Strain distributions in superconducting strands with twisted filaments

The aim of this article is to analyze the strain distributions of filament bundles in the superconducting strands subjected to external mechanical loads and thermal strain. A multistage micromechanical model is adopted to characterize the mechanical behavior of the superconducting strand with twisted filaments. First, we employ the equivalent model to simplify the filament bundles. Then, the continuous filament bundles are divided into discrete elements, and an incremental mean-field micromechanics theme based on the Mori-Tanaka method is used to obtain the equivalent properties of the strand and the local strains in the Nb3Sn filament bundles. The results for two different structures are compared. The variation trends of normal strains along x, y and z directions are different. The effects of temperature on the equivalent properties of strands are discussed.