atlas pixel detector october 2001 pixel week n. hartman lbnl 1 pst design update pst cdr october...

October 2001Pixel Week N. Hartman LBNL 1

ATLAS Pixel Detector

PST Design UpdatePST CDRoctober 2001



Current Design Status• FEA Modeling

– Design Variables– Recent Analysis Results– Low Stiffness Forwards– SCT Reaction Loads– Comparison to SCT analysis

• Testing– Friction Tester Constructed– Slider Materials Delivered– Carbon Samples Ordered

• Prototyping Plans– One Foot Sample Mandrel will be fabricated– Initial Autoclave Tryout Run Will Be Completed Soon– Mandrel Quotes Received



Design Variables

• Flange Material (PEEK or Carbon Fiber)• Longitudinal Ribs• Hoop Stiffeners (in Forwards)• End Plug (PP1 panel)• Flange Shape• Barrel Constraints (ties across SCT diameter)• Service Mass (incorporated in forward shell material)• Fiberglass Forward Shells• 1 or 2 Z Constraints• Forward End Constraints



PST Model



FEA Model – Important Features

Bolt flanges

Sct mount padsEnd Plugs (1 mm equiv. carbon sheet)

Hoop Hat Stiffeners(section view)

30

4510

End Support

End Supports



Support Tube – Flange Details

Flange x-section detail

End view of barrel flange(forward flanges have no Mount bosses and no gas seal features – see below)

barrelforward

Constraint Areas



Flange Bolt Spacing CalculationsFlange is conservatively modeled as a simple beam:

- modeled as guided beam with length of bolt spacing/2- cross section is assumed to be smallest flange section (forward)- flange force given by support tube loads (next slide)

L

L/2

Flange Load

Number of Bolts Bolt Spacing (m) Delta (microns)32 0.046 11.4540 0.037 5.8648 0.031 3.3956 0.026 2.1464 0.023 1.43



Flange Bolt Spacing Calculations (cont.)

Forward TubeBarrel tubeAssumed rigid

ForwardAnd servicesmass

Flange load=(Forward Load*(L/d))

Tube Deflection is calculated based on following assumptions:- forward tube pivots rigidly about bottom of flange- total forward tube mass (including services) is cantilevered- full flange load is taken by upper bolts only (3 bolts)- all structures rigid

Frequency is estimated based on tube deflection using f=(1/2 * (g/)1/2)

Flange delta

tubeDeflection

( )

Number of Bolts Delta Tube (microns) Frequency32 64.55 62.6440 33.05 87.5548 19.13 115.0856 12.04 145.0264 8.07 177.18

desire frequency > 100 Hznumber at left assumes no ribs -ribs act like bolt constraints -evenly spaced ribs allow half the number of boltsDesign for 24 bolts in flange

d

L



Flange Face (machined layup)

Flange base(Layup)

Stiffeners(layups)

Support Flange Bonded Assembly

T-nuts(bonded)

Old design - now gone forindependent thermal barrier



PST Boundary Conditions



PST Position in Inner Detector

PIXEL SUPPORT TUBE

SCT

TRT

ID Vee Rail

ID Flat Rail

Side C Side A

View from top—allTube Supports are

Horizontal and Co-planar

Properties TBD

Constraint TBD

Support Positions are shown,But constraint conditions areNot indicated here.

+Z

+X

+Y Vertical

Agreed Support Positions outside PST

PST Support Conditions Under Investigation



Constraint Conditions: Fixed/Free ends

Side C Barrel Side a

Side C Barrel Side a

Fixed X

Fixed XYZ

Fixed Z

Fixed Y

Fixed Forward Ends

Free Forward Ends

+Z

+X

+Y Vertical



Model Properties

Material Model Material Location

Fiber Modulus (GPa)

Bulk Modulus (GPa)

Density(kg/m3)

High Mod. Carbon

Shell, Hat Stiffeners

420 98 1650

Ultra High Mod. Carbon

Flanges(Option 1)

560 126 1650

PEEK (graphite filled)

Flanges(Option 2)

N/A 3.5 1500

Glass (Quartz) Forward Shells 91 21 1800

HM Carbon (incl. service mass)

Forward Shells 420 98 12300

Glass (incl. service mass)

Forward Shells 91 21 12450



PST Analyses



Original Model

Side C Barrel Side aSide C Barrel Side a

ModelDescription Mode 1 Mode 2 Mode 3 Mode 4 Mode 1 Mode 2 Mode 3 Mode 4

Original Model 8.9 11.9 17.9 26 12.9 13.7 18 42.1Carbon Flange Material 24.5 41.2 61.5 65.6 54.7 55.6 69.9 72.8

Without Ribs 25.8 44 55.9 62.4 58.5 59.2 67.9 68.5With Hoops and End Plugs 64 114.6 116.5 117.9

Carbon Flange Concept 31.4 48.4 55.3 62.2 88.7 118.6 119 123.6Barrel Constr. Across SCT 51.3 53.8 55.3 62.2 118.8 119 123.6 123.7

Service Mass (13 kg) 26.4 27.7 28.6 32.3 53.1 53.2 54.2 54.2Glass Shells – 1 Hoop 27.4 27.4 27.8 27.9

Glass Shells – 3 Hoops 43.7 43.7 43.8 43.8

Free Forwards Fixed Forwards

Modes in Italics are shells modes , Modes in bold are beam (cantilever) modes.

