1. Present status of the flux return yoke design
Joint Institute for Nuclear Research
Present status of the flux return yoke design
A.Efremov, Yu.Lobanov, A.Makarov
Torino,

2. Magnet design

3. Yoke layout (new)
change in positions of the spacers in the forward door for better accommodation of the muon chambers
more thin axial bars (25x30 mm) between the barrel steel plates for more space for the muon counters
change in the screw attachment of the end caps to the barrel
absence of some connecting bars around the recesses in the upper barrel beam for insertion of muon panels

4. Support frame layout (new)
increased distance between I-form beams of the vertical and inclined bars of the frame for the better rigidity
increased dimensions of the plates coupling the I-form beams in the bars
decreased (by 160 mm) distance between the rails, according to the new bars thickness
inclusion of electric drive motors into the model

5. Support frame layout (new)
View from the below

6. TS layout (new)
Side view

7. TS layout (new)
Side view (detail)

8. TS layout (new)
Side view (detail)

9. Yoke cross-section
The door halves will be screwed to each other when they are closed
The end caps must be screwed to the barrel during the magnet movement
Free door opening: removal of spacers + deviation of direction by 1O (TT comment #2: spacers OK, why 1O ?)
The open doors are fixed in vertical position by the upper roller guide system (TT comment #2: why it is so massive?)
The free space should be left for access to the screws

10. Yoke and support front view

11. 2D FE model Analysis subject:
Cryostat and detectors weight application points
Iron yoke
(distributed gravity load)
The yoke weight is supported by the movable platform
Analysis subject:
deformation difference between different cases of support point positions (wheels, lifts and permanent supports)
deformation of the platform supporting the doors
Door gravity load points (when the doors are attached to the barrel during the magnet movement in the hall)
The door halves are fixed to each other

12. Deformations due to gravity: 2 points of support
Cryostat and detectors are supported by the upper barrel beam
Dy = -1.6 mm H X1 X2
Support point
DH = mm
DX1 = +1.2 mm
DX2 = +0.7 mm
The doors are supported by the side barrel beams

13. Deformations due to gravity: 4 points of support
Cryostat and detectors are supported by the upper barrel beam H X1 X2
Support points
DH = -1.6 mm
DX1 = +2.1 mm
DX2 = +1.1 mm
The doors are staying on the rails supported by the jacks

14. Deformations due to gravity: 6 points of support
Cryostat and detectors are supported by the upper barrel beam H X1 X2
Support points
DH = -1.5 mm
DX1 = +2.0 mm
DX2 = +1.0 mm
The doors are staying on the rails supported by the jacks

15. 3-D model
Positions of the screw connections

16. 3-D model Cryostat and detectors weight Magnetic pressure
Points of attachment to the frame displacement
The load case corresponds to 4+4 points of support

17. 3-D model View from Z-direction Cryostat and detectors weight
Magnetic pressure
Points of attachment to the frame displacement
The load case corresponds to 4+4 points of support

18. 3-D model Vertical deformations including the support frame
DY = -3.1 mm
DX = ± 1.2 mm
Without support frame: DY = -8.7 mm, DX = ± 4.8 mm

19. 3-D model
Vertical deformations along the line
DY = 0.09 mm

20. 3-D model
Vertical deformations along the line
DY = 0.23 mm

21. 3-D model
Vertical deformations along the line
DY = 0.08 mm

22. 3-D model
Vertical deformations along the line
DY = 0.27 mm

23. 3-D model
Horizontal deformations along the line
DX = 0.02 mm

24. 3-D model Upper barrel beam Axial magnetic force 227 kN
Magnetic pressure
Cryostat and detectors weight
Axial magnetic force 227 kN
Connection with the adjusting beam

25. 3-D model
Upper barrel beam
Axial magnetic force 227 kN

26. 3-D model Upper barrel beam Axial magnetic force 227 kN
Small contact areas

27. 3-D model
Upper barrel beam
Vertical displacements
DY = 0.44 mm

28. 3-D model
Upper barrel beam
Vertical displacements (detail)

29. 3-D model Upper barrel beam Buckling analysis 1-st mode n = 24.5
(safety margin)

30. 3-D model Upper barrel beam Buckling analysis 2-nd mode n = 27
(safety margin)

31. Summary
The relative deformations of the yoke during the movement in the framework of the considered concept of the platform (4 pairs of the railing wheels) are about 2 mm.
The deformations in 3D and 2D models do not differ much
The deformations for support systems with 4 or 6 jacks are almost equal
The suspension system for cryostat and detectors should be designed so that their positions would not critically depend on the yoke deformations
The change of the distance between the upper and lower barrel beams must be taken into account for design of the target pipe connecting the Target Production, IP and Target Recovery systems
In order to ensure the rails supporting the doors to be straight-line (for the unhindered door sliding), the supports for them in the experimental hall should be provided (in addition to the jacks supporting the main platform)
The contact area between the upper beam and the downstream door is small (the stress is 90 MPa), so increase of the recess in the beam is not allowable
Stability analysis of the magnet on the jacks, including seismic mode - ?