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Cryo -Module Thermal Analysis

Explore thermal and vibration effects in cryo-module bellows causing cracks at the center. Analysis of bowing, deflection, and separation under varying conditions to prevent failure.

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Cryo -Module Thermal Analysis

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  1. Cryo-Module Thermal Analysis Vishy Ravindranath Dt: 05/18/2018

  2. Introduction • Questions: • What caused cracks only in the center (4 & 5) cavity bellows • Thermal + Vibration: • Thermal Bowing (tensile stresses in the center bellows) • Vibration

  3. Boundary Conditions- Thermal Vac Vessel + End Caps cools down to -10 F HGRP at 60 F Top of Vacuum Vessel at 40 F Bottom of Vacuum Vessel at 60 F

  4. Boundary Conditions- Thermal Vac Vessel + End Caps warms up to 80 F HGRP at 60 F

  5. CASE 1: Vac Vessel + End Cap cooldown to 10F and HGRP at 60F Vac Vessel + End Caps cools down to -10 F Check: ∆Y = 12 (μm/m-˚C) x 12 (m) x 45 (̊C) Shrinkage/End ~ 3.2 mm HGRP at 60 F Contraction of the Vacuum Vessel in the Long. Dir. Contraction of the Vacuum Vessel in the Vertical Dir.

  6. Case 1: Boundary Conditions for the HGRP 0.5 mm Frictionless Contact for the Vertical Bolts on the End Posts 3 mm 0.5 mm 3 mm Frictional Contacts for all other bolts (Fric. Coeff. = 0.2) Volume of HGRP pipe is 0.06 m^3 The assumed density of 52,000 kg/m^3 gives 3000 kg for the cold mass

  7. Case 1: Defection of the HGRP Pipe Vertical Deflection in the HGRP The Deflection of the HGRP at the Coupler 4 & 5 location is negligible 0.5 mm vertical deflection @ coupler 6 location ? Bellow Failure Location

  8. CASE 2:Thermal Gradient (∆T = 20 F) Top to Bottom in the Vacuum Vessel Vertical Deflection Plot Temperature Plot 1 mm bowing in the center

  9. CASE 3: Vac Vessel + End Cap warmup to 80F and HGRP at 60F Vac Vessel + End Caps warms up to 80 F HGRP at 60 F ~ 1 mm separation at both ends

  10. Vibration- FREE FREE ENDS The weight of cryomodule is obtained by using a very high density (52,000 kg/m^3) for the HGRP pipe 1st mode of vibration = Rocking Motion FEA Calculated frequency = 9 Hz

  11. Summary • FEA qualitatively shows: • Thermal deflections from uniform heating/cooling are negligible • Significant bowing of the vacuum vessel/HGRP pipe would require a large thermal gradient (~20 F assumed for the analysis) from top to bottom. Large thermal gradient unlikely due to slow cool down? • Relative thermal expansion between the vacuum vessel and the HGRP will weaken the end clamp constraint

  12. Back-Up

  13. Boundary Conditions-Matl End Caps HGRP Stainless Steel

  14. Boundary Conditions-Displacement Boundary Conditions Fixed Point in the Y direction Half model considered (symmetry assumed) to reduce computational time. The vacuum vessel supports are clamped to the shipping frame. It is assumed that the temperature change in the vacuum vessel and shipping frame are similar. The vacuum vessel is free to expand along the Y axis

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