Combination Resonance of a Rotor Supported by a High-Tc Superconducting Bearing

Toshihiko Sugiura, Keniti Matsunaga, Takuo Kugiya, Masatsugu Yoshizawa

Research output: Contribution to journalArticlepeer-review


This research deals with nonlinear dynamics of a rotating rigid magnet levitated above a high Tc superconducting (HTSC) bulk. Motion of the rotating magnet in the radial and axial directions were investigated theoretically by using analytical expression of electromagnetic force obtained by “the advanced mirror image method”. Analytical and numerical results show existence of combination resonance due to nonlinear coupling between whirling and vertical motion of the magnet. The resonant frequency of rotation is given as the sum of the natural frequency in the horizontal and vertical directions. At this resonance, the whirling motion becomes quasi-periodic, having the harmonics with both the driving and natural frequencies, while periodic motion at the natural frequency appears in the vertical direction. Stability analysis shows that this resonance occurs if the eccentricity of the magnet is larger than a certain critical value. Experiments for spinning motion of the magnet were carried out, and combination resonance predicted in the theory was clearly observed. Nonlinearity in forces can thus have significant effects on dynamics in application of HTSC bearings.

Original languageEnglish
Pages (from-to)3568-3575
Number of pages8
JournalNihon Kikai Gakkai Ronbunshu, C Hen/Transactions of the Japan Society of Mechanical Engineers, Part C
Issue number651
Publication statusPublished - 2000


  • Combination Resonance
  • Coupled Vibration
  • Electromagnetic Force
  • High-Tc Superconducting Bearing
  • Nonlinear Vibration
  • Vibration of Rotating Body

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Industrial and Manufacturing Engineering


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