Homogenisation methods for the thermo-mechanical analysis of Nb3Sn strand

Daniela P. Boso, Marek Lefik, Bernhard A. Schrefler

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

An accurate estimation of the strain state of a strand inside a coil is a crucial point in the prediction of Nb3Sn conductor performance, since Nb3Sn based strands show a strain-dependence of their critical parameters. To perform a numerical analysis of a superconducting coil it would be impossible to operate a spatial discretization fine enough to take into consideration each single material. Therefore, we make use of homogenisation methods, so that the strand (or the triplet or higher order bundles) can be schematized as an equivalent homogeneous material. This paper presents a general overview of different ways to approach a study of superconducting strands using homogenisation techniques. We aim to point out that there is not a "unique best approach", but different methods have to be chosen depending upon the microstructure of the strand. Three kinds of strands are taken into consideration to exemplify the various techniques: the strand from European Advanced Superconductors (EAS), from Furukawa (FUR) and from Outu Kumpu (OUK) company. For the three strands the thermal strain due to the cool-down from reaction temperature to the coil operating conditions is calculated, making use of the effective properties obtained via the various approaches.

Original languageEnglish (US)
Pages (from-to)569-580
Number of pages12
JournalCryogenics
Volume46
Issue number6
DOIs
StatePublished - Jun 2006

Keywords

  • Finite element technique
  • Multifilament superconducting strand
  • Multiscale modelling
  • Self-consistent and asymptotic homogenisation
  • Thermal strain

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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