Research on the Bending Performance of a Double-Layer Tenon–Mortise Modularized Conductor (TMMC)

The previously reported Tenon–Mortise Modularized Conductor (TMMC) achieved a critical current (Ic) of 13.69 kA under self-field at 77 K, exhibiting low AC losses. To optimize the bending performance, a double-layer sleeve-assembled TMMC was developed. By adjusting the configuration of the tape stacks, the in-plane bending of the superconducting tapes is reduced, and the flow channels for coolant are increased. A three-dimensional finite element model was established to analyze the strain distribution during the bending process. The influence of the bending radius and the friction coefficient on the average and maximum axial strain of the tapes was analyzed. Furthermore, a 2-meter-long prototype TMMC was fabricated for bending experiments, where the Icof the outermost superconducting tapes were measured under different bending radii. The results show that after bending from 400 mm to 300 mm, significant Icdegradation was observed in the measured tapes, with the maximum degradation reaching 14.17%. Simulation results reveal that at 300 mm, the peak axial strain in several tapes exceeds the irreversible strain limit of 0.4%, which is consistent with the experimental observations. Consequently, the critical bending radius of prototype TMMC is identified to be between 400 mm and 300 mm, confirming that inclined stacks are more susceptible to strain-induced degradation.