• Title/Summary/Keyword: Rotor Unbalance

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Vibration Optimization Using Immune-GA Algorithm (면역-유전알고리즘을 이용한 진동최적화)

  • 최병근;양보석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.273-279
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    • 1998
  • An immune system has powerful abilities such as memory, recognition and learning to respond to invading antigens, and is applied to many engineering algorithm recently. In this paper, the combined optimization algorithm is proposed for multi-optimization problem by introducing the capability of the immune system that controls the proliferation of clones to the genetic algorithm. The optimizing ability of the proposed optimization algorithm is identified by using two multi-peak functions which have many local optimums and optimization of the unbalance response function for rotor model.

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A Study on the Characteristics of Sound Source of Hydrodynamic proceeding Bearings (유체 윤활 저널베어링의 음원 특성에 관한 연구)

  • Rho, Byoung-Hoo;Kim, Kyung-Woong
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.05a
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    • pp.156-161
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    • 2002
  • Results of theoretical investigations on acoustical properties of hydrodynamic proceeding bearings are presented. Nonlinear analysis of rotor bearing system including rotor imbalance is performed in order to obtain acoustical properties of hydrodynamic proceeding bearings. Furthermore, a cavitation algorithm, implementing the Jakobsson-Floberg-Olsson boundary condition, is adopted to predict cavitation regions in a fluid film. Acoustical properties of hydrodynamic proceeding bearings are identified through frequency analysis of pressure fluctuation calculated from the nonlinear transient analysis. The results show that the acoustical frequency spectra of hydrodynamic proceeding bearings are pure tone spectra, containing the frequency of the shaft rotation and its super-harmonics. The analysis also shows that the super-harmonics are predominant at neighborhood of the fluid film reformation and rupture regions.

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The Effect of Oil Supply Pressure on the Performance of Vapor Cavitated Short Squeeze Film Dampers (증기 공동현상이 발생하는 무한 소폭 스퀴즈 필름 댐퍼 성능과 오일 공급압력의 영향)

  • Jung, Si-Young
    • Tribology and Lubricants
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    • v.24 no.3
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    • pp.147-153
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    • 2008
  • The effect of oil supply pressure on the performance of vapor cavitated short squeeze film dampers is examined. Vapor cavitation is characterized by film rupture occurring as a result of evaporating oils. The pressure of vapor cavity in the film is almost zero in absolute pressure and nearly constant. Pan's model about the shape of vapor cavity is utilized for studying the effect of vapor cavitation on the damping capability of a short squeeze film damper. As the level of oil supply pressure is increasing, vapor cavitation is suppressed so that the direct damping coefficient increases and the cross coupled damping coefficient decreases. Futhermore, the analysis of the unbalance responses of a rigid rotor supported on cavitated squeeze film dampers shows that a significant reduction in rotor amplitude and force transmissibility is possible by controlling the oil supply pressure into short squeeze film dampers.

Analysis of Perturbation Effect for Satellites (인공위성의 섭동력 영향분석)

  • 박수홍
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.229-232
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    • 1997
  • In this paper, the case study of reducing rotational errors is done for a grinding spindle with an active magnetic bearing system. The rotational errors acting on the magnetic bearing spindle are due to mass unbalance of rotor, runout, grinding excitation and unmodeled nonlinear dynamics of electromagnets. For the most case, the electrical runout of sensor target is big even in well-finished surface; this runout can cause a rotation error amplified by feedback control system. The adaptive feedforward method based on LMS algorithm is discussed to compensate this kind of runout effects, and investigated its effectiveness by numerical simulation and experimental analysis. The rotor orbit size in both bearings is reduced about to 5 pin due to lX rejection by feedforward control up to 50,000 rpm.

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Adaptive Runout Control of Magnetically Suspended High Speed Grinder Spindle (자기베어링지지 연삭기 추축계의 고속 회전시 런아웃 적응제어)

  • 노승국;경진호;박종권;최언돈
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.52-55
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    • 1997
  • In this paper, the case study of reducing rotational errors is done for a grinding spindle with an active magnetic bearing system. The rotational errors acting on the magnetic bearing spindle are due to mass unbalance of rotor, runout, grinding excitation and unmodeled nonlinear dynamics of electromagnets. For the most case, the electrical runout of sensor target is big even in well-finished surface; this runout can cause a rotation error amplified by feedback control system. The adaptive feedforward method based on LMS algorithm is discussed to compensate this kind of runout effects, and investigated its effectiveness by numerical simulation and experimental analysis. The rotor orbit size in both bearings is reduced about to 5 pin due to lX rejection by feedforward control up to 50, 000 rpm.

