BaBar IFR Upgrades

1. BaBar IFR Upgrades An FEA Study of the Effects of Adding Brass Plates in the IFR LST Mechanical Design Review - SLAC

2. Present BaBar Configuration FEA (Finite Element Model) of BaBar As-built with Doors Off. LST Mechanical Design Review - SLAC

3. 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? LST Mechanical Design Review - SLAC

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

5. BaBar FEA Model J. Hodgson (SLAC) created a quarter-model of BaBar for the original BaBar structural analysis. LST Mechanical Design Review - SLAC

6. 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 LST Mechanical Design Review - SLAC

7. 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 LST Mechanical Design Review - SLAC

8. 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) LST Mechanical Design Review - SLAC

9. 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 LST Mechanical Design Review - SLAC

10. FEA Model 2 Consider von Mises stresses: – Max is 18 ksi (occurs on bolts attaching wedge to cradle) (units are in Pa) LST Mechanical Design Review - SLAC

11. FEA Model 2 Consider von Mises stresses without the wedge-cradle bolts: – Max range is ~ 10 ksi (units are in Pa) LST Mechanical Design Review - SLAC

12. 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) LST Mechanical Design Review - SLAC

13. FEA Model 3 - Deflections The bolt positions on the corner and gap plates are shown here. LST Mechanical Design Review - SLAC

14. 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 LST Mechanical Design Review - SLAC

15. 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. LST Mechanical Design Review - SLAC