• Title/Summary/Keyword: Coupled by Bearing

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Design and Analysis of Permanent Magnet Synchronous Generator Considering Magnetically Coupled Turbine-Rotor System

  • Kim, Byung-Ok;Choi, Bum-Seog;Kim, Jeong-Man;Cho, Han-Wook
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.1002-1006
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    • 2015
  • In this paper, design and analysis of permanent magnet synchronous generator for ocean thermal energy conversion (OTEC) considering magnetically coupled turbine-rotor system is discussed. In particular, the rotor dynamics considering bearing span and journal shaft diameter is highlighted. The two topologies of permanent magnet synchronous generator with magnetic coupling are employed for comparison of computed rotor dynamics and generating characteristics. The analysis results show that the critical speed of the turbine-rotor system is higher when the rotor is coupled by magnetically coupling. Finally, the experimental results confirmed the validity of the proposed design and analysis scheme and successful development.

Dynamic Analysis Program for Disk Drive Spindle Systems (디스크 드라이브 스핀들 계의 동특성 해석 프로그램)

  • 오동호;김철순;박노열;노광춘
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.211-217
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    • 1998
  • A disk rotor dynamic analysis program called by DR. DAP is developed for disk drive spindle systems to analyze dynamic characteristics in operation and to estimate the effects of excitation sources. It is applicable to design for stabilization and to select parts of disk drive spindle systems. The disk drive spindle system in this program is modeled as a flexible shaft with multiple flexible disks, which is supported by bearings and driven by electric motor, and its complicated coupled vibration characteristics are analyzed by using a substructure synthesis technique with the assumed-modes method. All the coupled modes of interest can be well predicted by the example of a three disk hard disk drive with the three tuning parameters. It is also shown that, with the introduction of the excitation sources associated with the defects of ball bearing systems, the magnetic unbalance of spindle motor, the program can well predict the stability of the system, i.e., the possibility of resonance.

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Seismic Responses Control of Coupled Shear Wall Structures Using LRBs (LRB를 이용한 병렬전단벽 구조물의 지진응답제어)

  • Park, Yong-Koo;Kim, Hyun-Su;Ko, Hyun;Kim, Min-Gyun;Lee, Dong-Guen
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.6
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    • pp.1-9
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    • 2010
  • Most of shear wall structures require openings in shear walls and thus shear walls are linked by floor slabs or coupling beams resulting in the coupled shear wall structures. When these structures are subjected to seismic excitations, excessive shear forces are induced in coupling beams. Accordingly, brittle failure of coupling beams may occur or shear walls may yield first. To avoid this problem, damping devices can be installed in coupling beams. It can increase the vibration control effect and improve the seismic resistance performance of the coupled shear wall structure by avoiding stress concentration and the brittle failure of coupling beams. Based on this background research, an LRB (lead rubber bearing) was introduced in the middle of the coupling beam in this study and the authors investigated the seismic response control effect and stress distribution of the proposed system. To this end, a modeling technique that can effectively predict the structural behavior of coupled shear wall structures has been proposed. With this proposed technique, time history analyses of the example coupled shear wall structure subjected to seismic excitation were performed and the vibration control effects of the seismic responses were investigated.

An Experimental Study on the Damping Capacity of Lead Rubber Bearing with High Lead-plug Area Ratio (납-플러그 면적비가 큰 LRB의 감쇠능력에 관한 실험적 연구)

  • Choi, Jung-Ho;Kim, Woon-Hak
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.3 s.55
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    • pp.217-224
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    • 2009
  • Many engineering researches are performed to ensuring structural safety from earthquake. In this study, the damping capacity of LRB(lead rubber bearing) with high lead-plug area ratio was examined by hysteresis loop from experiments. The displacement controlled tests were performed for 12 specimens designed in 2 types by lead-plug area ratio as main parameter. Each coupled specimens were tested by 3 times sinusoidal loads with different loading velocities. From the experimental results, LRB with high lead-plug area ratio has sufficient damping ratio for reducing horizontal seismic load to structures.

The Influence of Surface Roughness on Thermohydrodynamic Analysis (열유체 윤활해석에 의한 표면 거칠기가 마찰거동에 미치는 영향 고찰)

  • Kim, Joon-Hyun;Kim, Seong-Keol;Kim, Joo-Hyun
    • Proceedings of the KSME Conference
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    • 2001.06c
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    • pp.299-304
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    • 2001
  • An approach is developed for parametric investigation of the influence of the surface roughness on thermohydrodynamic analysis with film conditions which systemically occur in journal bearings. A parametric investigation is performed for predicting the bearing behaviors such as pressure and temperature distributions in lubricating films between the stationary and moving surfaces determined by absorbed layers and interfaces on the statistical method for rough surface with Gaussian distribution. The layers expressing the effects of surface roughness are expressed as functions of the standard deviations (${\sigma}$) of each surface and surface orientation (j) to explain the flow patterns between both rough surfaces. The coupled effect of surface roughness and shear zone dependency on hydrodynamic pressure and temperature has been found by solving the present model in non-contact mode and contact mode, respectively.

