Vibration of the Vertical Rigid Rotor Supported by a Repulsive-Type Magnetic Bearing: Effects of Both the Axial Displacement and the Magnetical Anisotropicities of Magnets

2007 ◽  
Author(s):  
Tsuyoshi Inoue ◽  
Yukio Ishida ◽  
Tomohiro Sugai
Keyword(s):  
Permanent Magnet ◽  
Magnetic Bearing ◽  
Axial Displacement ◽  
Rigid Rotor ◽  
Rotating Shaft ◽  
Restoring Force ◽  
Uniform Magnetization ◽  
Nonlinear Force ◽  
Linear And Nonlinear ◽  
Force Characteristics

Magnetic bearing is considered for the usage in various industries. This paper investigates vibration of the rotating shaft supported passively by a repulsive-type magnetic bearing. The permanent magnet on the market not only has strong nonlinear force characteristics, but also may have a few percents of non-uniform magnetization characteristics. Also nonlinear force characteristics change as axial displacement of the shaft. Restoring force of a repulsive-type magnetic bearing is evaluated numerically considering the effects of both the axial displacement of the shaft and the magnetical anisotropicities of the inner and outer magnets. The occurrences of not only the linear and nonlinear parametric characteristics, but also the excitational forces for each pattern of magnetical anisotropicities are observed and they are evaluated in terms of the axial displacement. Furthermore, the influence of each magnetical anisotropicity pattern on the occurrences of various resonance phenomena is clarified.

Vibration of the Rigid Rotor Supported by a Repulsive Magnetic Bearing (Influences of Magnetic Anisotropies of Magnets)

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Tsuyoshi Inoue ◽  
Yukio Ishida ◽  
Takeshi Tsumura
Keyword(s):  
Magnetic Anisotropy ◽  
Magnetic Bearing ◽  
Rigid Rotor ◽  
Restoring Force ◽  
Resonance Phenomena ◽  
Linear And Nonlinear

This study focuses on the vibration of the rotor supported by a repulsive-type passive magnetic bearing. It evaluates the restoring force of a repulsive magnetic bearing numerically by considering the effects of magnetic anisotropies of the inner and the outer magnets. The study mainly investigates the occurrences of linear and nonlinear parametric characteristics, and the excitation forces for each pattern of magnetic anisotropies. Moreover, it clarifies the effects of each magnetic anisotropy pattern on the occurrences of various resonance phenomena theoretically and experimentally.

Contact Whirling Vibration of a Rotating Shaft Supported by a Repulsive Magnetic Bearing and the Influence of the Axial Displacement on Its Suppression

2011 ◽  
Author(s):  
Tomohiro Sugai ◽  
Tsuyoshi Inoue ◽  
Yukio Ishida
Keyword(s):  
Rotational Speed ◽  
Critical Speed ◽  
Nonlinear Coefficient ◽  
Magnetic Bearing ◽  
Axial Displacement ◽  
Damping Coefficient ◽  
Rotating Shaft ◽  
Escape Speed

A rotating shaft supported by a repulsive magnetic bearing may contact with a backup bearing during the passage of the critical speed as the damping coefficient of the repulsive magnetic bearing is small. This paper investigates the contact vibration during passage of the critical speed. Particularly, the influence of the axial displacement of the repulsive magnetic bearing on the escape speed from the contact vibration is focused. As a result, it is clarified that the rotational speed of the escapement from the contact vibration decreases as the axial displacement increases. It is explained by the change of both the linear stiffness and nonlinear coefficient in the increase of the axial displacement.

scholarly journals Seismic Strengthening Effects of Full-Size Reinforced Concrete Frame Retrofitted with Novel Concrete-Filled Tube Modular Frame by Pseudo-Dynamic Testing

2021 ◽  
Vol 11 (11) ◽  
pp. 4898
Author(s):  
Jin-Seon Kim ◽  
Ju-Seong Jung ◽  
Dong-Keun Jung ◽  
Eui-Yong Kim ◽  
Kang-Seok Lee
Keyword(s):  
Dynamic Analysis ◽  
Shear Failure ◽  
Dynamic Testing ◽  
Seismic Intensity ◽  
Seismic Retrofitting ◽  
Restoring Force ◽  
Rc Structures ◽  
Linear Dynamic ◽  
Non Linear ◽  
Force Characteristics

The present study proposes a new seismic retrofitting method using a concrete-filled tube modular frame (CFT-MF) system, a novel technique to overcome and improve the limitations of existing seismic strengthening methods. This CFT-MF seismic retrofitting method makes the most of the advantages of both concrete and steel pipes, thereby significantly improving constructability and increasing integration between the existing structure and the reinforcement joints. This method falls into the category of typical seismic retrofitting methods that focus on increasing strength, in which the required amount of seismic reinforcement can be easily estimated. Therefore, the method provides an easy solution to improving the strength of existing reinforced concrete (RC) structures with non-seismic details that are prone to shear failure. In the present study, a full-size two-story test frame modeled from existing domestic RC structures with non-seismic details was subjected to pseudo-dynamic testing. As a result, the effect of the CFT-MF system, when applied to existing RC structures, was examined and verified, especially as to its seismic retrofitting performance, i.e., restoring force characteristics, stiffness reinforcement, and seismic response control. In addition, based on the pseudo-dynamic testing results, a restoring force characteristics model was proposed to implement non-linear dynamic analysis of a structure retrofitted with the CFT-MF system (i.e., the test frame). Finally, based on the proposed restoring force characteristics, non-linear dynamic analysis was conducted, and the results were compared with those obtained by the pseudo-dynamic tests. The results showed that the RC frame (building) with no retrofitting measures applied underwent shear failure at a seismic intensity of 200 cm/s2, the threshold applied in seismic design in Korea. In contrast, in the frame (building) retrofitted with the CFT-MF system, only minor earthquake damage was observed, and even when the maximum seismic intensity (300 cm/s2) that may occur in Korean was applied, small-scale damage was observed. These results confirmed the validity of the seismic retrofitting method based on the CFT-MF system developed in the present study. The non-linear dynamic analysis and the pseudo-dynamic test showed similar results, with an average deviation of 10% or less in seismic response load and displacement.

Sign in / Sign up

Export Citation Format

Share Document