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Identification of Frequency-Dependent Dynamic Characteristics of a Bump Structure for Gas-Foil Bearings via 1-DOF Shaker Tests Under Air Pressurization

가스 포일 베어링 범프 구조의 1 자유도 가진/가압 실험을 통한 주파수 의존 동특성 규명

  • Sim, Kyuho (Dept. of Mechanical System Design Engineering, Seoul Nat'l Univ. of Sci. & Tech.) ;
  • Park, Jisu (Dept. of Mechanical System Design Engineering, Seoul Nat'l Univ. of Sci. & Tech.) ;
  • Lee, Sanghun (Dept. of Mechanical System Design Engineering, Seoul Nat'l Univ. of Sci. & Tech.)
  • 심규호 (서울과학기술대학교 기계시스템디자인공학과) ;
  • 박지수 (서울과학기술대학교 기계시스템디자인공학과) ;
  • 이상훈 (서울과학기술대학교 기계시스템디자인공학과)
  • Received : 2015.06.11
  • Accepted : 2015.07.12
  • Published : 2015.10.01

Abstract

Recently, the importance of rotordynamic stability has been increased because of the tendency to employ ultra-high speeds in rotating machinery. In particular, the dynamic characteristics of gas bearings for high-speed rotating machinery need to be identified at various excitation frequencies to predict the rotor's behavior. In this study, we perform dynamic loading tests for gas-foil bearings (GFBs) to determine the bump foil structure and an air-film combined bump-foil structure for varying excitation frequencies. We calculate the dynamic characteristics from the measured force and displacement data. The air film is generated by a pressurized air supply. Based on the results, the stiffness coefficients of the bump structure and the air-film combined bump structure increased, while the damping coefficients decreased at increasing excitation frequencies. Further, the stiffness and damping coefficients of the air-film combined structure show lower values than those of the bump structure. Consequently, we identify the frequency-dependent dynamic characteristics of the bump structure and the effect of gas film on the dynamic characteristics of GFBs. Furthermore, to reveal the effectiveness of the proposed method, we perform experiments and discuss two methods of extracting the dynamic characteristics from the measured data.

Keywords

Gas Foil Bearing;Dynamic Characteristics;Hysteresis loop

Acknowledgement

Supported by : 한국연구재단

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