• Title/Summary/Keyword: fluid force

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Performance Evaluation on an MR Damper Featuring Bypass Hole for Passenger Vehicle (바이패스홀을 특징으로 하는 승용차용 MR 댐퍼의 성능 평가)

  • Oh, Jong-Seok;Shin, Do-Kyun;Sohn, Jung-Woo;Choi, Seung-Bok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.998-999
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    • 2014
  • This paper proposes a method for damping force modeling of magnetorheological (MR) damper featuring bypass hole. After describing configuration and of the MR damper, a damping force modeling of the MR damper is derived based on Bingham model of MR fluid. MR damper consists of piston, accumulator, gap, bypass hole and coil. Damping force is consists of spring force induced by accumulator, viscous force induced at gap and bypass hole, and controllable force induced at gap.

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Influence of a Moving Mass on Dynamic Behavior of a Simply Supported Pipe Conveying Fluid (단순지지 송수관의 동특성에 미치는 이동질량의 영향)

  • 윤한익
    • Journal of Ocean Engineering and Technology
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    • v.15 no.2
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    • pp.135-140
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    • 2001
  • A simply supported pipe conveying fluid and a moving mass upon it constitute a vibrational system. The equation of motion is derived by using Lagrange's equation. The influence of the velocity and the inertia force of a moving mass and the velocities of fluid flow in the pipe have been studied on the dynamic behavior of a simply supported pipe by numerical method. The velocities of fluid low are considered within its critical values of the simply supported pipe without a moving mass upon it. Their coupling effects on the transverse vibration of a simply supported pipe are inspected too. as the velocity of a moving mass increases, the deflection of midspan of a simply supported pipe conveying fluid is increased and the frequency of transverse vibration of the pipe is not varied. Increasing of the velocity of fluid flow makes the frequency of transverse vibration of the simply supported pipe conveying fluid decrease and the deflection of midspan of the pipe increase. The deflection of the simply supported pipe conveying fluid is increased by a coupling of the moving mass and the velocities of a moving mass and fluid flow.

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Neuro-Control of Seismically Excited Structures using Semi-active MR Fluid Damper (반능동 MR 유체 감쇠기를 이용한 지진하중을 받는 구조물의 신경망제어)

  • 이헌재;정형조;오주원;이인원
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.10a
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    • pp.313-320
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    • 2002
  • A new semi-active control strategy for seismic response reduction using a neuro-controller and a magnetorheological (MR) fluid damper is proposed. The proposed control system consists of the improved neuro-controller and the bang-bang-type controller. The improved neuro-controller, which was developed by employing the training algorithm based on a cost function and the sensitivity evaluation algorithm replacing an emulator neural network, produces the desired active control force, and then the bang-bang-type controller causes the MR fluid damper to generate the desired control force, so long as this force is dissipative. In numerical simulation, a three-story building structure is semi-actively controlled by the trained neural network under the historical earthquake records. The simulation results show that the proposed semi-active neuro-control algorithm is quite effective to reduce seismic responses. In addition, the semi-active control system using MR fluid dampers has many attractive features, such as the bounded-input, bounded-output stability and small energy requirements. The results of this investigation, therefore, indicate that the proposed semi-active neuro-control strategy using MR fluid dampers could be effectively used for control of seismically excited structures.

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Durability of Phosphorated Starch Based Electrorheological Fluids in Damper Application (인산화 전분 ER 유체의 댐퍼 내구 특성)

  • Lee, Chul-Hee;Jang, Min-Gyu;Sohn, Jung-Woo;Han, Young-Min;Choi, Seung-Bok
    • Tribology and Lubricants
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    • v.25 no.5
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    • pp.285-291
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    • 2009
  • In this work, durability characteristics of electrorheological (ER) fluid for damper application are experimentally investigated. ER fluid is prepared by using phosphorated starch particles and silicone oil. The field-dependent Bingham characteristics and response time for the proposed ER fluids are experimentally obtained. Experimental apparatus of durability test for ER fluid is established with cylindrical ER cylinder for mid-sized passenger vehicle. In order to evaluate the durability characteristics of ER fluid as a function of time, damping force and temperature variations are measured until one million cycles. After durability test, Bingham characteristics and response time of ER fluid are measured and compared to the initial properties. Microscopic pictures of ER fluid are taken to validate the changes of properties. The results indicate that the ER fluid can be commercially utilized in vehicle damper system with its durability performance. Moreover, the understanding of durability characteristics is essential to predict the service life of ER fluid as well as to design its applications.

