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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
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 ~ 0.8 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.
