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HALLD TAGGER MAGNET STRUCTURAL ANALYSIS

Pole Plate analysis Vacuum chamber analysis Vacuum chamber tie rods and brackets. HALLD TAGGER MAGNET STRUCTURAL ANALYSIS. Minimize fastener count (machining) and confirm that they meet the load sequence requirements. Confirm that plate deformation (and gaps!) are minimal.

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HALLD TAGGER MAGNET STRUCTURAL ANALYSIS

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  1. Pole Plate analysis • Vacuum chamber analysis • Vacuum chamber tie rods and brackets HALLD TAGGER MAGNETSTRUCTURAL ANALYSIS Presented by William Crahen 6/10/09

  2. Minimize fastener count (machining) and confirm that they meet the load sequence requirements. • Confirm that plate deformation (and gaps!) are minimal. • Check that tapped holes in 1006 will not strip, or distort to the point they create a problem. POLE PLATE ANALYSIS gap Non-parallel Poles Presented by William Crahen 6/10/09

  3. Top plate 12” FASTENERS 24” 1 ¼” Grade 8 bolt to prevent pole bending Upper pole plate ¾” rod threaded both ends- 11L17 or high strength allthread 1 ¼” Grade 8 bolt to help compress O-ring. ½”-13 threaded rod Grade 8 equiv. to compress O-ring and prevent bowing of the vacuum chamber. 2” 4140 HT ROD THREADED BOTH ENDS 2-4.5. Bottom plate Lower pole plate Presented by William Crahen 6/10/09

  4. Ignore contribution of 28 threaded rods 11 bolts to compress O-ring PULLING THE UPPER POLE DOWNCOMPRESSING THE O-RING Pivot point 34” 15” Preload these bolts to twice this= 32680 lbf, which is 32% of proof load for 1 ¼” bolt of grade 8 specification. 79300# @ 35% squeeze Presented by William Crahen 6/10/09

  5. Ignore contribution of 11 bolts and O-ring force. 25” 31.6” 47.3” 21 rods 2” dia. 2” MAIN TIE ROD FORCES Pivot point 3.1” 15.1” For equilibrium: For specification (.5*proof): Weight of upper plates= 82054 Inner and outer tie rods carry 5500 lbf. There are 8 upper brackets. Mag and vac force on pole face=312861 lbf 12.9” Vacuum load from edge of chamber (does not include O-ring force)=2388 lbf * 7 locations=16716 lbf <<2388 value from Ansys. Presented by William Crahen 6/10/09

  6. 24” 32688 131250 These forces actually repeat every 31”,not 24”- therefore this adds a safety factor. 32688 Note: 24” is ~1/10th total plate length 131250 gravity FEA using specified forces: Loads note: this is not the total load seen by the four ½”-13 tie rods. They also carry an O-ring compression force=4812, and a preload of 2000, for a total of 9200 lbf carried by the four tie rods. 5500 5500 32688 2388 Magnetic and vacuum force:312861 Presented by William Crahen 6/10/09

  7. Note: The Glasgow University analysis predicted about twice this deformation- I have more confidence in my analysis. FEA using specified forces: Deformations Manufacturing tolerance equal to +/-.005” exceeds this! Presented by William Crahen 6/10/09

  8. Noise level- machining tolerance issues 100 times greater. FEA using specified forces: Deformations Presented by William Crahen 6/10/09

  9. Ansys reported zero gap. This is penetration . Once again, surface motion is insignificant with respect to flatness. FEA using specified forces: Deformations Presented by William Crahen 6/10/09

  10. Stress in tapped holes in the 1006 Plates: Length of engagement=2*D. Plate made of bubble gum- thread inserts all around? Presented by William Crahen 6/10/09

  11. We plan to use thread inserts , but what length of engagement would carry the load without them? Presented by William Crahen 6/10/09

  12. Reality check on equations for As and An:A simplified look at shear area. Presented by William Crahen 6/10/09

  13. Calculation of tensile and shear areas I will use the reality check value, as it is the smallest. Presented by William Crahen 6/10/09

  14. Thread load capacity of 1006 Plates and vacuum chamber attachments: Both of these fasteners can be threaded into the vacuum chamber under no load, then held stationary while hardened nuts at the other end apply the load. As the working load is much lower (5500# for ¾, and 2300# for the ½), and friction is not an issue, no inserts are needed. Bolts securing vacuum chamber bracket to the plates are preloaded to 6500#. Inserts not needed, but will be used in any case. Preload=32,688, but frictional forces from tightening are also significant. Insert needed. Presented by William Crahen 6/10/09

