Development and validation of an apparatus for measuring hysteresis loss in YBCO superconducting tapes under combined tensile-torsional loading

Abstract Understanding the hysteresis loss mechanism in YBCO tapes under multiaxial stress is crucial for developing high-temperature superconducting magnets. To address the lack of in-situ testing capability for long YBCO tapes under combined tensile, torsional, and alternating magnetic field loads, an integrated measurement platform was developed. This platform consists of an external magnet providing a highly uniform background field and a custom-built subsystem. The subsystem includes a precision combined tensile-torsion loading device (displacement range: 0–50 mm, accuracy: ±10 μm; angular range: 0 ∘ –1080 ∘ , accuracy: ±0.1 ∘ ) and a data acquisition and processing system. Performance verification tests demonstrated that: the tensile loading unit achieved a positioning accuracy better than ±10 μm, the torsion loading unit achieved a positioning accuracy better than 0.1 ∘ , and the measurement consistency for coil parameters was within 0.01%. Under a 0.01 Hz magnetic field, clear hysteresis loops were successfully obtained from tests on unloaded samples. The measured hysteresis loss agreed well with the results from a vibrating sample magnetometer (VSM), with a discrepancy of less than 1.8%. This work establishes a highly reliable experimental platform for investigating the effects of multiaxial stress on the magnetization characteristics of YBCO tapes.