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Communication Dans Un Congrès Année : 2011

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

Résumé

In order to assess the local strains at the scale of the strands responsible for the degradations of the electrical performances, a global modeling of the mechanical behavior of CICCs from their initial forming to the application of magnetic loading is proposed by means of finite element simulation. A simulation code dedicated to the modeling of entangled media is adapted to handle with the specific loadings of CICCs operating conditions. In the proposed approach, each wire of the studied conductor sample is modelled using a kinematically enriched beam model and contact-friction interactions between wires are detected and accounted for. Particular pseudo-periodic conditions have been developed to prescribe appropriate boundary conditions at the ends of the cable. Contact conditions with moving rigid tools are considered to model the initial forming of the conductor and the presence of the jacket during the application of loadings. The global problem is solved using an implicit solver. The simulation is used first to determine the initial geometry of the conductor. A theoretical configuration where all wires are described by helicoidal functions corresponding to the different cabling stages is deformed and compacted by rigid tools into a cylindrical or petal-shape form to get the initial configuration. An elastoplastic behavior is considered in the axial direction of strands. A transverse orthotropic elastic model is used in the transverse directions to attempt to reproduce the plastic deformation due to the pinching of the strand. The material properties are identified upon experimental data from the tests of single Nb3Sn strands and OFHC copper wires. The validation of the cable model in both the axial and the transverse directions will be presented with comparison of the loading curves to experimental measurements. The different stages experienced by CICCs during their service life, namely the annealing induced by the heat treatment, the axial compression generated during cooldown by the differential of thermal expansion with the jacket and the application of magnetic Lorentz forces are successively simulated on the ITER CS and TF conductors (considering one petal). Analysis of the local axial strains demonstrates a high nonuniformity, with combination of bending and axial compression at the local scale. The influence of changes in the design parameters (twist pitches, void fractions and material properties) on local strains will be discussed.
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Dates et versions

hal-00648418 , version 1 (05-12-2011)

Identifiants

  • HAL Id : hal-00648418 , version 1

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Hugues Bajas, Damien Durville. Numerical Simulation of the Mechanical Behavior of the ITER Cable-in-conduit Conductors. 22nd International Conference on Magnet Technology, Sep 2011, Marseille, France. ⟨hal-00648418⟩
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