Pixel Support Tube Interfaces

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ATLAS

Pixel Detector

Pixel Support Tube Interfaces

LBNL Internal PST Review

E. Anderssen, LBNL

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Overview


Structures and Position in ATLAS


Internal Interfaces


Rail Geometry/Sliders/Roller


Pixel to PST Mounts


PP1/PP0


Mount/External Interfaces


PIXEL to SCT Mount Block


Forward End Support Flexures

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

PST Key Structures

Hoop Hat Stiffeners

(section view)

30

45

10

SCT Flexures

and mount pads

Forward End Flexures

PST Flanges

PP1 End Plug

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Pixel Package

Internal Interfaces

PP0

PP1

PP1

Beam pipe Support

Rail Sliders

Beam pipe Support

Rail Sliders

Pixel Frame

Rollers

Pixel Mounts

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Package interfaces to PST


Package has Several Physical Interfaces to PST


Rail Sliders/Rollers on Frame and Service/Beampipe
Support


Pixel Mount Blocks


PP1 End Plate


Installation Configuration


Frame Rollers engaged, Pixel Mounts not Yet Engaged


Rails Supports Entire Detector


PP1 Fixed Portion Clears Internal Dimensions of PST


Installed Configuration


Frame Rollers Disengaged, Pixel Mounts engaged


Rails Continue to support Services and Beampipe


PP1(s) are Supported By PST end Flanges

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Inner Detector Layout

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Patch Panel Zero

PPO region preliminary layout

cable routing and
assembly sequence not completed

Nominal routing for tubes shown here

allows access to
rails and pixel supports (discussed later)

Pixel Mount Block Access

Frame Rollers

Service Sliders

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Patch Panel One

PP1 layout determines final
length of the Forward
section of the PST

Layout of
region is preliminary, and will
require physical modeling to
complete

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Mount Interfaces and Geometry


Pixel detector is supported on mounts integrated into
Flange of the Barrel PST


Barrel PST is mounted to the Barrel SCT via Flexures
and fixed Support


Mount Pad integrated with Flange of Barrel PST directly
couples SCT and Pixels decoupling as much as possible the
shell of the PST


Forward PST sections are mounted to the Barrel PST
via a flange, and supported at their ends from the PST
Support structure (formerly Beampipe support)


Rails discussed later, however for completeness:


Pixel Detector rides in with package on rails and transitions
to mounts in the Barrel section of the PST


Remainder of Package (Service/Beampipe support Structure)
remains on rails

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Mount Schematic


Pixel Support Tube Mounts to SCT Interface Block Via a Flexure


Pixel Detector Mounts to PST Barrel Via the Pixel Mount


SCT Not shown here

Pixel Detector

SCT Interface Block

Pixel Mount

Flexure

Missing Integrated Model with both
PST and Pixel Detector Frame

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Interface to SCT Interlink

(Barrel PST support)


Pixel Support Tube is supported by Three Flexures and One
³)L[HG?6XSSRUW´


All Flexures and the Fixed Support have identical bolted and
pinned interfaces with PST Barrel and SCT Interface Block


Interface Blocks which penetrate the SCT Thermal
Enclosure are mounted to the SCT Interlink


All Interface Blocks are identical


Brief modification of the end of the interlink to accommodate


Penetration through SCT Barrel Thermal enclosure
standardized

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Proposal for SCT
-

Pixel Interface

-

4 Blocks fastened to the SCT horizontal interlinks

-

Adjustement, if needed, by shimming or machining PST blocks



Dimension

Is OK

Slide of E. Perrin

Need to Make integrated
Model/Interface Drawing
with relevant parts of SCT

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

SCT Inner thermal enclosure

-

I propose to fix the TE inner cylinder directly to Barrel 3


-

To save space.


-

To try to simplify penetrations and sealing.


Flexure

PST BARREL MOUNT PAD

3mm Shim (0
-
6mm As REQ)

R240

R253.5

Z 780

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Manufacturing and Assembly implications


Flexures Mount Directly to SCT Interface Block (prior
to PST Insertion)


Mounting Pixel Support Tube requires access to inside
of Barrel PST


Pins and bolts into Flexure are accessed through cutout


“Adjustment” is by shimming (horizontal) and flexure
replacement (vertical)


Adjustment only required in emergency in pit

nominally PST
is centered in SCT


Above implies that set of pre
-
machined flexures will be
required


Pinned interfaces require accurate mating and
alignment of interfaces


Proposed solution is to Bond PST mount Pads in place


Depending on Schedule either Transfer Tooling or Bond in
place


ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Manufacturing Accuracy by Bonding


Whether SCT or Mistress tool is used depends on
Schedule


Bond Gap can currently account for +/
-

200
m
, but can
easily accommodate up to 1mm if required (need to
change some nominal dimensions)

