• Title, Summary, Keyword: MR damper

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Performance Evaluation of Decentralized Control Algorithm of a Full-scale 5-story Structure Installed with Semi-active MR Damper Excited by Seismic Load (준능동 MR감쇠기가 설치된 실물크기 구조물의 분산제어 알고리즘 성능평가)

  • Youn, Kyung-Jo;Park, Eun-Churn;Lee, Heon-Jae;Moon, Seok-Jun;Min, Kyung-Won;Jung, Hyung-Jo;Lee, Sang-Hyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.2
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    • pp.255-262
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    • 2008
  • In this study, seismic response control performance of decentralized response-dependent MR damper which generates the control force using only the response of damper-installed floor, was experimentally investigated through the tests of a full-scale structure installed with large MR dampers. The performance of the decentralized control algorithm was compared to those of the centralized ones such as Lyapunov, modulated homogeneous friction, and clipped-optimal control. Hybrid mass damper were controlled to induce seismic response of the full-scale structure under El Centro earthquake. Experimental results indicated that the proposed decentralized MR damper provided superior or equivalent performance to centralized one in spite of using damper-installed floor response for calculating input voltage to MR damper.

Incorporating magneto-Rheological damper into riser tensioner system to restrict riser stroke in moderate-size semisubmersibles

  • Zainuddin, Zaid;Kim, Moo-Hyun;Kang, Heon-Yong;Bhat, Shankar
    • Ocean Systems Engineering
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    • v.8 no.2
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    • pp.101-118
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    • 2018
  • In case of conventional shallow-draft semisubmersibles, unacceptably large riser stroke was the restricting factor for dry-tree-riser-semisubmersible development. Many attempts to address this issue have focused on using larger draft and size with extra heave-damping plates, which results in a huge cost increase. The objective of this paper is to investigate an alternative solution by improving riser systems through the implementation of a magneto-rheological damper (MR Damper) so that it can be used with moderate-size/draft semisubmersibles. In this regard, MR-damper riser systems and connections are numerically modeled so that they can couple with hull-mooring time-domain simulations. The simulation results show that the moderate-size semisubmersible with MR damper system can be used with conventional dry-tree pneumatic tensioners by effectively reducing stroke-distance even in the most severe (1000-yr) storm environments. Furthermore, the damping level of the MR damper can be controlled to best fit target cases by changing input electric currents. The reduction in stroke allows smaller topside deck spacing, which in turn leads to smaller deck and hull. As the penalty of reducing riser stroke by MR damper, the force on the MR-damper can significantly be increased, which requires applying optimal electric currents.

Seismic Performance Assessment of a Nonlinear Structure Controlled by Magneto-Rheological Damper Using Multi-Platform Analysis (자기유변댐퍼로 제어되는 비선형 구조물의 멀티플랫폼 해석을 이용한 내진성능평가)

  • Kim, Sung Jig
    • Journal of the Earthquake Engineering Society of Korea
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    • v.17 no.3
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    • pp.143-150
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    • 2013
  • The paper introduces Multi-Platform Analysis (MPA) for the seismic performance of a structure controlled by Magneto-Rheological (MR) dampers and presents analytical assessment of the effect of MR damper when taking into account nonlinear behavior of the structure. This paper introduces the MR Damper Plugin that can facilitate communication between MATLAB/Simulink and a finite element analysis tool in order to account for more complex inelastic behavior of the structure with MR dampers. The MPA method using the developed MR Damper Plugin is validated with experimental results from the real-time hybrid simulation. By utilizing the proposed MPA method, the three-story RC structure controlled by MR dampers is more realistically modeled and its performance under seismic loads is investigated. It is concluded that MR damper designed for a linear structure is not effective in a nonlinear structure and can overestimate the effect of MR damper. This work is expected to overcome difficulties in the analytical assessment of structural control strategies for complex and nonlinear structures by obtaining more reliable results.

Phenomenological Damping Flow Modeling and Performance Evaluation for a Continuous Damping Control Damper Using MR Fluid (MR 유체를 이용한 연속 감쇠력 가변형 댐퍼를 위한 감쇠유동의 현상학적 모델링과 성능평가)

  • Park, Jae-Woo;Jung, Young-Dae
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.3
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    • pp.73-82
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    • 2008
  • Recently MR CDC damper has been applied to semi-active suspension control system gradually. Compared to former hydraulic CDC damper, it has rapid time response performance as well as simple internal structure and wide range of damping force. In order to develop control logic algorithm which enables to take maximum advantage of unique characteristics of MR CDC damper, it is inevitable to perform a thorough investigation into its nonlinear performance. In many previous researches, MR fluid model was either simply assumed as Bingham Plastic, or a phenomenological model based on experiment was established instead to predict damping performance of MR CDC damper. These experimental flow model which is not based on flow analysis but intentionally built to fit damping characteristics, may lead to totally different results in case of different configuration or structure of MR CDC damper. In this study, a generalized flow formula from mathematical flow model of MR fluid for annular orifice is derived to analyze and predict damping characteristics when current is excited at piston valve.

