• 제목/요약/키워드: sliding-type bearing

검색결과 62건 처리시간 0.024초

베이스 운동을 받는 다자유도 능동자기베어링계에서 외란 관측기 기반 슬라이딩모드 제어 (Disturbance Observer Based Sliding Mode Control for Multi-DOF Active Magnetic Bearing System Subject to Base Motion)

  • 강민식
    • 한국소음진동공학회논문집
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    • 제14권11호
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    • pp.1182-1194
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    • 2004
  • This paper addresses the application of an active magnetic bearing (AMB) system to levitate the elevation axis of an electro-optical sight mounted on a moving vehicle. In this type of system, it is desirable to retain the elevation axis in an air-gap between magnetic bearing stators while the vehicle is moving. To eliminate disturbance responses, a disturbance observer based sliding mode control is developed. This control can decouple disturbance observation dynamics from sliding mode dynamics and preserves the robustness of the sliding control. The sliding surfaces are designed in the consideration of scattering of received image. The proposed control is applied to a 2-DOF active magnetic bearing system subject to base motion. Along with experimental results, the feasibility of the proposed technique is illustrated.

LRB와 슬라이딩베어링을 혼용한 면진시스템을 적용한 아파트 건물의 지진 응답 (Seismic Response of Apartment Building with Base Isolation System Consisting of Sliding-type Bearing and Lend Rubber Bearing)

  • 천영수;윤영호;황기태;장극관
    • 콘크리트학회논문집
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    • 제19권4호
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    • pp.507-514
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    • 2007
  • 이 논문은 기존 내진설계와 비교하여 면진설계의 효용성과 경제적 효과에 대한 연구 결과를 정리한 것이며, 면진설계에 있어서는 납봉삽입적층고무베어링 (LRB)만을 사용한 경우와 비교하여 슬라이딩베어링과 LRB를 혼용한 면진시스템의 내진 거동을 함께 제시하였다. 연구 결과, 면진은 구조물에 대하여 지진동으로 인한 효과를 감소시키는데 매우 효과적이며, 층 가속도의 감소로 사용성을 증가시킬 수 있음이 입증되었다. 또한 층 가속도와 밑면 전단력의 감소라는 관점에서 슬라이딩베어링과 LRB를 혼용한 면진시스템이 LRB만을 사용한 경우보다 더 효과적임을 증명하였다. 하지만 경제적 효과 면에서는 증가된 성능에 비례하여 지불해야만 하는 비용도 커진다는 사실에 특별히 주의할 필요가 있는 것으로 나타났다.

반발식 자기 베어링의 응용으로서 고온 초전도체의 특성에 관한 실험적 연구 (An Experimental Study on the Characteristics of the High Temperature Superconductor as an Application of the Repulsive Type Magnetic Bearing)

  • 유제환;임윤철
    • Tribology and Lubricants
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    • 제13권2호
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    • pp.52-59
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    • 1997
  • An experimental study is presented for the characteristics of the high temperature superconductor as an application of the repulsive type magnetic bearing. A ring shaped YBCO type superconductor and Neodium permanent magnets are employed for the experiment. For the case of field cooling, superconductor shows strong repulsive force, which is due to the Meissner effect, as the gap between the superconductor and the magnet gets closer. The repulsive force variation with respect to the gap change shows hysterisis characteristics. The area of the loop of the hysterisis curve represents the dissipation of energy, which reveals that the magnetic bearing with superconductor has large damping. The effect of the initial gap and the magnetic flux density on the repulsive force is analyzed experimentally and the static stiffness variation is calculated from the measured repulsive force variation. The relative sliding velocity between the superconductor and the magnet has little effect on the repulsive force which is quite different from the usual sliding element bearing. As the initial gap for the field cooling becomes larger, the maximum repulsive force at the minimum gap increases and approaches to the value for the case of zero field cooling.

