Modeling of the effect of Nb3Sn strand composition on thermal strains and superconducting performance

The effect of applied and thermal strain on the superconducting performance of Nb₃Sn strands is well known. Prediction of the strand performance depends on an accurate knowledge of the strand strain state. As well as operating strains due to mechanical loads on the conductor, the strand has a complex system of internal strains due to the fabrication process and partial annealing at the reaction heat treatment temperature (about 600 C). Nb₃Sn strands are now available with a range of different matrices around the superconducting filaments, varying both in mechanical properties and geometry. Starting from a database of mechanical properties, this paper will use finite element analysis to model the elasto-plastic behavior of the matrix, predicting the filament multi-axial strain state.