Pure bending strains of Nb3Sn wires

This paper presents in detail recent pure bending strain investigations of ITER Nb3Sn wires including a pure bending device development, bending effects on the critical currents and their model analyses. The pure bending test device allows applying a uniform bending over a large range of bending strain on a strand sample under a large electromagnetic Lorentz force. Pure bending characteristics of five different Nb3Sn wires including three internal tin and two bronze wires were tested and evaluated with a newly developed integrated model that accounts for neutral axis shift, current transfer length, mechanical filament breakage and uniaxial strain release due to the applied bending load.