Enhanced critical axial tensile strain limit of CORC^® wires: FEM and analytical modeling

Abstract

CORC® cables and wires are composed of spiraled HTS REBCO tapes, wound in multiple layers, and can carry very high currents in background magnetic fields of more than 20 T. They combine isotropic flexibility and high resilience to electromagnetic and thermal loads. The brittle nature of HTS tapes limits the maximum allowable axial tensile strain in superconducting cables. An intrinsic tensile strain above about 0.45% will introduce cracks in the REBCO layer of straight HTS tapes resulting in irreversible damage. The helical fashion at which the REBCO tapes are wound around the central core allows tapes to experience only a fraction of the total axial tensile strain applied to the CORC® wire. As a result, the critical strain limit of CORC® wires can be increased by a factor of more than 10 that of REBCO tapes. Finite element (FE) and analytical models are developed to predict the performance of CORC® wires under axial tensile strain. A parametric analysis is carried out by varying the winding angle, the Poisson’s ratio of the CORC® wire core, the core diameter, and the tape width. The results show that a small variation in winding angle can have a significant impact on the cable’s axial tensile strain tolerance. While the radial contraction of the helically wound tapes in a CORC® wire under axial tensile strain depends on its winding angle, it’s mostly driven by the Poisson’s ratio of the central core, affecting the tape strain state and thus its performance. Contact pressure from multiple layers within the CORC® wire also affects the CORC® wire performance. The FE model can be used to optimize the cable design for specific application conditions, resulting in an irreversible strain limit of CORC® cables and wires as high as 7%.

Investigating the effect of transverse compressive loads on the electromagnetic performance of superconducting CORC® cables

“…The work on CORC cables [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] is either treating the mechanical, electromagnetic, or critical transport characteristics, lacking a model so far that simultaneously handles mechanical and electromagnetic properties. Consequently, a 3D numerical model of the CORC cable is established based on the T-A formulation and the FE method.…”

“…The mechanical and electromagnetic response of CORC cables has attracted significant attention because of their importance for magnet design and optimization [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Anvar et al [8] presented finite element (FE) modeling of the stressstrain state of CORC cables and wires under bending loads.…”

DC Electro-Magneto-Mechanical Characterization of 2G HTS Tapes for Superconducting Cable in Magnet System Using Artificial Neural Networks

“…UPERCONDUCTING technology is generally very promising for being used for applications in power systems, aviation industry, and healthcare sector in devices such as magnetic resonance imaging/nuclear magnetic resonance magnets [1]- [5], High Temperature Superconducting (HTS) cables [6]- [8], superconducting machines [9], [10], superconducting fault current limiters [11], [12], superconducting magnetic energy storage units [13], [14], and HTS transformers [15], [16]. In superconducting magnets, as one of the most successfully commercialised applications of superconductors, low temperature superconducting wires and This manuscript was received 04 May 2022, revised 10 July 2022, accepted 22 July 2022.…”

“…Yazdani-Asrami, and W. Song, are with Propulsion, Electrification & Superconductivity group, Autonomous Systems & Connectivity division, James Watt School of Engineering, University of Glasgow, Glasgow, G12 Figure 1. Twisting of HTS tapes in form of CORC cables in HTS magnets, figures adapted from [2]- [5]. also HTS tapes and cables are used in the form of coils to generate the required magnetic field with required properties [17], [18].…”

“…As shown in Figure 1, usually in magnet applications, HTS tapes and cables are twisted to build up the coils and the magnet systems [2]- [5]. Twisting of HTS tapes causes local critical current density (Jc) reduction and stress increase.…”