# Presentation: 056163

## PST Design UpdatePST CDRoctober 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 pads

- End Plugs (1 mm equiv. carbon sheet)

- Hoop Hat Stiffeners
- (section view)

- 30

- 45

- 10

- End Support

- End Supports

## Support Tube – Flange Details

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

- barrel

- forward

- Constraint Areas

## Flange Bolt Spacing Calculations

- Flange 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)

## Flange Bolt Spacing Calculations (cont.)

- Forward Tube

**Barrel tube**
**Assumed rigid**

- Forward
- And services
- mass

- 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

- tube
- Deflection ( )

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

- d

- L

## Support Flange Bonded Assembly

- Flange Face (machined layup)

- Flange base
- (Layup)

- Stiffeners
- (layups)

- T-nuts
- (bonded)

## 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—all
- Tube Supports are
- Horizontal and Co-planar

- Properties TBD

- Constraint TBD

- Support Positions are shown,
- But constraint conditions are
- Not indicated here.

## Constraint Conditions: Fixed/Free ends

- Fixed Forward Ends
- (Applies to all analysis cases)

- Free Forward Ends
- (Applies to most analysis cases)

## Model Properties

## PST Analyses

## Baseline Model

- PEEK Flanges
- Longitudinal Ribs

## Carbon Flange Material

- Carbon Flanges
- Longitudinal Ribs

## Removing Ribs

- No Longitudinal Ribs

## Vibration Results Summary

## Modal Shapes

- Hoops and End Plugs

- New Flange Shape

- Barrel Constraints

- Modes: 119 / 119 / 124 / 124

## Low Stiffness Forwards

- Additional Hoops

## Reaction Loads On SCT

- Vertical Bending – Both Ends

- Horizontal Bending

## Gravity Sag Calculations

** **

- DY = .57 mm

- DY = 1.6 mm

- Carbon

- Glass

## Comparison to SCT Analyses

**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

## Testing

**Friction Tester**
- 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)

## Prototyping Plans

**Sample 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**
- Extra Prototype Step??

## Plans For Near Future

**Import SCT Model into current analyses**
- Double check SCT loads – ascertain acceptability
- Determine pixel stability with reduced stiffnesses
**Fabricate sample tube sections (1 foot lengths)**
**Analyze mounts/end constraints/service interactions**
- Eric Anderssen’s presentation