss

Dynamic none 38.50 Flat Panel 1.054 104 68.1 1.054 104 68.1 67.58 XN50 throughout,except high modulustubes, end tubulartruss, all laminates0.6mm

Flat Panel Frame

FEA Summary for Light Weighted Structure(End Flat Panel Structure 0.6mm facings)


ATLAS

Summary Remarks on FEA

• Reinforcements to the very ends of the frame produced positive results in raising the first vibration mode--with kinematic mounts – 77.5 Hz for frame with ultra-high modulus composites

– Drops to 66.46 Hz for XN50, and 0.6mm laminate facings at end sections• gravity sag increases from 10 to 16.4 m

– Eliminating the end reinforcements-with XN50 composite• Gravity sag increases from 16.4 to 17.7 m, small effect • Resonance drops to 36.7 Hz if we eliminate the reinforcements• Resonance would decrease further if we use 0.3mm facings on the end

sections---30.99Hz

• Clear benefit to reinforcements at frame ends• Increased facing thickness on ends is beneficial, as is the use of

higher modulus laminates.

Flat Panel Frame


ATLAS

A Concept for the SCT/Pixel Mounting Interface

• Desirable attributes for mount– kinematic to extent practical– Four point support

• 1 point XYZ• 1 point XY• 2 points Y

– All support points are adjustable vertically

– Pixel frame reinforced locally to resist lateral loads

• Issues– Need to be assured that SCT

channel design is fixed in geometry and stable

– Look into pixel frame reinforcements and mount materials

Pixel Support

40mmX10mmX3mmSCT mounting channel

(must be replaced with end plates)


ATLAS

Restraint at Corners Vary

• Mount concept– Vertical adjustment for leveling

detector– Conical seat and V-groove track

at opposite end position detector laterally• Restrains X and Z, and rotation

about vertical axis

– Simple flat contact permits movement in X and Z

• Considerations– SCT support dimensional

accuracy• to what extent can we rely on

location of channel?• Must we shim?

Pixel Support

Vertical adjustment

lock

Section views

cone

flat


ATLAS

A Concept For Disk Ring support

• Mount considerations– To avoid excessively tight frame

assembly tolerances, we machine and locate precision inserts

– Bushings are bored after bonding• this fixes the azimuthal and Z

location for V-groove receivers, within 10µm, possibly better

– Three V-groove blocks are positioned and bonded to bushings• fixture used in bonding the V-

groove receivers. positional tolerance can be improved by using bond clearances to an advantage if necessary

• three precisely located balls on the fixture locate the V-grooves radially, and rotationally

Disk Support

Disk support ring mounts


ATLAS

• Assembly sequence– Disk assembly inserted into

frame– Spherical balls on mounting ring

are placed onto three V-grooves– Spring keeper inserted from

outside to restrain spherical ball in V-groove

– Spring keeper is guided by the machined bushing bonded in the frame structure and fixed in place on the outside of the frame

• Considerations– Required spring force to resist

movement of disk from extraneous forces caused by services

– Material selection

Disk Support

Disk Support Ring Retention

spring keeper

V-groove

spherical ball

sandwich ring


ATLAS

• Adjustment features– R- disk position is obtained by

precise location of three point ball support in three V-grooves

– Final positioning of disk provided by adjustment screw (fine thread)

– Adjustment screw provides pure axial motion, as well as tip/tilt

• Considerations– Material selection of individual

components• use composite materials to extent

practical• to what extent metallic (Be)

elements are desired is unclear at this time

– Demonstrate zero backlash at component level

Disk Support

Disk Ring Position Adjustment

adjustment screw


ATLAS

Objective: Test Frame and Support Interactions

• Prototype test considerations– Frame performance is strongly

influenced by the stiffness in the end sections

– Local stiffness of the frame dependent on frame internal reinforcements

– Testing with the end section will investigate adequacy of this reinforcement, as well as the general performance of the lightweight structure

– Test of interface connection of the central frame will also be covered

Frame Prototype

For test removeSCT mount


ATLAS

Process of Establishing Fabrication Cost Estimate

• History– 1st cost estimate covered a comparison between tubular frame and

flat panel

– Lower projected cost favored the flat panel

– Conclude that even with refinements to both designs that this conclusion would remain unchanged

• Flat panel costing– Proceeded to obtain additional cost information with modified

drawing set--solicited bids from 3 vendors

– Vendors were advised we were still refining the structural aspects and design changes must be anticipated

• Our objectives were to:– Break down costs for NRE, tooling materials, and fabrication labor

Frame Costs


ATLAS

• Analysis:– Must complete frame FEA to evaluate overall effect of frame light weighting

on performance, and support point reinforcement– Need to focus on panel joint designs and SCT support interactions with FEA – FEA of disk structure to include effects of mount

• Prototype frame– Need to decide on: end section material thickness, fiber choice, and core

material– Complete preliminary construction drawings, joint connections

• Costing– Solicited pricing information from 3 vendors to common definition

– Met with 3 vendors and discussed their proposal

– Selected lowest bidder and requested formal prototype quote• Fixed cost quote was based on performing effort in 3 phases• Prepared to go ahead with this effort-some discussion still pending

Where are We?


