1 / 26

Stress and cool-down analysis of the cryomodule

Stress and cool-down analysis of the cryomodule. Yun He MLC external review October 03, 2012. Outline. Structural analysis Weight of module and its sub-assemblies Deformation/stress/frequency of HGRP under beamline weight

nakesha
Télécharger la présentation

Stress and cool-down analysis of the cryomodule

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Stress and cool-down analysisof the cryomodule Yun He MLC external review October 03, 2012

  2. Outline • Structural analysis • Weight of module and its sub-assemblies • Deformation/stress/frequency of HGRP under beamline weight • Deformation/stress/buckling of vacuum vessel under coldmass weight & vacuum • Stress on cavity flexible support due to differential thermal contractions • Cool-down thermal analysis • Asymmetric cooling on 40K shield • Material properties as a function of temperatures • 40K thermal shield temperature/stress during cool-down • Heat loads from conduction and radiation • Heat loads from conduction and radiation on posts and shield • Heatinleakfrom conduction through warm-cold transition beampipes Yun HE, MLC External Review

  3. Structural analysis • Weight of module and its sub-assemblies • Deformation/stress/frequency of HGRP under beamline weight • Deformation/stress/buckling of vacuum vessel under coldmass weight & vacuum • Stress on cavity flexible support due to differential thermal contractions Yun HE, MLC External Review

  4. Weight of module and its sub-assemblies Cold mass 3 Ton Cryomodule 7 Ton

  5. Outline of structural analysis • Deformation/stress of HGRP under 1 ton beamline weight • Material: Ti grade 2, Ф 0.28 m ID x 9.5 mm wall x 9.65 m L • Deformation/stress of vacuum vessel under 3 ton cold mass weight & vacuum • Material: Carbon steel, Ф 0.96 m ID x 9.5 mm wall x 9.15 m L • LHe vessel cooled faster than HGRP, causing differential thermal contraction • Material: Ti grade 2 Yun HE, MLC External Review

  6. Structural analysis of HGRP Deformation and natural frequency Max. 0.1 mm displacement Natural frequency ~ 89.1 Hz > 60 Hz • Conclusion: • Acceptable vertical displacement • May use shims to compensate the different vertical displacement at various locations • Vibration safe; may add stiffening rings if needed Yun HE, MLC External Review

  7. Structural analysis of HGRP Stresses • Material yield strength: • 276 MPa @room temperature • 834 MPa @cryo temperature • Conclusion: • Plenty safety margin Max. stress: 26 MPa Yun HE, MLC External Review

  8. Structural analysis of vacuum vessel Deformation Cross-section of top ports Right port Middle port Left port • Max vertical displacement : 0.38 mm • Adjustment on suspension brackets will compensate these vertical displacements Yun HE, MLC External Review

  9. Structural analysis of vacuum vessel Deformation before/after pump-down Before pump-down After pump-down (1 atm external pressure applied) • Change in vertical position after pump-down would cause cavity to shift horizontally by 0.3 mm Yun HE, MLC External Review

  10. Structural analysis of vacuum vessel Buckling analysis Pre-stress from structural analysis (3 ton load + 1 atm external pressure) 1st mode deformation Critical load for the onset of buckling: 6.2 X applied loads So, buckling unlikely - safe Yun HE, MLC External Review

  11. Cavity flexible support model, boundary conditions Weightforce of 20 kg cavity shared by 2 supports A: FZ=100 N B: ΔZ=0 C: ΔY=1 mm Fixed top surface on HGRP Displacement caused by 300K to 2K temperature differential between cavity and HGRP, though it is an unlikely case In reality, cool-down is well controlled to maintain temperature differential less than 20 K, see Eric’s talk Displacement under different temperature differentials/ranges between cavity and HGRP Thermal expansion rate of Ti Yun HE, MLC External Review