Seismic response analysis of isolated offshore bridge with friction sliding bearings

  • Wang, Baofu;Han, Qiang;Jia, Junfeng
    • Earthquakes and Structures
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    • 제16권6호
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    • pp.641-654
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    • 2019
  • This paper investigates the seismic response of a typical non-navigable continuous girder bridge isolated with friction sliding bearings of the Hong Kong-Zhuhai-Macao link projects in China. The effectiveness of the friction pendulum system (FPS) and accuracy of the numerical model were evaluated by a 1/20 scaled bridge model using shaking table tests. Based on the hysteretic properties of friction pendulum system (FPS), double concave friction pendulum (DCFP), and triple friction pendulum system (TFPS), seismic response analyses of isolated bridges with the three sliding-type bearings are systematically carried out considering soil-pile interaction under offshore soft clay conditions. The fast nonlinear analysis (FNA) method and response spectrum are employed to investigate the seismic response of isolated offshore bridge structures. The numerical results show that the implementation of the three sliding-type bearings effectively reduce the base shear and bending moment of the reinforced concrete pier, at the cost of increasing the absolute displacement of the bridge superstructure. Furthermore, the TFPS and DCFP bearings show better isolation effect than FPS bearing for the example continuous girder bridge.

Numerical Design Method for Water-Lubricated Hybrid Sliding Bearings

  • Feng, Liu;Bin, Lin;Xiaofeng, Zhang
    • International Journal of Precision Engineering and Manufacturing
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    • 제9권1호
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    • pp.47-50
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    • 2008
  • This paper presents a new water-lubricated hybrid sliding bearing for a high speed and high accuracy main shaft system, along with the numerical method used for its design. The porous material for the restrictor and the restriction parameter were chosen based on the special requirements of the water-lubricated bearing. Subsequent numerical calculations give the load capacity, stiffness, and friction power of different forms of water-lubricated bearings. The pressure distribution of the water film in a 6-cavity bearing is shown, based on the results of the numerical calculations. A comparison of oil-lubricated and water-lubricated bearings shows that the latter benefits more from improved processing precision and efficiency. An analysis of the stiffness and friction power results shows that 6-cavity bearings are the preferred type, due their greater stiffness and lower friction power. The average elevated temperature was calculated and found to be satisfactory. The relevant parameters of the porous restrictor were determined by calculating the restriction rate. All these results indicate that this design for a water-lubricated bearing meets specifications for high speed and high accuracy.

패드와 피봇 사이의 마찰이 틸팅패드 저널베어링에 미치는 영향 (Influence of Pad-Pivot Friction on the Performance of Tilting-Pad proceeding Bearing)

  • 김성기;김경웅;하현천
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 추계학술대회
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    • pp.1016-1021
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    • 2004
  • The need for developing a mathematical model for pad-pivot friction in tilting pad proceeding bearings has been well-recognized, since previous experimental work about the performances of the bearings hypothesized that the friction in the bearings is closely related to their performances. Especially, the sliding friction between pad and pivot in the ball and socket type of the bearings can influence the performance of the bearing. We propose a mathematical model for pad-pivot friction in the ball and socket type, which considers the geometrics of the pad and pivot of the bearings, by assuming the sliding friction in the ball and socket bearing as Coulomb friction. By utilizing the proposed model for pad-pivot friction, we show the analysis of Reynolds equation and energy equation, which explain the thermo-hydrodynamic characteristics of tilting pad proceeding bearings, by taking into account the turbulence and inlet pressure building as well. The results of the study show that the performance of titling-pad proceeding bearings can be greatly influenced by the pad-pivot friction. In particular, we have shown that the analysis of the pad-pivot friction is useful to explain the static proceeding loci and the dynamic characteristics of the ball and socket type of the bearings. Furthermore, for a given operating condition, we can obtain various equilibrium states which satisfy the static equilibrium conditions, by considering the pad-pivot friction.