ATLAS

What is Needed to Finalize Frame Design

• Solidify Pixel/SCT interface to complete frame design and analysis– Insertion rail design envelop in sufficient detail

• frame attachments, method of transfer from rail to SCT, etc.

– Confirmation on SCT/Pixel mount interface- channel design?• structural robustness• dimensions, positional reference?• material

• Refinement to our proposed Pixel to SCT mount– Factor design into frame prototype testing

• Coolant line, manifold design, and cable routing– Develop understanding of possible extraneous loads on disk

assembly

– Recommend early prototype tests of tubing/manifolds to validate design of coolant system

• Heat shield effects??

Design Data


ATLAS

Outer Frame Development

• Decision on prototype core material------------------- 1/30/99

• Decision on fiber material---------------------------------- 2/19/99

• FEA of panel cut-outs complete------------------------- 2/28/99

• Release drawings for LBNL mock-up------------------ 1/30/99

• Order pre-preg material------------------------------------- 2/22/99

• Order core material------------------------------------------- 2/22/99

• FEA of reinforced corner (1st mode problem)-------- 3/30/99

• TVH with new environmental enclosure---------------- 3/01/99

• 1st sandwich panel-------------------------------------------- 5/15/99

• Evaluation of 1st panel without/with cutouts--------- 5/30/99

• Full scale prototype complete----------------------------- 9/15/99

• Preliminary stiffness tests complete-------------------- 10/15/99

Milestones


ATLAS

High Modulus Laminates(Cost on Bulk Basis)

Uncured Pre-preg PricingFiber

Resin

BryteTechnologies1

EX1515

YLA

RS-3

Hexcel(Fiberite)

954-315Msi Modulus Quasi-isotropic laminate

XN50 10#50#

$530/#$530/#

10#50#

$823/#$418/#

10#25#

$750/#$470/#

M55J 10#50#

$450/#$450/#

10#50#

$807/#$406/#

26Msi Modulus Quasi-isotropic laminateK13C2U 10#

50#$1175/#$1175/#

10#50#

$1407/#$848/#

1Indicated set-up charge of $1500. One should anticipate others will havesimilar charge

Frame Costs

ALLCOMP proposes P30 fiber carbonized/heat treated to equivalent 22 Msi, resin impregnated, as replacement to above resin based composites. At 25#, cost per lb is ~$500/#


ATLAS

Preliminary Cost Summary

Frame Costs

Item CompositeHorizons

PCI1,3 Allcomp1 AdvancedComposites1

Allcomp2 AdvancedComposites5

CompositeHorizons5

Central Panel Section $69,330 $57,349 $58,882 $41,281 $52,362 $95,010End Sections $58,721 $74,960 $42,653 $63,600 $75,205Central Corner Blocks $2,678 $14,668 $2,478 $9,260 $9381End Corner Blocks $2,678 $11,420 $2,478 $7,676 $4966Large Flange Mounting Disk $15,857 $24,840 $10,789 $19,809 $9,698 $36,291Small Flange Mounting Disk $15,857 $24,840 $10,789 $19,809 $9,698 $21,023

Total $164,428 $181,508 $126,030 $152,294 $241,876

Prototype End Section $38,920 $57,880 $30,816 $45,368 $48,9431XN50/Cyanate ester and honeycomb core2XN50/Cyanate ester and carbon foam, add $3000 for densification3Early bid response to drawings with less detail4 Includes all tooling required to build end and central section5XN50/carbon foam core


ATLAS

Sample Mass Breakdown for Frame Study

Item Framemass-kg

Addedmass-kg

Total mass-kg

%RL perframe

memberOuter center frame 1.219 1.219 0.23Outer End Frame 1.986 23.24 25.226 0.428End tubular members 0.085 0.085 0.37Longitudinal tubes 0.20 0.20 -End cone structure 0.30 0.30

Inner cone ring 0.12 9.92 10.04Outer barrel shell 0.46 0.46

total 4.37 33.16 37.53Solution for high modulus fiber with end frame and end beams at 0.6mm wall,center frame sandwich facing at 0.3mm

Mass Summary

atlas lbnl pixel support study 1 w.o. miller hytec atlas pixel detector support structure status and...

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