Study on Dynamic Absorbing System using MR Damper in High Impulsive Force System (MR 댐퍼를 이용한 고충격 시스템의 완충 특성)

  • 김효준;김상균;최의중;이성배;홍계정;오세빈
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.431-434
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    • 2002
  • In this study, the dynamic absorbing system using MR damper for the multiple structure system with high-level-impact force has been investigated. Based on the experiment and analysis of short recoil system, the dynamic absorbing system has been constructed by using MR damper and stroke-dependent variable damper. Through a series of experimental works with the devised test bench, the absorbing system with MR damper using reverse control is effective for reduction of the transmitted force, furthermore, for implementation to the multi-structure impulsive force system.

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Dynamic Characteristics Modeling for A MR Damper using Artifical Neural Network (인공신경망을 이용한 MR댐퍼의 동특성 모델링)

  • 백운경;이종석;손정현
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.3
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    • pp.170-176
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    • 2004
  • MR dampers show highly nonlinear and histeretic dynamic behavior. Therefore, for a vehicle dynamic simulation with MR dampers, this dynamic characteristics should be accurately reflected in the damper model. In this paper, an artificial neural network technique was developed for modeling MR dampers. This MR damper model was successfully verified through a random input forcing test. This MR damper model can be used for semi-active suspension vehicle dynamics and control simulations with practical accuracy.

Control of a building complex with Magneto-Rheological Dampers and Tuned Mass Damper

  • Amini, F.;Doroudi, R.
    • Structural Engineering and Mechanics
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    • v.36 no.2
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    • pp.181-195
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    • 2010
  • Coupled building control is a viable method to protect tall buildings from seismic excitation. In this study, the semi-active control of a building complex is investigated for mitigating seismic responses. The building complex is formed of one main building and one podium structure connected through Magneto-Rheological (MR) Dampers and Tuned Mass Damper. The conventional semi-active control techniques require a primary controller as a reference to determine the desired control force, and modulate the input voltage of the MR damper by comparing the desired control force. The fuzzy logic directly determines the input voltage of an MR damper from the response of the MR damper. The control performance of the proposed fuzzy control technique for the MR damper is evaluated for the control problem of a seismically-excited building complex. In this paper, a building complex that include a 14-story main building and an 8-story podium structure is applied as a numerical example to demonstrate the effectiveness of semi-active control with Magneto-Rheological dampers and its comparison with the passive control with the Tuned Mass Damper and two uncoupled buildings and hybrid semi-active control including the Tuned Mass Damper and Magneto-Rheological dampers while they are subject to the earthquake excitation. The numerical results show that semi-active control and hybrid semi-active control can significantly mitigate the seismic responses of both buildings, such as displacement and shear force responses, and fuzzy control technique can effectively mitigate the seismic response of the building complex.

Study on Performance Comparison of MR Damper for Fluid Properties and Orifice Shapes (MR 유체물성과 오리피스 형상에 대한 MR 댐퍼 성능비교 연구)

  • Kwon, Young-Chul;Park, Sam-Jin;Kim, Ki-Young;Baek, Dae-Sung;Lee, Seok-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.3
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    • pp.1305-1310
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    • 2014
  • MR(Magneto-Rheological) damper generates the magnetic shear force due to the cohesiveness of MR fluid influenced by a magnetic field. MR fluid consists of magnetic particles and a base liquid. In the present study, the damping forces of MR damper were investigated for density 1.3, 1.5 and $1.7g/cm^3$, and viscosity 1000 and 10000cp, and for the change of orifice shapes. It was found that the increase in the density and viscosity of MR fluid could change the damping force of MR damper due to the magnetic effects. Also, the damping forces on orifice shapes increased as the orifice gap and length decreased. These results showed that the properties of MR fluid and orifice shapes were important for the optimum design of MR damper.

Stability Analysis of Railway Vehicle Featuring MR Damper (MR 댐퍼를 적용한 철도차량의 안정성 해석)

  • Ha, Sung-Hoon;Choi, Seung-Bok;Yoo, Won-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.957-962
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    • 2008
  • This paper presents vibration control performances and stability evaluations of railway vehicle featuring controllable magnetorheological (MR) damper. The MR damper model is developed and then incorporated with the governing equations of motion of the railway vehicle which includes vehicle body, bogie and wheel-set. A cylindrical type of MR damper is devised and its damping force is evaluated by considering fluid viscosity and MR effect. Design parameters are determined to achieve desired damping force level applicable to real railway vehicle. Subsequently, computer simulation of vibration control and stability analysis is performed using Matlab Simulink.

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Effects of excitation characteristics on the equivalent linear system of a building structure with MR dampers (MR감쇠기가 설치된 구조물의 등가선형 시스템에 대한 가진 특성의 영향)

  • Park, Ji-Hun;Min, Kyung-Won;Moon, Byoung-Wook;Park, Eun-Churn
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.503-510
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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 an MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with an 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.

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