• Title, Summary, Keyword: MR damper

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Damping Force Characteristics of MR Damper with Additional Flow Path (부가적인 유로가 있는 MR 댐퍼의 감쇠력 특성)

  • Sohn, Jung Woo;Oh, Jong-Seok;Choi, Seung-Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.6
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    • pp.426-431
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    • 2015
  • In this work, a new type of MR damper with additional flow path in piston is proposed and damping force characteristics are numerically evaluated. Flow-mode type MR damper is considered and mathematical model is established based on Bingham rheological model of MR fluid to obtain accurate prediction of damping force characteristics. Damping force of the proposed MR damper are calculated with respect to piston velocity and input current. In addition, investigation on damping force characteristics is carried out according to number of additional flow path and excellence of the proposed MR damper is demonstrated.

Calculating a MR Damper's Optimal Capacity for a Control of Structural Vibration (구조물의 진동제어를 위한 MR-damper의 최적 제어력 산정)

  • Heo, Gwanghee;Jeon, Seunggon;kim, Chunggil;Jeon, Joonryong;Lee, Chinok;Seo, Sanggu
    • Journal of the Earthquake Engineering Society of Korea
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    • v.20 no.3
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    • pp.163-169
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    • 2016
  • In the case where a MR-damper is employed for vibration control, it is important to decide on how much control capacity should be assigned to it against structural capacities (strength and load, etc). This paper aims to present a MR-damper's control capacity suitable for the capacities of the structure which needs to be controlled. First, a two span bridge was built equipped with a MR-damper, which constitutes a two-span MR-damper control system. Then, inflicting an earthquake load on the system, a basic experiment was performed for vibration control, and a simulation was also carried out reflecting specific control conditions such as MR-damper and rubber bearing. The comparison of the results against each other proved their validity. Then, in order to calculate an optimal control capacity of the MR-damper, structural capacity was divided into eleven cases in total and simulated. For each case, an additional load of 30 KN was inflicted everytime, thereby increasingly strengthening structural capacity. As a result of the study, it was found that the control capacity of MR-damper of 30 KN was safely secured only with lumped mass of more than 150 KN(case 6). Therefore, it is concluded the MR-damper showed the best performance of control when it exerted its capacity at around 20% of structural capacity.

Control Performance Investigation of MR Fluid Damper using Herschel-Bulkley Shear Model (Herschel-Bulkley 모델을 이용한 MR 댐퍼 승용차의 제어 성능 고찰)

  • 이덕영;황우석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.323-328
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    • 2002
  • The control performance of a vehicle installed with an MR(magnetorheological) fluid-based damper is investigated on the basis of Herschel-Bulkley shear model. Generally, most of MR fluid damper has been analyzed based on a simple Bingham-plastic shear model. However, the Bingham-plastic shear model can not well describe the behavior of the damper on the condition of high velocity and high current field input. Therefore, in this study, the Herschel-Bulkley shear model in which the constant post-yield plastic viscosity in Bingham model is replaced with a power law model dependent on shear rate is used to assess control performance of a vehicle with MR fluid damper suspension system. This study deals with a two-degree-of-freedom suspension using the MR fluid damper for a quarter car model. The response for the bump input to identify the fastness of MR fluid damper embedded skyhook controller and requested magnetic field are investigated.

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Smart Passive System Based on MR Damper (MR댐퍼 기반의 스마트 수동제어 시스템)

  • Cho, Sang-Won;Jo, Ji-Seong;Kim, Chun-Ho;Lee, In-Won
    • Journal of the Earthquake Engineering Society of Korea
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    • v.9 no.1
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    • pp.51-59
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    • 2005
  • Magnetorheological(MR) dampers are one of the most promising semi active control devices, because they have advantages such as small power requirement, reliability, and low price to manufacture. To reduce the responses of structures with MR dampers, a control system including power supply, controller, and sensors is required. However, when a mount of MR dampers are used to a large?scale civil structure such as cable stayed bridges, the control system becomes complex. Therefore, it is not easy to install and maintain the MR damper based control system. To resolve above difficulties, This paper proposes a smart passive system that consists of a MR damper and an electromagnetic induction(EMI) system. According to the Faraday’s law of induction, EMI system that is attached to the MR damper produces electric energy. The produced energy is supplied to the MR damper. Thus, the MR damper with EMI system does not require any power at all. Furthermore, the induced electric energy is proportional to external loads like earthquakes, which means the MR damper with EMI system is adaptable to external loads without any controller and corresponding sensors. Therefore, it is easy to build up and maintain the proposed smart passive system.