  15. Minimize the motion of the O-ring in contact with the poles • Minimize the change in the opening width of the thin window flange to ~2mm • Look at the overall plate motion and confirm that it isn’t much more than 2mm. • Confirm that the stresses are acceptable • Look at the effect of adding additional tie rods VACUUM CHAMBER ANALYSIS Presented by William Crahen 6/10/09

  16. Minimize the motion of the O-ring in contact with the poles • Minimize the change in the opening width of the thin window flange to ~2mm • Look at the overall plate motion and confirm that it isn’t much more than 2mm. • Confirm that the stresses are acceptable • Look at the effect of adding additional tie rods VACUUM CHAMBER ANALYSIS Presented by William Crahen 6/10/09

  17. 3/8” O-ring Original configuration of the pole flange Outer tie rods The O-ring was modeled as six linear springs to get a fair approximation of it’s loads, and added to the vacuum load. The midspan deflection was ~0.029”, even though outer tie rods were present. this seemed like an unacceptably large movement of a critical seal. Presented by William Crahen 6/10/09

  18. O-ring motion reduced to ~.008”. We can now consider reducing the size of the O-ring from 3/8” to ¼”. The solution was to add the ½”-13 tie rods to the edge of the flange: Presented by William Crahen 6/10/09

  19. The original design: The thin window flange had to much movement- the ‘C’ ribs were not stiff enough to limit the change in the opening width to 2mm. Motion of single flange! The lower flange also moves upward. Presented by William Crahen 6/10/09

  20. BRUTE FORCE SOLUTION- DOUBLE THE AREA MOMENT OF INERTIA FOR THE RIBS. Diameter=18.5” Presented by William Crahen 6/10/09

  21. CHANGE IN OPENING WIDTH=.018+.051=.069”=1.75mm RESULTANT SKELETON DEFLECTION: Difference in values caused by gravity. Its effect is the difference from the average=.016” Presented by William Crahen 6/10/09

  22. RESULTANT PLATE MOTION: Plates close together= .034+.062=.096”=2.4mm Presented by William Crahen 6/10/09

  23. Ansys ‘hiccup’-presumably a small mesh problem. VON-MISES STRESSES: Plate stresses well below the 16,700 psi limit as per ASME Boiler and Pressure vessel code Presented by William Crahen 6/10/09

  24. Corner stress concentrator will yield locally. VON-MISES STRESSES: The structural skeleton is also comfortably below the 16,700 psi pressure vessel limit for 316L. Bogus stress here- edge attachment of tie rod Presented by William Crahen 6/10/09

  25. 20% DIFFERENCE. REALITY CHECK ON ANSYS DEFLECTION: 0.085” Presented by William Crahen 6/10/09

  26. DEFLECTION=.027+.059=.086=2.2mm. Diagonal only buys us .43mm. TIE ROD HERE? PROBABLY NOT. ADD A DIAGONAL TIE ROD? Presented by William Crahen 6/10/09

  27. Look at the total bracket /tie rod deformation and stress. • If the tie rod deformation is a significant portion, beef it up to reduce this. • Modify the bracket as needed to reduce it’s total motion to ~0.5mm. BRACKET/TIE ROD ANALYSIS Presented by William Crahen 6/10/09

  28. ORIGIONAL BRACKET (8” x 4” x 3/8”wall): Rigid body tube motion (plate motion) Tube bending .0036” rod stretch- not worth improving. Presented by William Crahen 6/10/09

  29. New bracket (10” x 4” x ½” with center bolt): Bolt added inside tube holds plate flatter. Big improvement from .030” Presented by William Crahen 6/10/09

  30. Loads applied to bracket: 8X 6500# 13799 x 1.077=14861#, and our preload is only 6500#. We still plan to use thread inserts here. 5500# Presented by William Crahen 6/10/09

  31. Bracket stress: Presented by William Crahen 6/10/09

  32. Summary: • The pole deflection is on the order of achievable machining tolerance, and gaps induced by bending are essentially zero. • The fasteners and tapped holes have been appropriately sized to prevent tensile failure and thread stripping. • The Vacuum chamber design meets the deflection criteria, stress levels are lower than allowed by ASME Pressure vessel code, and the critical O-ring seal will experience acceptable variation in “squeeze” (~.008”). Presented by William Crahen 6/10/09

  33. Remaining tasks: • Investigate reducing the size of the O-rings from 3/8” to ¼” • Analyze the coil attachments • Analyze the thin window • Analyze the Weldment that supports the main plates Presented by William Crahen 6/10/09

  34. Additonal slides: Presented by William Crahen 6/10/09

  35. CENTER OF GRAVITY OF CHAMBER: Presented by William Crahen 6/10/09

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