October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

BaBar IFR Upgrades

An FEA Study of the Effects of Adding Brass Plates in the IFR

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

Present BaBar Configuration

FEA (Finite Element Model) of BaBar As-built with Doors Off.

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

The Problem

• Removal of the gap and forward corner plates provides clear access to components in the barrel.

• Will removal of the gap and corner plates deform the barrel to the point that the gap and corner plates could not be re-assembled?

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

Analysis

• Determine with Finite Element Analysis (FEA) whether the deformation of the barrel will affect the re-assembly of the gap and corner plates.

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

BaBar FEA Model

J. Hodgson (SLAC) created a quarter-model of BaBar for the original BaBar structural analysis.

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

New FEA Model - #1As-built

Present Loads:

•Solenoid (14000 kg) – 4 points inside lower side plates

•DIRC (8000 kg) – 14 points from the top & bottom gap plates & on 100 & 50-mm IFR plates

•Calorimeter (30000 kg) – 4 pts. at outside of mid-plane corner plates

•Flux bars (8000 kg) – at each corner

•No end plug weight here

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

New FEA Model - #2Upgrade Configuration

Upgrade Configuration Loads:

•Solenoid (14000 kg) – 4 points inside lower side plates

•DIRC (8000 kg) – 14 points from the top & bottom gap plates & on 100 & 50-mm IFR plates

•Calorimeter (30000 kg) – 2 pts. on bwd. end on outside of mid-plane corner plates and 6 pts. on fwd. end on earthquake wide flange supports

•Flux bars (8000 kg) – at each corner

•No end plug weight here

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

New FEA Model - #2Upgrade Configuration

Consider the following extreme scenario:

•All Forward corner plates are removed

•Top & bottom gap plates on Forward end are removed

•Top & bottom gap plates on Backward end are left on

•All other center gap plates are removed (were not part of original model)

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

New FEA Model - #2Upgrade Configuration

Brass loading:

•Six layers of brass plate segments are installed in all sections

•Layers 5, 7, 9, 11, 13, 15

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

FEA Model 2Consider von Mises stresses:

– Max is 18 ksi (occurs on bolts attaching wedge to cradle)

(units are in Pa)

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

FEA Model 2Consider von Mises stresses without the wedge-cradle bolts:

– Max range is ~ 10 ksi

(units are in Pa)

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

FEA Model 3 - Deflections• Model 3 = Model 2 (Upgrade) – Model 1 (As-built)

• Consider the relative change in position by comparing the vector sum of x,y,z nodal deflections

• Max overall relative change in position is less than 0.3 mm in the area of the wedge-cradle bolts

units are in (m)

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

FEA Model 3 - Deflections

The bolt positions on the corner and gap plates are shown here.

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

FEA Model 3 - Deflections

• Now consider only the nodal points on the x-y plane of bolt holes for corner plates and the ends of the side plates

– Fwd end: max change in relative position is ~ 0.2 mm

– Bwd end: max change in relative position is ~ 0.3 mm

October 21, 2003 LST Mechanical Design Review - SLAC N. Yu

Results

• Results suggest that the maximum relative movement of the bolt holes and internal component support points on the side plates on the Forward End is ~ 0.3 mm.

• This also suggests that preliminary results from a year ago are correct:

Removal of the gap and forward corner plates to gain access to barrel components

seems like a viable option.