  12. Cavity flexible support sensitivity check of stress vs. cool-down rate Max stress 460 MPa, caused by 1 mm displacement • In reality, the temperature differentials are controlled within 20K, hence the stress would be much lower • At low temperature • Differential displacement small • Yield strength high Case studies of stresses under different temperature differentials/ranges between cavity and HGRP Yun HE, MLC External Review

  13. Cavity flexible support stress @ normal operations Vertical displacement caused by weight of cavity <0.001 mm Max stress caused by weight of cavity Yun HE, MLC External Review

  14. Cool-down thermal analysis • Asymmetric cooling on 40K shield • Material properties as a function of temperatures • 40K thermal shield temperature/stress during cool-down Yun HE, MLC External Review

  15. Cool-down analysis of 40K shield Model & thermal interfaces • He gas cooling being on one side causes thermal gradient and shield distortion • He gas cooling rate 4 K/hr for normal cool-down procedure • Simulate: • With a cooling rate of 4K/hr • Temperature profile • Thermo-mechanical stresses and distortion • Scenario w/ faster cool-down rate @20K/hr Conduction 300K He gas Radiation from 300K He gas Yun HE, MLC External Review

  16. Material properties as a function of temperature Used material data from NIST for calculations Yun HE, MLC External Review

  17. Cool-down analysis of thermal shield Boundary conditions @ steady state 1.25 W/m2radiation flux rate from room temperature @ steady state Experimental data from CERN Heat transfer coefficient 1100 W/m2-K of He gas in extruded pipe @ steady state 1 W/panel (over-estimated) heat load from semi-rigid cables SS 304L G10 Al 6061 T6 Cu OFHC Al 1100-H14 5K Ti grade 2 Yun HE, MLC External Review

  18. Cool-down analysis of 40K shield Boundary conditions for transient analysis Radiation heat flux rate set differently in 3 zones depends on their temperatures with a lapse of time delay - colder, top/bottom, far end He gas heat transfer coefficient is a function of temperature, hence a function of time Yun HE, MLC External Review

  19. Cool-down analysis of 40K shield Temperature distributions and trends Temperature @15hr, when temperature gradient reaches max. ∆T=13oC, for a duration of ~30 hrs Temperature @75hr, when temperature reaches equilibrium, ∆T=3oC Max. ∆T=55 oC @7 hr Yun HE, MLC External Review

  20. Cool-down analysis of 40K shield Deformation @15hr Temperature profile @15hr was loaded Y axis X axis Z axis Yun HE, MLC External Review

  21. Cool-down analysis of 40K shield Stress @15hr Max. von-Mises stress 45 MPa @ fingers Max. shear stress 30 MPa @ fingers Conclusion: Shield safe for normal cool-down operations Material strength Yun HE, MLC External Review

  22. Cool-down analysis of 40K shield Stress @faster cooldown rate 20K/hr • Prototype testing • Accidental faster cool-down Max. 60 MPa @ finger corners, safe Conclusion: Shield safe still safe Yun HE, MLC External Review

  23. Heat loads from conduction and radiation • Heat loads from conduction and radiation on posts and shield • Heat inleak from conduction through warm-cold transition beampipes Yun HE, MLC External Review

  24. Heat transfer from room temperature • Conduction via G10 tube • Radiation from 300K to 40K shield Conduction 300K Radiation G-10 tube 40K 5K 2K Yun HE, MLC External Review

  25. Heat loads @ steady state Heat loads on middle section, 1/3 of the shield Compared with ENS’s back-of-the envelope calculation 1.569 W/cm @300K-40K 5K 6.5K Yun HE, MLC External Review

  26. Beamline warm-cold transitions for prototype – Heat inleaks Gate valves will be at 80 K Warm-cold transition, wall 1.65mm Will have sliding joints on beamline outside module to accommodate beamline shifts at cold 300K 300K 80K 80K Heat leak from 300K to 80K: 1.3 W Heat leak from 300K to 80K: 5 W Yun HE, MLC External Review

More Related