Modelling the effect of twisting on electro-mechanical properties of Nb3Sn conductors

The influence of external loading on the superconducting filaments of Nb3Sn wires depends on the wire structure, for example, on twisting. Electro-mechanical behaviour of wires can be studied with finite element models. Three-dimensional models, whose numerical solution is heavy, are generally needed for twisted wires. However, this paper presents a two-dimensional model for twisted conductors that can be used under certain loading situations. Computational tests showed that twisting influences the superconducting properties significantly and must be modelled only if the ratio of the twist pitch to the distance between the outermost filament and the wire axis is smaller than 25.