pst prototyping september 2002

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ATLAS Pixel Detector

t. Stillwater LBNLSeptember 2002

PST PrototypingSeptember 2002

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Pixel Support Tube (PST) Overview

• Prototypes– Barrel Tubes– Forward Tubes– Heater Bonding

• Fabrication– Wrinkling- our nemisis– Flat Plate Compaction– 1D and 2D Wrapping

• Part Size Prediction– Discussion and results



Introduction to the Barrel and Forward Tube Prototypes

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Barrel Tubes

• 6 Ply QI Laminate– Possible 2 Hoop plies for

stiffness– Insulating Glass Mat inner layer– Heater co - bonded to outer

layer

• YSH-80 Carbon Fiber• Made using a steel mandrel

Heaters AL, Kapton0 (Optional) YSH-80 Carbon0 YSH-80 Carbon

60 YSH-80 Carbon-60 YSH-80 Carbon-60 YSH-80 Carbon60 YSH-80 Carbon

0 YSH-80 Carbon0 (Optional) YSH-80 Carbon

Mat Glass

6 ply quasi-Isotripic

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Forward Tubes

• 8 Ply Hybrid Laminate

– 2 extra Hoop plies are YSH-80 for stiffness

– Insulating Glass Mat inner layer

– Heater Co-bonded to outer layer

• YSH-80 Carbon Fiber / AQII Quartz

• Made using steel mandrel

– Can be ‘push’ released from mandrel

Heaters AL, Kapton0 YSH-80 Carbon0 YSH-80 Carbon

60 AQII Quartz-60 AQII Quartz-60 AQII Quartz60 AQII Quartz

0 YSH-80 Carbon0 YSH-80 Carbon

Mat Glass

8 ply Hybrid

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Heater Bonding

• Heaters can be Co-bonded directly to PST during cure

– The heaters can be applied individually or as a single hoop layer

– Heaters are shingled to provide a continuous aluminum EMI shield for the barrel



Prototype Fabrication Methods

Current and Future methods

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fabrication

• Barrel and Forward PSTs can both be made the same steel Mandrel– Greatly reduces cost of tooling– increases relative accuracy between PST sections

• Layers are compacted into sheets and then rolled by hand onto the mandrel– Minimizes hand error during layup of individual ply sections– Reduces chance of wrinkling due to uneven hand compaction

using only a roller or other tool

• A special jig may be used to facilitate alignment– Reduces the angle error during layup onto the mandrel– Increases reproducibility of a layup

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Common Mandrel

• The low CTE of the Forward Hybrid Layup makes it possible to use the same steel mandrel for Both the Barrel and Forward PSTs.

CTE µin/in-°KMandrel Steel 12.2Barrel PST (Hybrid 8 ply) 0.63Forward PST (Carbon 6 Ply) -0.3Old Forward (Quartz 6 ply) 14.71

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Jigs

• A swiveling arm can serve to align the compacted ply stack onto the mandrel.

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1D Ply Stacks – today’s method

• Multiple layers of Laminate are compacted onto a single stack using vacuum pressure.

– Removes trapped air– Joins layers into easy to handle

stacks– Reduces layup time– Facilitates alignment– Appropriate for 18” or smaller

PST

Layer 3

Layer 2

Layer 1

1/32” compaction gaps

Mandrel

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2D Ply Stacks – tomorrow’s method

• This Stacking method provides the most continuous fiber for a larger mandrel.

– Precision built into the stack during formation

– Simple wrapping method reduces errors

– Can be used for any length PST

0 degree

60 degree

-60 degree

-60 degree(2nd layer

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Wrinkling

• Wrinkling will only occur in certain conditions, and can be avoided by using certain fabrication methods

– Compacting each stack of plies flat, and then on the mandrel

– Rolling the ply stacks onto the mandrel under tension

– Using the common procedure of waiting until the laminate has reached flow temperature to pressurize the autoclave

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PST Diameters

Prediction and errors

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Prediction of PST Diameters

• TO predict PST Diameters one must know:

– CTEs of all involved materials• All known, measured, calculated,

or estimated

– Mandrel Diameters at room temperature

• Measured

– Laminate properties and thicknesses

• Calculated and Measured

– Gel temperature of Laminate• Known range

Chart of CTE for different fibers and heater designs using preliminary CN and Quartz Data

0

1

2

3

4

5

6

7

8

9

10

M55j M46j M35j YSH50 YSH80 CN60 CN80 Quartz

Fiber Material

CT

E (

pp

m/F

)

w/o 50um Glue, w 50um Al

w 50um Glue, w 50um Al

w/o 50um Glue, w 100um Al

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Calculated or Known CTEs for various Laminates and Materials used in Size Predictions

Barrel Shell YSH80 798 -1.6 QI 134 0.65 0.650Forward Shell (all glass) AQII 84 6.4 QI 23 14.71 0.650Forward Shell (hybrid) AQII/YSH80 84/798 6.4/-1.6 Axial 24 13.49 0.650Forward Shell (hybrid) AQII/YSH80 84/798 6.4/-1.6 Hoop 135 0.72 0.650Flanges/Mount Pads CN60 557.9 -1.49 QI 113 -0.17 N/A

Rails CN60 79.7 -1.49 Axial 111 -0.21 1.005Hoop Stiffeners CN60 79.7 -1.49 Hoop 132 -0.51 0.852Mount Flexures Titanium N/A N/A Isotropic 116 9.20 N/A

DirectionLaminate

E (GPa)Laminate CTE

(ppm/K)Thickness

(mm)Laminate Fiber Fiber E (GPa)

Fiber CTE (ppm/K)

Material CTE µin/in-°K

Mandrel Steel 12.26061 Aluminum 23.6

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Prediction of DiameterSimplified Example

• Prediction– Mandrel Diameter, CTEs, and Gel

temp are assumed Known.• Gel temp range is known so

calculation in performed for a variety of actual gel temperatures

– Mandrel O.D. at temperature is predicted

– Thickness of release layer is added– PST I.D. at temperature is inferred to

be the same– PST I.D. at room temperature is

predicted

• Measurement– PST O.D. and thickness are measured

• Error Measurement– Error is calculated as the difference

in predicted and measured I.D.

Mandrel Cold Mandrel HotTemperature ( C ) 27 121Diameter (in) 17.914 17.949

PST inner diameter Hot

PST inner diamter Cold

Temperature ( C ) 121 27Diameter (in) 17.949 17.950

Measured PST outer diameter

PST inner diamter

Temperature ( C ) 27 27Diameter (in) 17.990 17.949

ER

RO

RPrediction Error 0.001

PR

ED

ICT

ION

ME

AS

UR

EM

EN

T

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Average PST Diameter Absolute Error With Varying Gel Temperature Assumptions

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0.004

90 95 100 105 110 115 120 125

Degrees C

Av

era

ge

Dia

me

ter

Pre

dic

tio

n

Err

or

(in

)

PST Diameter Precision

• 13 Measurements were taken using this method– The results were

tabulated assuming 100, 110, or 121 degree gel temperature.

– Max average error: +/- 0.004 in (100 microns)

All Error Data:

Assumed Gel Temperature Mean Standard Deviation100 -0.0023 0.0028110 0.0002 0.0027121 0.0030 0.0030

Calculations in inches

pst prototyping september 2002

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