Bending of CORC^® cables and wires: finite element parametric study and experimental validation

Abstract

A CORC ® cable is composed of several layers of helically wound high-temperature superconducting (HTS) tapes on a round core with the winding direction reversed in each successive layer. The cable is flexible but the flexibility is limited by the critical strain value causing breakage of the HTS layer when this strain level is exceeded. The cables for magnets in fusion reactors experience large mechanical and electromagnetic loads. These loads arise from the cabling, coil manufacturing, cooling, and magnet operation. In order to optimize the manufacture and operating conditions, the mechanical behavior of CORC ® cables must be understood for the different relevant loading conditions. The cable configuration with many contact interactions between tapes and the non-linear behavior of the materials during the production and operating conditions makes the modeling challenging. Detailed finite element (FE) modeling is required to account for these complexities. The FE modeling allows an accurate calculation of the stress-strain state of the cable components under various loads and avoids time-consuming large-scale experimental optimization studies. This work presents a detailed FE modeling of the 3D stress-strain state in a CORC ® wire under bending load. The elastic-plastic properties of the individual tape composite materials and its temperature dependence are taken into account. The FE model is experimentally validated by a multi-layer CORC ® bending test performed by Advanced Conductor Technologies LLC. A critical intrinsic tensile strain value of 0.45% is taken as the threshold where the individual tape performance becomes irreversibly degraded. The proposed FE model describes the bending test of the CORC ® wire adequately and thus can be used to study other types of loads. A parametric study is ongoing with dependent variables to pursue a further optimization of CORC ® cables and wires for various applications.

Retraction: Cutter design and multi-objective optimization of machine for cable peeling

“…Cable processing technology has attracted much attention. Peeling, straightening (Gui et al, 2019;Wang et al, 2018;, bending (Anvar et al, 2018;Phocas et al, 2019;Yu et al, 2019) and other processes of the cable are required before using or forming the product. Figure 1 shows a product of cablesthe lower lead of a double pole variable fuse.…”

Development and performance of a 2.9 Tesla dipole magnet using high-temperature superconducting CORC® wires

“…However, there is still a significant gap between state-of-the-art and the required CORC ® wire performance for a REBCO CCT insert magnet [48]. A possible path towards achieving the target performance in CORC ® wires is to develop thinner and narrower REBCO tapes [49] and to improve their transport performance at relevant field and 4.2 K [10].…”

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].…”