Mechanical behavior and strain dependence of the critical current of DI-BSCCO tapes

Abstract

In order to clarify the mechanical properties and their influence on the critical current of DI-BSCCO tapes with and without lamination, mechanical tests and critical current measurements were performed, and the corresponding residual strain exerted on the BSCCO component was measured by a neutron diffraction technique. Also the residual strain analysis was calculated using the rule of mixtures. The measured modulus of elasticity, the second slope, and the stress corresponding to the force free strain were self-consistently explained on the basis of this analytical model. The calculated residual strain in the BSCCO component was found to be nearly identical with that determined by neutron diffraction for all DI-BSCCO tapes except for the case of the low strength insert tape. The difference between the strain corresponding to 95% Ic retention and the force free strain was explained by the fracture strain of BSCCO filaments. An approximate expression to evaluate the residual strain in the BSCCO filaments is also presented along with a procedure for estimating the initial temperature T0 at which the residual strain starts to accumulate during cooling after the fabrication heat treatment.