Static Characteristic Analysis of Mechanical Face Seal Used for Boiler Feedwater Pump (보일러 급수 펌프용 미케니컬 페이스 실의 정특성 해석)

  • Kim, Dong-Wook;Jin, Sung-Sik;Kim, Jun-Ho;Kim, Kyung-Woong
    • Tribology and Lubricants
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    • v.26 no.4
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    • pp.230-239
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    • 2010
  • Mechanical face seal installed in boiler feedwater pump prevents leakage of working fluid using thin fluid film between stator and rotor. If the leakage of working fluid exceeds the allowable volume, serious malfunction of boiler feedwater pump will be happen. The thinner fluid film exists between stator and rotor, the less working fluid leaks out. However, if the thickness of fluid film is not enough, the wear of seal face will be increased. And it causes the decrease in life of mechanical face seal. Therefore appropriate design is necessary to maximize the performance and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to investigate the static characteristics of wavy mechanical face seals which have 4 different wavy surface profiles on rotor. As a result, opening force, leakage volume of working fluid and friction torque were obtained. For the same minimum film thickness, the static characteristics of mechanical face seal were affected by the wavy surface profile which can change the thickness of working fluid film and pressure distribution.

Dynamic Behavior of a Simply Supported Fluid Flow Pipe with Moving Masses (이동질량들을 가진 단순지지된 유체유동 파이프의 동특성)

  • 윤한익;임순홍
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.2
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    • pp.132-140
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    • 2002
  • A simply supported pipe conveying fluid and the moving masses upon it constitute this vibrational system. The equation of motion is derived by using Lagrange's equation. The influence of the velocity and the inertia force of the moving masses and the velocities of fluid flow in the pipe have been studied on the dynamic behavior of a simply supported pipw by numerical method. The velocities of fluid flow are considered within its critical values of the simply supported pipe without the moving masses upon it. Their coupling effects on the transverse vibration of a simply supported pipe are inspected too. The dynamic deflection of the simply supported pipe conveying fluid is increased by a coupling of the moving masses and the velocities of the moving masses and the fluid flow. When four or five regular interval masses move on the simply supported pipe conveying fluid, the amplitude of the simply supported pipe conveying fluid is small at low velocity of the masses, but at high velocity of the masses the deflection of midspan of the pipe is increased by coupling with the numbers and magnitude of the masses. The time which produce the maximum dynamic deflection of the simply supported pipe is delayed according to the increment of the number of moving masses.

An experimental study on resonance reduction of system with one degree of freedom by magneticfluid (자성 유체를 이용한 1자유도 계의 공진멸소에 관한 실험적 연구)

  • Chun, U. H.;Lee, B. G.;Hwang, S. S.;Lee, H. S.;Kim, J.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.9
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    • pp.131-137
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    • 1999
  • Under magnetism , as the magneticfluid is being itself magnetized, increase the apparent viscosity because of its body force and has the magnetic characteristics in response ot magnetism, the magnetic fluid is getting attention in various field. The magnetic fluid has the fluidity, which is a special characteristics of fluid and the magneticism , which is a special one of solid. Using this characteristics, this study has been proceeded to show the basic data for developing of a viscous damper with magnetism fluid as hydraulic fluid. Experimental study shows that the application of magnetic field is effective reducing the resonance characteristics of the spring-mass system.

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A Study on the Improvement of Performance for High Speed Cutting Tool using Magnetic Fluid Polishing Technique (자기연마기술을 이용한 고속절삭공구의 성능향상에 관한 연구)

  • Cho, Jong-Rae;Yang, Sun-Cheul;Jung, Yoon-Gyo
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.1
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    • pp.32-38
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    • 2006
  • The magnetic fluid polishing technique can polish the tool of complex shape, because the polishing method which polishes as compress the workpiece by the magnetism abrasives to arrange to the linear according to the line of magnetic force. Therefore, we producted the magnetic fluid polishing device in order that mirror like finishing processes the tool surface. In order to a polishing condition selection, polishing characteristic was estimated by polishing conditions which are magnetic flux density, polishing speed, grain size, magnetic fluid. The tool was polished to the selected polishing condition. The result to evaluate the polished tool's performance with the cutting force and tool wear, the polished tool's performance was improved compared with the tool not to polish.

Development of CAE tool for reducing vibration of pipe-mount system conveying fluid (유동이 있는 배관-마운트 계의 진동저감설계 CAE Tool개발)

  • Lee, Seong-Hyeon;Jeon, Su-Hong;Jeong, Weui-Bong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.11a
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    • pp.472-473
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    • 2008
  • In this research, the finite element model is formulated taking into consideration of the effects of the fluid flow in a pipe. The characteristic of vibration is presented using mass, damping and stiffness matrix in the finite element equation of this pipe system. The displacement distribution of pipe system caused by fluid force is discussed. The method for optimizing the location of mount and the value of mount stiffness to reduce the vibration of pipe system is introduced.

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Mount design to reduce the vibration of pipe system conveying fluid (유체를 운반하는 배관계의 진동 저감을 위한 마운트 설계)

  • Lee, Seong-Hyeon;Jeong, Weui-Bong;Jeong, Cheol-Ung;Ham, Il-Bae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1437-1441
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    • 2007
  • This paper formulates the finite element model is formulated taking into consideration of the effects of the fluid flow in a pipe. The characteristic of vibration is presented using mass, damping and stiffness matrix in the finite element equation of this pipe system. The displacement distribution of pipe system caused by fluid force is discussed. The variation of vibration of a pipe system according the change of mount stiffness is discussed.

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