The axial tensile stress-strain characterization of Ag-Sheathed Bi2212 round wire

The stress distribution generated by the differences in the thermal expansion and the electromagnetic load is the driving factor for the transport properties of Bi2212 superconducting round wire (RW). The effort on studying the impact of strain on the transport properties is increasing, in terms of the axial and transverse stiffness of the RW. Consequently, the experimental stress-strain data are required at the RW level for accurate modeling, analysis and eventually for optimizing cable design and manufacture. In this paper, the axial tensile measurements on Bi2212 RWs and component materials (Ag and Ag/Mg alloy) have been performed at room temperature, 77 K and 4.2 K, respectively. Comparing with LTS strand (e.g., Nb₃Sn and NbTi) , the stiffness of Bi2212 RW is less, which has become the primary problem in its application. A simple model was used to simulate the stress-strain characteristic, and compared to experimental results.