Bond Between Mount Block and

PST Mount Pad can be made last

Mistress tool or SCT AS Built

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Interface Geometry

780

803

PST Mount

Flexure

253.5

SCT Barrel 3

And Interlink

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Mount Block Analysis


Flexures chosen for tight packaging Accurate
manufacture and predictability of analysis


Large Factors of Safety against yield at maximum
foreseen loads


Have assumed that loads from Integrated SCT/PST
model represent worst case loads (2mm end
deflections of PST)

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

How Much Float is needed


Fixed Point to End of SCT
yields an internal stress


Due to CTE mismatch on the
order of 1
-
2ppm/C


Fixed point to end of
Cryostat yields an
External load on the ID
Barrel via the SCT


There is potentially a large
CTE mismatch between
Cryostat and the Pixel
Support Tube


Case where Cryostat raised
10C above no
-
power
condition, and where
Support tube CTE is
unusually high (>1ppm/C)


Flexures need to assure
minimal loads at these
extensions yet remain stiff
in the orthogonal
directions


fixed

1.6m


120
m

4.25m @ +1ppm/C

2.65m @ +1ppm/C

4.25m @ +23ppm/C


1.2mm

2.65m @ +23ppm/C



700
m

-
20C

-
20C

+30C

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Barrel Flexure Analysis

0.5
m
/N

0.17
m
/N

2.3
m
/N

50N

147N

150N

75
m

25
m

115
m

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Needed Load Set on Flexure

F
x

F
z

F
y

M
y

M
z

M
x

Direction

Load

Required

Limit

Load

Fx

121N


450N

(~250
m
)

Fy

211N

2.3kN

Fz

68N

400
m

( 150N)*

Mx

322N.m

750Nm

My

189N.M

24.6Nm

Mz

53N.m

19.6Nm

*Load at 400
m

deflection

stop prevents further travel preventing plastic
deformation of flexure. Load then transfers to bolted joint which has a limit load

Equal to F
y
.


No limit in Fy foreseen due to high factor of Safety


Limits in X,Z make FoS similar to Fy (bolted interface)

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Design of flexure against Failure


Flexure Yields in Z
-

Travel at ~400
m

deflection


Stops included to limit travel to 400
m

or less


Fy Ultimate for Flexure depends on Tensile stress
area of Webs on Flexures


Area of webs ~20mm
2



area of Bolt M6 ~20mm
2


Fx will have limits built into interface pads as
shown in figure above on right


Built Prototype Flexure without Stops to verify
plastic limits


Will test Stiffness of Flexure with TVH system

F
y
=5.2kLbf

F
X

F
x

F
z

F
y

M
y

M
z

M
x

Flexure

PST Mount PAD

Limit to

<150
m

Shim

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Forward Flexure

Plastic Limit stop will be incorporated in design, and integrated with

Flex lock mechanism necessary for lock
-
out during Installation of

Pixel Detector

80

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Pixel Support Condition on PST


This is an attempt at a pseudo
-
kinematic mount
condition


Three points are fixed, with one adjustable in height
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Mounts will be adjusted in co
-
planarity to match mount
surfaces
²
reducing twist of frame

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Pixel Frame Mounts


Prototype of Pixel mounts
developed


Axle and Bearing design
refined


Angular contact bearings


Ceramic race


Ceramic Balls


Titanium Shaft


Contact analysis shows one
ball can take full detector
load (no brinnelling)


Statistical tolerance
analysis shows 5 or more
balls in contact


Shaft is Full Hard 6Al4V Ti
alloy with Nitrided Surface

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Interface to Pixel Frame Endplate


Three mounts fixed, One adjustable vertically


Two dowel pins, Three mounting screws


Holes machined in Ears of Endplate


Endplate registered to End frame by tight
shoulder screws in same ear

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Pixel Mount Block and preload spring

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Preload Flexure


Flexure Designed for 105N
Preload


Nominally equals detector
mass plus some margin


Deflection at preload
nominally 1mm


Large compliance allows for
moderate machining and
misalignment tolerances


Factor of Safety against
yield at Max flex design
travel 1.7

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Flexure

PST BARREL MOUNT PAD

R240

SCT Interface surface

pixel

40
m

Budget

Mount Deflection Budget


Gravity Deflection Budget of 40
m

is assumed

80Hz assumed for
vibrational stability


Flexure/Mount Pad
-
Flange/Pixel mount all contribute


Assumed 20
m

for Pixel mount, 20
m

for rest

ATLAS

Pixel Detector

September 2002

Internal Review

E. Anderssen LBNL

Deflection of Mounts


Tip deflection of Long
Shaft is 20
m
.


Angle change of shaft
from pillow block adds
8
m
.


Nominal budget for Pixel
mount was 20
m
.


Long shaft is coupled with
short PST interface block


Short shaft has less shaft
deflection but more PST
Pad windup


Total Budget of 40
m

between SCT and Pixels is
shared between these
mounts and the PST mount
pad


Total budget is close to
met
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