PEEK Flanges

Longitudinal Ribs



Carbon Flange Material










Carbon Flanges

Longitudinal Ribs



Removing Ribs










No Longitudinal Ribs

PST Rib Comparisons Area (mm^2) Inertia (mm^4) PST Tube 726 1.93E+07

PST Ribs (6) 360 1.92E+07 Tube + Ribs 1086 3.85E+07



Constrain across SCT












Modal Shapes

Hoops and End Plugs New Flange Shape

Barrel Constraints

Modes: 119 / 119 / 124 / 124



Low Stiffness Forwards

Model Fixed Forwards

Description Mode 1 Mode 2 Mode 3 Mode 4

Carbon Shells – 1 Hoop 53.1 53.2 54.2 54.2 Glass Shells – 1 Hoop 27.4 27.4 27.8 27.9 Glass Shells – 3 Hoops 43.7 43.7 43.8 43.8

Additional Hoops



Vibration Results Summary











Reaction Loads On SCT

Model Material FX (N)

FY (N)

FZ (N)

MX (Nm)

MY (Nm)

MZ (Nm)

Carbon - 151 0 253 - -

Glass - 53 0 89 - -

Vertical Bending – Both Ends

Both Ends Bent – 1 Z ConstraintModel Material FX (N) FY (N) FZ (N) MX

(Nm)MY

(Nm)MZ

(Nm)

Carbon 146 - - - 233 -

Glass 52 - - - 83 -Both Ends Bent – 2 Z Constraints

Model Material FX (N) FY (N) FZ (N) MX (Nm)

MY (Nm)

MZ (Nm)

Carbon 297 - 1870 - 536 -

Glass 108 - 468 - 110 -

One End Bent – 1 Z ConstraintModel Material FX (N) FY (N) FZ (N) MX

(Nm)MY

(Nm)MZ

(Nm)

Carbon 390 - - - 623 -

Glass 137 - - - 218 -

Horizontal Bending



Gravity Sag Calculations

Carbon Glass



Comparison to SCT AnalysesSCT Analysis Comparisons

Bend Direction

Load Case FX (N) FY (N) FZ (N)

Y dy1 = dy2 = 2 mm SCT 141 Y dy1 = dy2 = 2 mm Carbon 151 Y dy1 = dy2 = 2 mm Glass 53 Y dy1 = dy2 = 2 mm Projected* 49

X dx1 = dx2 = 2mm SCT^ 325 588 X dx1 = dx2 = 2mm Carbon^ 297 1870 X dx1 = dx2 = 2mm Glass^ 108 468 X dx1 = dx2 = 2mm Projected*^ 118 147

Force Load Case DY (mm)

G Carbon .57 G SCT Carbon .61 G Glass 1.64 G SCT Glass 2.88

• Discrepancies Due To:– Properties (SCT used different tube modulus; barrel modulus and

forward modulus changed to glass)– Loads (pixel detector distributed, not supported on mounts)– Constraints

• Extra Z constraint• SCT intrinsic compliance• Simple instead of complete constraints at Barrel

Projected uses ratioof SCT to our FEA with carbon forward tubes



Slider design - materials testing

• Friction Tester nearing completion– Applies variable pressure– Measures angular acceleration– Slides sample against interchangeable disk of given material

M

slider to be tested

turntable (carbon disk)

position is movable along arm

M

Mass provides normal force

Encoder on shaft measures acceleration

arm hinge

G



Materials to Be Tested

• Sliding Materials– PEEK

• Glass Filled• Virgin

– Vespel• Moly-Disulfide Filled• Virgin

– PPS• Teflon, Carbon, glass, moly-disulfide filled• Probably not viable

• Substrates– Carbon fiber disks (prospective material and Layup)

• 420 GPa Fiber• 8 Ply Quasi-iso layup• 437 micron thickness

– Non-Woven glass mat on surface (some samples)• Work just starting. No conclusions. May investigate roller

depending upon results



Prototyping Plans

• Short Mandrel– 1 foot long - 1 for glass, 1 for carbon – aluminum or steel– “Dry-run” in autoclave to determine thermal response– Determine final diameters from test layups

• Full Size Mandrel (forward length)– Quotes already received

• Approximately 14,000 to 20,000 USD• 8 Weeks delivery

– Plans to Fabricate forward prototype in glass• All flanges and rail features• Use for production forwards if diameters are correct

• Implications of Glass Forwards/Carbon Barrel on prototyping plans must be assessed



Plans For Near Future

• Import SCT Model into current analyses– Double check SCT loads – ascertain acceptability– Determine pixel stability with reduced stiffnesses

• Begin detailed design of flanges and tubes• Fabricate sample tube sections (1 foot

lengths)• Analyze mounts/end constraints/service

interactions– Eric Anderssen’s presentation

atlas pixel detector october 2001 pixel week n. hartman lbnl 1 pst design update pst cdr october...

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