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Communication Dans Un Congrès Année : 2010

Numerical Simulation of ITER Cable-in-conduit Conductors Mechanical Behavior

A. Devred
  • Fonction : Auteur
D. Ciazynski
  • Fonction : Auteur

Résumé

The ITER Cable-In-Conduit Conductors (CICC) are composed of an assembly of pure copper wires and composite superconducting strands (with embedded brittle Nb3Sn microfilaments) cabled together and inserted in a stainless steal jacket. If the current carrying capacities of individual ITER strands are clearly identified, by a dependence of the critical current on the applied strain and by a statistical quantification of possible microfilaments breakage, the characterization of cable-in-conduit is not yet fully achieved. What are the local strain values of strands inside CICCs under operating conditions is still an open question. A deeper understanding of how local strains develop and where critical strains appear in complex cabled structures could help to optimize CICCs designs in term of losses of conductivity. The present work aims at providing for a finite element model of CIC conductors, able to predict local strains, especially bending, at the scale of individual strands. The finite element software, MULTIFIL, initially developed to model various kinds of entangled media, has been adapted to consider the specific issues related to CIC conductors. The MULTIFIL's main feature is basically to handle the evolution of contact-friction interactions between wires. In this study, the initial conductors' geometry (trajectories of all individual wires), a priori unknown, is determined by a simulation of the shaping process by means of moving rigid tools. Starting from formed cables, both the thermal restraint and the transverse Lorentz loads are simulated through successive applications of proper loading. An important issue concerns proper boundary conditions to be applied at each strands ends. In that sense, the so-called pseudoperiodic boundary conditions, relevant to cable modelling, will be introduced. By the way, experimental and numerical “Force/Displacements” curves, obtained on cables under standard axial and transverse loading, show good agreement. A quantitative approach based on metallographic analysis of sub-cables and comparison of conductor's sections with numerical results will be presented as well. Results of full simulations (from initial shaping to magnetic loading) will be exposed for different conductors. Relevant information at the scale of strands (curvatures and strains distributions) can be retrieved from these simulations. The influence of changes in global design parameters (pitches lengths, void fraction and strands material properties) on local strains will be shown and discussed. This work is supported by CEA and ITER Organization allowing a helpful collaboration with ECP by contributing to the interpretation and providing for experimental database.
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Dates et versions

hal-00495175 , version 1 (25-06-2010)

Identifiants

  • HAL Id : hal-00495175 , version 1

Citer

Hugues Bajas, Damien Durville, A. Devred, D. Ciazynski. Numerical Simulation of ITER Cable-in-conduit Conductors Mechanical Behavior. ECCM 2010 - IV European Conference on Computational Mechanics, May 2010, Paris, France. ⟨hal-00495175⟩
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