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습도 및 미끄럼 속도에 따른 질화규소의 마찰 마모 특성에 관한 연구 (Effects of Humidity and Sliding Speed on the Wear Properties of $Si_3N_4$ Ceramics)

  • 이기현;김경웅
    • Tribology and Lubricants
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    • 제9권2호
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    • pp.63-69
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    • 1993
  • The wear properties of two types of $Si_3N_4$(silicon nitride) exposed to high and low humidity were examined experimentally for various sliding speed. Bearing steel was used as the disk material at pin-on-disk type sliding. Wear rates of pressureless sintered-plus-hot-isostatic pressed Si3N4 were slightly lower than those of pressureless sintered $Si_3N_4$. It was observed that adsorbed moisture and sliding speed markedly influenced the wear properties of $Si_3N_4$. The highest wear rate was obtained under the high humidity and low sliding speed condition. As the sliding speed was increased, wear rates were decreased and the humidity effect on the wear rates of $Si_3N_4$ was lowered. The result that the $Si_3N_4$ pin showed a high wear rate under the high humidity condition was explained by the property change due to the adsorbed moisture, plowing action by the hard particles of $Fe_2O_3$ from the disk, and the corrosion effect at $Si_3N_4$ surface. Increase in sliding speed was supposed to have reduced the humidity effect on wear rate of $Si_3N_4$ by raising the temperature of both the bearing steel disk and $Si_3N_4$ pin specimen.

유압모터 구면 정압베어링의 마찰특성에 관한 연구 (The study on the friction characteristics of spherical hydrostatic bearing for hydraulic piston motor)

  • 함영복;최영호;김성동
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2001년도 춘계학술대회 논문집
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    • pp.647-650
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    • 2001
  • In case of bent axis type axial piston hydraulic pump or motor, hydrostatic bearing used to achieve the lubrication effect on the mechanical sliding contact areas between the following pairs ; piston shoe and swash plate, valve plate and cylinder block, piston and cylinder block, etc. In this research, we designed two pairs of spherical ball joint in witch connecting rod piston end. The one is not hydrostatic bearing, the other is designed with spherical hydrostatic bearing in point of view minimum pumping power loss. By varying supply pressure on the piston, we can know that it is possible to reduce the friction torque by using hydrostatic bearing designed one. Finally, by comparing the results of driving torque between the two models, it was verified that the spherical hydrostatic bearing is well designed.

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습도 및 미끄럼속도가 질화규소의 마멸거동에 미치는 영향에 관한 연구 (Effects of Humidity and Sliding Speed on the Wear Behavior of Silicon Nitride Ceramics)

  • 이기현;김경웅
    • 대한기계학회논문집
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    • 제18권10호
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    • pp.2597-2605
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    • 1994
  • The wear behavior of two types of $Si_3N_4$ exposed to high and low humidity was examined at various sliding speeds, using bearing steel as disk material under pin-on-disk type sliding conditions. Higher wear rates were obtained at a high humidity than at a low humidity. As the sliding speed was increased, the wear rates were decreased and the effect of humidity on the wear rates of $Si_3N_4$ was reduced. The result that the $Si_3N_4$ pin showed higher wear rate under the high humidity condition was explained by the decrease in microhardness of $Si_3N_4$ due to the chemisorbed moisture on the pin and plowing action by the hard particles of $Fe_2O_3$ from the disk. An increase in the sliding speed is supposed to reduce the effect of humidity on the wear rate of $Si_3N_4$ by raising the average temperature of the disk surface and the local temperature at pin-disk contact point.

미끄럼 스러스트베어링의 성능에 미치는 베어링 형상의 영향 해석 (Analytical Study on Effects of Bearing Geometry on Performance of Sliding Thrust Bearings)

  • 김호종;최성필;하현천
    • 한국유체기계학회 논문집
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    • 제9권5호
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    • pp.7-13
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    • 2006
  • In the present study, we develop an analysis module to be applicable to design of sliding thrust bearings. The pressure equation is solved by using the finite element method. Average lubricant temperature is obtained from using the energy balance method. The module developed has been applied to three types of thrust bearing, such as tapered-land thrust bearings of angular and diamond types, and tilting-pad thrust bearings. Effects of the dam of the tapered-lad thrust bearings have also been investigated. It has been seen that the tapered-land thrust bearings of angular type result in the highest load capacity, while the tilting pad thrust bearings result in the lowest lubricant temperature. It has also been seen that the dam in the tapered-land thrust bearings increases both the load capacity and lubricant temperature.