Dynamic Analysis and Validation of Superconducting Rotor With a Spoke Suspension Torque Tube

A superconducting rotor with a spoke suspension system can achieve a high specific power of 40 kW/kg. The spokes act as a torque tube with strong thermal insulation, virtually eliminating the conductive heat transfer between the ambient-temperature drive shaft and the cryogenic rotor shell, where superconducting coils are mounted. However, since the spoke geometries differ from a solid torque tube, existing rotordynamic analytical models are not directly applicable. This paper presents an analytical model for the dynamic behavior of the spoke system, validated through finite element (FE) analysis and experimental impact testing. The study is conducted through three aspects: analytical derivation of the spoke system resonant frequencies, 3-D finite element modal verification using Comsol, and experimental validation through a ping test. The first six mode shapes and modal frequencies show minimal discrepancies among these methods. The calibrated FE model is then used to generate a Campbell diagram for rotordynamic analysis. This study provides a useful calibrated tool for predicting the dynamic behavior of the suspension system.