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Published byPercival Barber Modified over 9 years ago
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D. Passarelli, M. Merio, L. Ristori, B. Wands March 13, 2012
Technical Division SRF Department ASME design on SSR1 G3 2010 ASME Boiler and Pressure Code section VIII, Division 2 β Part 5 Design by analysis methodology Material properties Design Load parameter Protection against plastic collapse βCoarseβ results Protection against collapse from buckling Protection against local failure Protection against failure from cyclic loading D. Passarelli, M. Merio, L. Ristori, B. Wands March 13, 2012
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Conceptual Design of dressed SSR1 SRF cavity with Tuner
Transition ring (under developing) Bellows Helium Vessel SS316L Cavity Nb Lever Tuner π πππ£ =25 ππ ππ ππ ππ =540 ππ»π§ ππ ππ ππ β0 Β±10 π»π§ π‘πππ ππ ππ =β0.7 π π΅π +4.9 Brazed-joint: Beam pipes Coupler port Side ring
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2010 ASME Boiler and Pressure Code VIII Division 2 β Part 5
According to the ES&H Fermilab manual, the Cavity and Helium Vessel can be considered a pressure vessel and it must comply with the β2010 ASME Boiler and Pressure Vessel Codeβ. Among the various options provided by the code, we decided to follow the Design-by-Analysis methodology described in the β2010 ASME Boiler and Pressure Vessel Code section VIII, Division 2 β Part 5β. Division 1: formulas, simple shape, typically thicker walls Division 2: complex shape, FEM analysis Requirement: achieve the desired Maximum Allowable Working Pressure (MAWP) ππ΄ππβ₯2 πππ at room temperature (293K) ππ΄ππβ₯4 πππ at cryogenic temperature (2K)
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2010 ASME Boiler and Pressure Code VIII Division 2 β Part 5
The Design-by-Analysis methodology utilizes the results from finite element analysis to assure: Protection against plastic collapse avoid unbounded displacement in each cross-section of the structure due to the plastic hinge Elastic stress analysis method Elastic-plastic stress analysis method Protection against collapse from buckling buckling is characterized by a sudden failure of a structural member subjected to highΒ compressive stress, where the actual compressive stress at the point of failure is less than the ultimate compressive stresses that the material is capable of withstanding. Elastic-plastic stress analysis Protection against local failure (i.e. joints) Elastic analysis Elastic-plastic analysis Protection against failure from cyclic loading Elastic ratcheting analysis method
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Material properties The main parts of the Helium Vessel and Cavity are made in SS316L and Niobium, respectively. To describe the material model required to perform the different kind of analysis, by finite element software, the following mechanical and thermal properties for both materials are needed. Mechanical properties (at 293K and at 2K): Linear Elastic properties (E, Ξ½) elastic-plastic curve Niobium by FESHM Chapter Dressed Niobium SRF Cavity Pressure Safety.pdf and ER10163-SRF_Cavities_Spec SS316L by β2010 ASME Boiler and Pressure Vessel Code section II, Part Dβ Thermal properties: coefficient thermal expansion (CTE) curve from 293K to 2K.
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Design Load parameter SSR1 load conditions
The relevant loads acting on the SSR1 dressed cavity are: βPβ pressure in the helium space under fault condition βPsβ static head from liquid Helium βDβ dead weight of the system βTβ cooldown from 293K to 2K βTβ controlled axial displacement of 0.25mm at the Beam Pipe (βtuningβ operation) For each analysis the code provides the load combination and factored load cases
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Design-by-Analysis Scheme
MAWP β₯2 πππ at 293K β₯4 πππ at 2K Protection against collapse from buckling Elastic plastic stress analysis method Protection against failure from ratcheting Elastic stress analysis method Protection against plastic collapse Elastic stress analysis method Load combination P+Ps+D β material 293K Condition to satisfy: π ππ β€S Elastic plastic stress analysis method Global Criteria_1 2.4(P+Ps+D) β material 293K Global Criteria_2 2.1(P+Ps+D+T) β material 2K Condition to satisfy: Convergence of the analysis Result Map of critical zones on the model βCoarseβ result 293K: 2K: 3 bar (TbC) Protection against local failure
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Protection against plastic collapse Elastic stress analysis - @ 293K and 2bar
Elastic material T=293K Load combination applied: P+Ps+D P = 2 bar Refined mesh Condition to satisfy: π ππ β€S π ππ =25 πππ π ππ316πΏ =100 πππ 200 MPa 50 MPa Away from the point of singularities the stresses are under the limit
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Protection against plastic collapse Elastic stress analysis - @ 4K and 4 bar
Elastic material T=4K Load combination applied: P+Ps+D P = 4 bar Refined mesh Condition to satisfy: π ππ β€S π ππ =200 πππ π ππ316πΏ =390 πππ 200 MPa 390 MPa Away from the point of singularities the stresses are under the limit
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Protection against plastic collapse Elastic plastic stress analysis - @ 293K
Elastic plastic material T=293K Load combination applied: 2.4(P+Ps+D) βCoarseβ mesh Pressure of last solutionβ¦β¦β¦5.35bar ππ΄ππ = =2.23πππ
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Simulation under study
Protection against plastic collapse Elastic plastic stress analysis 4K Elastic plastic material T=4K Load combination applied: 2.1(P+Ps+D+T) βCoarseβ mesh Pressure of last solutionβ¦β¦β¦6.3bar ππ΄ππ = =3πππ (not finalized results) Simulation under study
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Conclusion We have defined a procedure to check the mechanical performances of the dressed SSR1 cavity in agreement with βES&H Fermilab manualβ and β2010 ASME Boiler and Pressure Vessel Codeβ. The simulations to assure the protection against plastic collapse are running and the first βcoarseβ results are encouraging. In 15 days we should be able to show more finalized results. THANKS!
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