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Analysis and Design of Diaphragm-type Air Braking System for Train (철도차량의 막판식 공기제동시스템의 해석 및 설계)

  • 노진환;김재도
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.605-608
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    • 1997
  • In this paper, the case study of reducing rotational errors is done for a grinding spindle with an active magnetic bearing system. The rotational errors acting on the magnetic bearing spindle are due to mass unbalance of rotor, runout, grinding excitation and ed nonlinear dynamics of electromagnets. For the most case, the electrical runout of sensor target is big even in well-finished surface; this runout can cause a rotation error amplified by feedback control system. The adaptive feedforward method based on LMS algorithm is discussed to compensate this kind of runout effects, and investigated its effectiveness by numerical simulation and experimental analysis. The rotor orbit size in both bearings is reduced about to 5 pin due to lX rejection by feedforward control up to 50,000 rpm.

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The evaluation of vibration contribution about the eccentric rotor system by multiple dimensional spectral analysis (다차원 해석법을 이용한 편심 회전체의 전달 기여도 평가)

  • 조문갑;조용구;김동원;이정윤;오재응
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.298-303
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    • 2003
  • The eccentric rotor system has various problems by vibration of unbalance mass. Specially, it is difficult to analyze vibration problem for the drum washing machine due to correlation of transmission paths. We analyze the mechanical structure by multidimensional spectral density to identify the maximum vibration magnitude at the frequency domain. It estimates the coherence function of the signals to pass the transmission paths. In case of the drum washing machine, because the transmission paths are correlated partially it needs to determinate the priority ranking. And the correlated parts are eliminated using conditioned spectral density function. Finally the shielding effect method confirms the reasonability of the modeling.

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Analysis on the Dynamic Response of Vertical Pumps Subjected to Arbitrary Foundation Excitation (임의 기초여진에 의한 입형 펌프의 동적 응답해석)

  • 여운동
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.26 no.1
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    • pp.57-64
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    • 1990
  • It is important in design of vertical pumps to consider arbitrary foundation excitation in addition to rotor vibration due to unbalance. In this study, a model of a vertical pump was developed for the analysis of its dynamic response. The vertical pump was modeled with lumped masses and springs which represent mult-cylinderical and rotor structure. A dynamic simulation program was developed and numerical calculation on the above mentioned problems were carried out.

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Some case studies of hydrodynamic bearings in power plants in Japan

  • M Tanaka
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2003.11a
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    • pp.1-11
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    • 2003
  • The service reliability of power plants strongly depends on the excellent performance and integrity of hydrodynamic bearings. Consequently, the bearings must be properly designed so as to control vibration amplitudes of rotor due to mass unbalance in passing critical speeds and also suppress self-excited vibrations of rotor even over maximum rated speeds. Furthermore, the bearings must be designed so as to maintain required tribological performance even under severe operating conditions. However, various tribological troubles have been experienced in power plants in Japan. The actual troubles are analysed, focusing on not only direct mechanical causes but also specific bearing designs that surfaced the troubles. Furthermore human factors that decided such designs are also studied. The powerful database of troubles and analyses will contribute greatly to designing advanced power plants with enhanced service reliability in the future. To this end, trouble information should be disclosed, shared and transferred limitlessly. Cooperation of users of power plants is essential to making more advanced design specifications, because no one has easier access to operating and trouble information of power plants than users.

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A Study on the Characteristics of Sound Source of Hydrodynamic Journal Bearings (유체 윤활 저널 베어링의 음원 특성에 관한 연구)

  • Rho, Byoung-Hoo;Kim, Kyung-Woong
    • Tribology and Lubricants
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    • v.18 no.5
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    • pp.333-338
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    • 2002
  • Results of theoretical investigations on acoustical properties of hydrodynamic journal bearings are presented. Nonlinear analysis including rotor imbalance is performed for a rotor-bearing system in order to obtain acoustical properties of hydrodynamic journal bearings. Furthermore, a cavitation algorithm, implementing the Jakobsson-Floberg-Olsson boundary condition, is adopted to predict cavitation regions in a fluid film. Acoustical properties of hydrodynamic journal bearings are identified through frequency analysis of oil pressure fluctuation calculated from the nonlinear transient analysis. The results show that the acoustical frequency spectra of the fluid film are pure tone spectra, containing the frequency of the shaft rotation and its super-harmonics. The analysis also shows that super-harmonics are predominant at the neighborhood of the fluid film reformation and rupture regions.