• Title, Summary, Keyword: Damping force

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Control of Damping Coefficients for the Shear Mode MR Dampers Using Inverse Model (역모델을 이용한 MR 댐퍼의 감쇠계수 제어)

  • Na, Uhn Joo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.5
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    • pp.445-455
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    • 2013
  • A new linearization model for MR dampers is analyzed. The nonlinear hysteretic damping force model of MR damper can be modeled as a hyperbolic tangent function of currents, positions, and velicities, which is an algebraic function with constant parameters. Model parameters can be identified with numerical method using experimental force-velocity-position data obtained from various operating conditions. The nonlinear hysteretic damping force can be linearized with a given slope of damping coefficient if there exist corresponding currents to compensate for the nonlinearity. The corresponding currents can be calculated from the inverse model when the given linear damping force is set equal to the nonlinear hysteretic damping force. The linearization controller is realized in a DSP controller such that the corresponding currents to satisfy a given damping coefficient should be calculated. Experiments show that the current inputs to the MR damper produce linearized damping force with a given slope of the damping coefficient.

Sloped rolling-type bearings designed with linearly variable damping force

  • Wang, Shiang-Jung;Sung, Yi-Lin;Hong, Jia-Xiang
    • Earthquakes and Structures
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    • v.19 no.2
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    • pp.129-144
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    • 2020
  • In this study, the idea of damping force linearly proportional to horizontal isolation displacement is implemented into sloped rolling-type bearings in order to meet different seismic performance goals. In addition to experimentally demonstrating its practical feasibility, the previously developed analytical model is further modified to be capable of accurately predicting its hysteretic behavior. The numerical predictions by using the modified analytical model present a good match of the shaking table test results. Afterward, several sloped rolling-type bearings designed with linearly variable damping force are numerically compared with a bearing designed with conventional constant damping force. The initial friction damping force adopted in the former is designed to be smaller than the constant one adopted in the latter. The numerical comparison results indicate that when the horizontal isolation displacement does not exceed the designed turning point (or practically when subjected to minor or frequent earthquakes that seldom have a great displacement demand for seismic isolation), the linearly variable damping force design can exhibit a better acceleration control performance than the constant damping force design. In addition, the former, in general, advantages the re-centering performance over the latter. However, the maximum horizontal displacement response of the linearly variable damping force design, in general, is larger than that of the constant damping force design. It is particularly true when undergoing a horizontal isolation displacement response smaller than the designed turning point and designing a smaller value of initial friction damping force.

A Study on the Application of Semi-active Suspension System to a 3-D Full Vehicle Model (전차 모델에 대한 반능동 현가장치의 적용에 대한 연구)

  • 방범석;백윤수;박영필
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.938-944
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    • 1994
  • Active damping has been shown to offer increased suspension performance in terms of vehicle isolation, suspension packaging, and road-tire contract force. Many semi-active damping strategies have been introduced to approximate the response of active damping with the modulation of passive damping parameters. This study investigates the characteristics of semi-active suspension control through the simulation of passive, skyhook active, and semi-active damping models. A quarter car model is studied with the conrolled damping replacing both passive and active damping. A new semi-active scheme is suggested to eliminate the abrupt changes in semi-active damping force. It is shown that the new strategy performs almost identically to the so called "force controlled" semi-active law without steep changes in damping force or body acceleration.eleration.

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A Study of Electrical Control Kit for Damping Force of Automotive Shock Absorber (자동차 충격흡수장치용 감쇠력 조정 전자제어장치 연구)

  • Sohn, Il-Seon;Lee, Jeong-Goo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.3
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    • pp.1-6
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    • 2008
  • The performance of shock absorber is directly related to the car behavior and performance, both for handling and comfort. Most of compact car are assembled the passive shock absorber for cost effect but some of compact driver want better performance of shock absorber than standard parts. Therefore, they want the semi-active suspension control system instead of standard damper system. But they only can change the mechanical damping control shock absorber at A/S market. The mechanical damping control shack absorber can not vary the damping force in driving condition so they do not satisfy the mechanical damping control shock absorber system. In this study, electrically damping force controlled shock absorber system is developed based on the mechanical damping force control damper system. This system can vary damping force by switch on dashboard in driving condition. And, this system can satisfy the requirement of tuning market. Therefore, it is expected the system to show the engineering capability of korean damper company and to increase export market share to oversea damper market.

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.

