Failure Assessments for MQXF Magnet Support Structure with a Graded Approach

Journal Article · 29 March 2019 · IEEE Transactions on Applied Superconductivity

DOI: https://doi.org/10.1109/TASC.2019.2908113 · OSTI ID:1498548

Pan, Heng  ^[1]; Anderssen, Eric C.  ^[1]; Cheng, Daniel W.  ^[1]; Prestemon, Soren O.  ^[1]; Ambrosio, Giorgio  ^[2]

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1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

© 2002-2011 IEEE. The high luminosity large hadron collider (LHC) upgrade requires new quadrupoles, MQXF, to replace the present LHC inner triplet magnets. The MQXFA magnet is the first prototype that has a 150-mm aperture and uses Nb3Sn superconducting technology in a 4.2-m magnetic length structure. The support structure design of the MQXFA magnet is based on the bladder-and-key technology, where a relatively low pre-stress at room temperature is increased to the final preload targets during the cool-down by the differential thermal contraction of the various components. The magnet support structure components experience different load levels from pre-load to cool-down and excitation. Consequently, a few parts experience high stresses that may cause localized plastic deformations or internal fracture development. The concept presented in this paper for the failure assessment of support structures integrates nonlinear finite-element (FE) analysis with detailed sub-models and fracture mechanics into an advanced engineering tool. The nonlinear FE solutions enable estimations of the structural response to the given loads, and the advanced fracture analysis with failure assessment diagram assesses the structure safety index of results obtained from the FE model. The paper describes how the MQXFA end-shell segments are being optimized based on the failure analyses.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Contributing Organization: LARP
• Grant/Contract Number: AC02-07CH11359; AC02-05CH11231
• OSTI ID: 1498548
• Alternate ID(s): OSTI ID: 1604694
• Report Number(s): FERMILAB-PUB-19-057-TD; 1724042
• Journal Information: IEEE Transactions on Applied Superconductivity, Vol. 29, Issue 5; ISSN 1051-8223
• Publisher: Institute of Electrical and Electronics Engineers (IEEE)Copyright Statement
• Country of Publication: United States
• Language: English