Performance Evaluation of Commercial Vehicle with MR Seat Damper (MR 시트댐퍼를 장착한 상용차의 제어성능 평가)

  • 성금길;이호근;남무호;최승복
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1048-1053
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    • 2003
  • This paper proposed a MR(Magneto-rheological) seat damper for a commercial vehicle. After formulating the governing equation of motion, an appropriate size of damper is designed and manufactured. Following the equation of fie d-dependent damping force characteristics, a semi-active seat suspension installed with the proposed MR-damper is constructed and its dynamic model id established, Subsequently, vibration isolation performance of the semi-active suspension system is demonstrated by incorporating with a MRAC(Model referenced adaptive control) fer the MR Seat Damper

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Magneto-rheological and passive damper combinations for seismic mitigation of building structures

  • Karunaratne, Nivithigala P.K.V.;Thambiratnam, David P.;Perera, Nimal J.
    • Earthquakes and Structures
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    • v.11 no.6
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    • pp.1001-1025
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    • 2016
  • Building structures generally have inherent low damping capability and hence are vulnerable to seismic excitations. Control devices therefore play a useful role in providing safety to building structures subject to seismic events. In recent years semi-active dampers have gained considerable attention as structural control devices in the building construction industry. Magneto-rheological (MR) damper, a type of semi-active damper has proven to be effective in seismic mitigation of building structures. MR dampers contain a controllable MR fluid whose rheological properties vary rapidly with the applied magnetic field. Although some research has been carried out on the use of MR dampers in building structures, optimal design of MR damper and combined use of MR and passive dampers for real scale buildings has hardly been investigated. This paper investigates the use of MR dampers and incorporating MR-passive damper combinations in building structures in order to achieve acceptable levels of seismic performance. In order to do so, it first develops the MR damper model by integrating control algorithms commonly used in MR damper modelling. The developed MR damper is then integrated in to the seismically excited structure as a time domain function. Linear and nonlinear structure models are evaluated in real time scenarios. Analyses are conducted to investigate the influence of location and number of devices on the seismic performance of the building structure. The findings of this paper provide information towards the design and construction of earthquake safe buildings with optimally employed MR dampers and MR-passive damper combinations.

Equivalent damping ratio based on earthquake characteristics of a SDOF structure with an MR damper (지진특성에 따른 MR 감쇠기가 설치된 단자유도 구조물의 등가감쇠비)

  • Moon, Byoung-Wook;Park, Ji-Hun;Lee, Sung-Kyung;Min, Kyung-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.459-464
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    • 2007
  • Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. Frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally, response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

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Equivalent damping ratio based on the earthquake response of a SDOF structure with a MR damper (MR 감쇠기가 설치된 단자유도 구조물의 지진응답에 기초한 등가감쇠비)

  • Park, Ji-Hun;Moon, Byoung-Wook;Min, Kyung-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.879-885
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    • 2006
  • Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally, response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

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Equivalent Damping Ratio Based on Earthquake Characteristics of a SDOF Structure with an MR Damper (지진특성에 따른 MR감쇠기가 설치된 단자유도 구조물의 등가감쇠비)

  • Moon, Byoung-Wook;Park, Ji-Hun;Lee, Sung-Kyung;Min, Kyung-Won
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.1
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    • pp.87-93
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    • 2008
  • Seismic control performance of MR dampers, which have severe nonlinearity, varies with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. Frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally. response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.