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Behavior and Failure Mode of Steel Coupling Beams Joint with FBP (FBP가 설치된 철골 커플링보 접합부의 거동 및 파괴모드)

  • Song Han-Beom;Yi Waon-Ho
    • Journal of the Korea Concrete Institute
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    • v.17 no.6 s.90
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    • pp.1001-1009
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    • 2005
  • The usefulness of walls in the structural planning of multistory buildings has long been recognized. When walls are situated in advantageous positions in a buildings, they can be very efficient in resisting lateral load. Specially coupled shear wall system is the primary lateral load resisting system of buildings. It is customary to refer to such walls as being 'coupled' by coupling beams. The coupling beams must exhibit excellent strength, stiffness ductility and energy dissipation capacity. To achieve these demands for steel coupling beam, steel coupling beam with Face Bearing Plate(FBP) embedded in the reinforced concrete walls is proposed. A comprehensive experimental test involving 2 steel coupling beam with and without FBP has been performed. Through experimental study, the evaluation of the advantage of that was establish and proposed the failure mode.

Thermohydrodynamic Analysis Considering Flow Field Patterns Between Roughness Surfaces (미세 표면 거칠기에 지배되는 박막 유동장 형태를 고려한 윤활거동)

  • 김준현;김주현
    • Tribology and Lubricants
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    • v.19 no.3
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    • pp.167-177
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    • 2003
  • The study deals with the development of a thermohydrodynamic (THD) computational procedure for evaluating the pressure, temperature and velocity distributions in fluid films with very rough geometry. A parametric investigation is performed to predict the bearing behaviors in the lubricating film having the absorbed layers and their interfaces determined by the rough surfaces with Gaussian distribution. The layers are expressed as functions of the standard deviations of each surface to characterize flow patterns between both the rough sur-faces. The velocity variations and the heat generation are assumed to occur in the central (shear) zone with the same bearing length and width. The coupled effect of surface roughness and shear zone dependency on hydrodynamic pressure and temperature has been found in non-contact mode. The procedure confirms the numerically determined relationship between the pressure and film gap on condition that its roughness magnitude is smaller than the fluid film thickness.

A Study of Thermal Effects for a Half-Circumferential Grooved Journal Bearing (半圓周形 윤활홈을 갖는 저어널 베어링의 熱效果에 관한 연구)

  • Chun, Sang-Myung;Lalas, Demetrius P.
    • Tribology and Lubricants
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    • v.6 no.1
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    • pp.36-51
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    • 1990
  • A parametric study of the thermal effects of a half-circumferential grooved journal bearings under aligned and misaligned conditions has been carried out by solving numerically the coupled Reynolds and energy equation system. Five different sets of boundary conditions for the energy equation have been used which include mixing between recirculating oil and inlet oil and a contraction ratio for the cavitation region. The effects of changes of the inlet oil temperature and pressure, the wall temperature and the L/D ratio have also been examined. For the range of parameters found in internal combustion engines, the mixing effectiveness at the groove and the resulting final mixture temperature have been found to be as important as the wall temperature and the heat transfer rate. The variability of the temperature, though, has been shown to smooth out the peaks of both pressure and friction during misaligned condition Distributions of friction and pressure in the oil are also examined which may be useful in attempts to reduce friction without reducing load. Results for an axial grooved bearing are also presentsed for comparision purpose.

Rotordynamic Performance of High-Tc superconductor Bearings (고온초전도베어링의 회전체역학적 특성)

  • 성태현;이준성;한영희;김영철;최상규;김상준
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2000.02a
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    • pp.180-184
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    • 2000
  • The dymanic properties of the high-Tc superconductor journal bearings used in the KEPRI flywheel energy storage system was experimentally estimated by using the imbalance excitation method. The test reveals that the superconductor bearings have very low stiffness compared to that of typical oil film bearings with similar geometry and almost the same amount of damping as in roller bearings, which may not be helpful for the system to pass through the critical speeds. However, it was found out that the cross-coupled stiffness and damping terms were almost negligible so that the system could be more stable than the one using lil film bearings. Also with proper design of the rotor-bearing system and accurate balancing of the rotor, the high-Tc superconductor bearing is one of the most viable alternatives to the conventional ones due to its oil-free, non-contact running capability in a vacuum environment, which is literally essential for highly efficient flywheel energy storage systems.

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Coupled Vibration Analysis and Sensitivity of HDD using the Finite Element Method (유한요소법을 이용한 하드디스크의 회전 연성 진동 해석 및 설계민감도 연구)

  • Wang, Se-Myung;Yi, Ki-Young
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.472-478
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    • 2000
  • The vibration of the hard disk drive (HDD) systems, which comprises flexible disks, flexible shafts, bearings, and base structures, are analyzed by a finite element method (FEM) to cope with complicated coupling effects between them. The natural frequencies and mode shapes of the uncoupled, axial and bending coupled vibrations are calculated. Modal testing of the HDD systems is performed to validate the finite element analysis (FEA) results. Good agreement was obtained between the computed and experimental results. Sizing design sensitivity analysis (DSA) of the system was performed with the thickness of base structure and bearing stiffness as design variables. The DSA results tell how can I increase or decrease eigenvalue of the system effectively.

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