The present document reports the results of experimental measurements and numerical studies of strains and stresses arising in second generation Rare-earth Barium Copper Oxide Coated Conductors (2G REBCO CC), which are close to be used in electrical network devices such as Superconducting Fault Current Limiters (SFCL) and superconducting cables. These tapes are multilayer systems composed of materials with different physical and mechanical properties.

When subjected to cryogenic temperatures in test and operating configurations, they experience thermo-mechanical stresses that, if above certain threshold values, can cause irreversible degradation of electrical and mechanical performance, making them unusable.

The results of the study of the thermoelastic behavior of superconductor tapes are here reported. This study was carried out experimentally, by strain gage techniques, and theoretically, through numerical simulations. Experimental measurements were accomplished on tape samples in linear and cylindrical configurations. In both cases the resulting stresses are below their safety limits.

The Coefficients of Thermal Expansion of the examined tapes and of the materials constituting the constraint, at cryogenic temperatures were measured as well by strain gages. Understanding the thermal expansion coefficients will clarify how the materials of the tape-constraint system interact with each other. This will enable to select the constraint materials to minimize stresses at critical points of the tape.

Numerical simulations of the thermoelastic behavior of the tape were performed, considering its multilayer structure, by using the COMSOL Multiphysics software. Various average stresses on superconductor tapes were worked out. Moreover, appropriate boundary conditions for the simulations were chosen and applied. The average stresses turned out to be comparable to those calculated from experimental strain measurements. Studies on boundary conditions, geometry and physical hypotheses can be further extended.

The experiments and numerical simulations conducted here have contributed to increase the knowledge on the subject not yet available, to the best of the authors’ knowledge, in the scientific literature.

The Report is available on the Italian site