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Update #2
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Europe/Zurich
Description
Featuring Michael Guinchard
Attendees: Emma Gautheron, Michael Guinchard, Ariel Haziot, Marco Masci, Diego Perini
Roland Piccin, Oscar Sacristian de Frutos, Davide Tommasini, Gianluca Vernassa
Comments on context description
- Title of the topic: "Nb3Sn coils: mechanical characterization and modelling"
- Issue (less aggressive): In some magnets, degradation occurs at computed global stresses below the limit, in other magnets, no degradation are observed at computed stress higher than the limit.
- Residual stresses after reaction: there is a dedicated line in HFM for this topic, Cedric Garion
- Objective: Improve modeling of the behavior of the coil during the life steps of a magnet (assembly, reaction, cooldown, powering) looking for a description that relies on properties measured on dedicated samples .
Models
- Description of the evolution of the model from MQXF to 11T (2019) and 11T (2021).
- A strain/stress curve not including sitting effect is used for validation.
- Previous models are validated with stress only in the transversal direction. Little attention has been paid to model the behavior in the other directions.
- Incoherence are found with model 2021 while going from 3D to 2D.
- 12T today is still juggling between the BISO and MISO or another one not defined yet.
Tests to make toward a standardized 10-stack
- Understand which version of the keystoned stack is more representative of the non-keystoned stack (reference).
- Check the difference between global and local measurements on the exact same sample (displacement of the UTM crosshead combined with DIC).
- Check the influence of the length of the sample on the measurement.
- Check the distribution of stress as a function of the sample configuration using DIC.
- Check influence of load on CTE (experimental set-up to be designed)
- Test could be done with 11T/SMC cable or with MQXF/Flat-MQXF cable. The advantage of using the second one is that it gives us results on future 12T as well.
Considerations
- Michael: The fabrication of the samples should be documented carefully for the next 10-stacks to be made.
- Davide: How could we get the stress inside the sample and not at the interface? Adequate simulations must support this work.
- Diego: Manufacture the molds (reaction and impregnation) for all cables as soon as possible. Don't be shy !
Actions list
- Ariel and Gianluca prepare a test plan to asses the questions raised above
- Ariel launches the design/fabrication of moulds for MQXF and RMM
- Ariel launches the fabrication of 11T/SMC 10 stacks.
- Gather ideas on how to measure CTE as a function of load.
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