Experimental Study on Energy Dissipation Capacities of the Viscous Damping Wall (벽식점성감쇠기의 감쇠 성능에 관한 기초적인 연구)

  • 이장석;김남식;조강표
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.246-251
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    • 2003
  • This paper presents an experimental study on the energy dissipation characteristics of viscous damping wall (VDW). VDW is consisted of a plate floating in a thin case made of steel plated filled with highly viscous silicone oil. Because VDW demonstrates both viscous damping and stiffness characteristics, the viscous resisting force can be expressed as the sum of velocity dependant viscous damping force and displacement dependant restoring force. The viscous resisting force and energy absorbing capacity can be easily adjusted by changing three factors, i.e. viscosity of the fluid, gap distance and area of the wall plates. VDW was tested using a series of harmonic (sinusoidal) displacement history having different frequency and amplitude and the force-displacement relationship was recorded. The relationship between dissipated energy with three factors and the influence of exciting frequency on resisting force were Investigated

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Damping Force Characteristics of ER Damper Considering Hysteresis (ER 댐퍼의 이력현상을 고려한 댐핑력 특성 고찰)

  • 홍성룡;송현정;한상수;최승복
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.489-494
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    • 2002
  • This paper presents hydraulic model which can capture the hysteric damping force behavior of ER damper. A flow mode rue ER damper is manufactured, and its field-dependent damping forces are measured. Newly proposed hydraulic model which derived from physical hydro-mechanical parameters of ER damper are conventional Bingham model are investigated to represent the field-dependent damping force characteristics of ER damper. After principal parameters of two models are estimated from the measured damping forces data, the force vs velocity hysteresis cycles are then reconstructed. The results show that the proposed hydraulic model can capture the hysteresis behavior of ER damper accurately.

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An Investigation into the Effect of Each Parameter of S/A on the Damping Force Using Dynamic Behaviour Analysis P/G (충격 흡수기의 동적거동 해석 프로그램을 이용한 각 파라미터가 댐핑력에 미치는 영향 조사)

  • 박재우;신상윤;주동우;이시복
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.371-376
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    • 1996
  • The damping force of shock absorber in an automobile is determined by the components which construct the S/A. In this study we investigate the individual effect of these components on damping force. In addition, opening of important valve doling compression and tension cycle due to up-down reciprocation movement is also researched. Thus we are to strictly control the properties and tolerance of components having important effects on tile damping force and to produce S/A of better quality.

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Structural Damping Effects on Stability of a Cantilever Column under Sub-tangentially Follower Force (종동력을 받는 외팔기둥의 동적 안정성에 미치는 구조감쇠 효과)

  • Min, Dong-Ju;Park, Jae-gyun;Kim, Moon-Young
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.6_spc
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    • pp.635-643
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    • 2016
  • A stability theory of a damped cantilever column under sub-tangential follower forces is first summarized based on the stability map. It is then demonstrated that internal and external damping can be exactly transformed to Rayleigh damping so that the damping coefficients can be effectively determined using proportional damping. Particularly a parametric study with variation of damping coefficients is performed in association with flutter loads of Beck's column and it is shown that two damping coefficients can be correctly estimated for real systems under the assumption of Rayleigh damping. Finally a frequency equation of a cantilever beam subjected to both a sub-tangentially follower force and two kinds of damping forces is presented in the closed-form and its stability maps are constructed and compared with FE solutions in the practical range of damping coefficients.

A study on Dynamic Characteristics of an Eddy Current Damping (와전류감쇠기의 동특성에 관한 연구)

  • Park, Jungsam;Bae, Jaesung;Hwang, Jaihyuk;Kang, Kukjeong
    • Journal of Aerospace System Engineering
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    • v.2 no.3
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    • pp.24-28
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    • 2008
  • Eddy current are induced when a nonmagnetic, conductive material is moving as the result of being subjected to the magnetic field, or if it is placed in a time-varying magnetic field. These currents circulate in the conductive material and are dissipated, causing a repulsive force between the magnet and conductor. Using this concept, eddy current damping can be used as a form of viscous damping. This paper investigated analytically and experimentally the characteristics of an eddy current damping when a permanent magnet is placed in a conductive tube. The theoretical model of the eddy current damping is developed from electromagnetics and is verified from Maxwell program and experiments. From these comparisons, although predictability is not accurate at high excitation frequencies, the present model can be used to predict damping force at low excitation frequencies. In order to improve the prediction of the characteristics of an eddy current damping, the induced magnetic flux densities have to be considered in following researches.

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