Finite-Element Analysis of the Strain Distribution Due to Bending in a REBCO Coated Conductor for Canted Cosine Theta Dipole Magnet Applications

Abstract

Finite-element analysis of the strain distribution due to bending in a REBCO coated conductor for canted cosine theta dipole magnet applications Permalink https://escholarship.org/uc/item/760535cn Journal IEEE Transactions on Applied Superconductivity, 29 (5) Abstract-High-current cables using REBCO tapes can be used to develop high-field dipole magnets. However, the strain accumulated during cable fabrication and coil winding may reduce the critical current of the conductor. Therefore, it is important to properly consider the strain when designing high-field magnets. In this work, we used structural finite element analysis to predict the strain experienced by a REBCO tape during bending in configurations relevant to the fabrication of high field accelerator magnets, in particular, the mechanical strain generated during cable fabrication and winding in a canted-cosθ (CCT) dipole configuration.We considered two different cable options: (A) flat tape that lay in the mandrel channel and (B) a REBCO tape helically wound around a circular copper core, the typical configuration of the conductor in round core cable (CORC®). Strain accumulated during tape winding is studied for different core diameters and winding tilt angles. FEA longitudinal strain results were compared with the simulations for configuration A, where higher strain was observed experimentally. Configuration B was verified indirectly by comparing experimentally measured Ic with the one predicted (based on the longitudinal strain) as function of the bending diameter. Good agreement was found up to a bending diameter of 30 mm. The presented results will help to understand the impact of bending on REBCO tapes and CORC ® wires to develop high-field magnets. Index Terms-High-temperature superconductors, yttrium barium copper oxide, superconducting cables, superconducting magnets This is the author's version of an article that has been published in this journal. Changes were made to this version by the publisher prior to publication.The final version of record is available at http://dx.

Impact of local geometrical irregularities on critical currents of REBCO tapes in round cables

“…To understand how the mechanical loading affects the electrical properties of SC tapes, we began our study with Finite Element numerical modelling [10,13,21,22] using the Workbench module of software ANSYS ® Multiphysics Campus, Release 2020 R1. We built multiple models, which are presented in this Section.…”

Dipole Magnets above 20 Tesla: Research Needs for a Path via High-Temperature Superconducting REBCO Conductors

“…Conductors with a high aspect ratio such as the Roebel cable can minimize the strain in REBCO layers by following the constant-perimeter principle for magnet design and conductor bending [100][101][102][103][104]. From this aspect, round REBCO conductors are more flexible and can work with diverse magnet designs, although to understand the critical current degradation and reduce the strain development is still critical [30,[105][106][107][108][109][110].…”

“…Understanding how strain develops in REBCO layer during the cabling and magnet winding processes will be critical [32,104,106,[108][109][110]195,196]. The design tools based on the understanding of the conductor mechanics will help guide the development of more flexible round REBCO conductors and the optimized REBCO tapes with thinner substrates and narrower widths [34,38,160].…”

“…Although one can make CCT magnets using stacked-tapes or Roebel cables [104,110], we focus on round conductors that are under active development in the U.S. [31,34,38]. With multiple layers of tapes wrapped helically around a round former, the tapes are transposed within each layer.…”

“…The measured strain dependence can be used to understand the transport performance of REBCO tapes under bending that is required for the fabrication of multi-tape conductors and magnets. Towards this goal, we develop numerical models based on a developable surface [104] and finite-element analysis [110] to analyze the strain distribution in REBCO tapes. The experimental results and computational tools can provide useful input for the design of robust REBCO conductors and magnets that can benefit both high energy physics and fusion applications.…”