• Title, Summary, Keyword: Damper

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Damping updating of a building structure installed with an MR damper

  • Woo, Sung-Sik;Lee, Sang-Hyun
    • Smart Structures and Systems
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    • v.12 no.6
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    • pp.695-705
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    • 2013
  • The purpose of this paper is to identify through experiments the finite element (FE) model of a building structure using a magnetorheological (MR) fluid damper. The FE model based system identification (FEBSI) technique evaluates the control performance of an MR damper that has nonlinear characteristics as equivalent linear properties such as mass, stiffness, and damping. The Bingham and Bouc-Wen models were used for modeling the MR damper and the equivalent damping increased by the MR damper was predicted by applying an equivalent linearization technique. Experimental results indicate that the predicted equivalent damping matches well with the experimentally obtained damping.

Research for the Pulsating Pressure Characteristics by a Damper and an Accumulator in the High Frequency Hydraulic System (고주파 유압시스템에서 감치장치와 축압기에 의한 맥동 충격파 감쇄특성에 대한 연구)

  • Kim, Yang-Soo;Kim, Jae-Soo;Rho, Hyung-Woon
    • 유체기계공업학회:학술대회논문집
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    • pp.641-647
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    • 2004
  • Characteristics of the high frequency pulsatile flow have been investigated experimentally to understand the flow phenomena in the hydraulic system. The accumulator in high frequency hydraulic system but that is not effective all frequency zone. Therefore, a hydraulic damper used with accumulator is suggested to reduce the high frequency pulsatile where the accumulator is not effective. The pulsating pressure obtained by Pressure measurement system are analyzed to power spectral density distribution. According to the variations of pump input pressure and actuator acceleration frequency, the pressure is measured with or without an accumulator or pulsatile damper The amplitude of pressure with damper is very lower than those without accumulator or damper due to absorbing function of damper. As the frequency of actuator acceleration is increased, the effect of damper becomes very important to decrease the amplitude of pulsatile Pressure waveform with high frequencies.

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Study of the non-linearity of cable damper to enhance damping performance of stay cable (사장교 케이블의 감쇠성능 향상을 위한 댐퍼의 비선형성 연구)

  • Seo, Ju-Won;Koh, Hyun-Moo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.147-156
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    • 2007
  • This study offers a design procedure of optimum cable damper for multi-mode vibration control with nonlinear damper and also investigate the relation between mode and amplitude dependency. The proposed multi-mode damping index, which is defined as a energy loss ratio of cable potential, is a main component of optimization problem of optimum nonlinear damper. In order to include the amplitude dependency of nonlinear damper, it is assumed to exist three kinds of multi-mode patterns such as ambient vibration, support excitation and rain-win induced vibration. The optimum damper exponent depends on amplitude patterns. In case of ambient vibration, optimum factor is less than 0.5. In case of support excitation or rain-wind induced vibration is between 0.5 and 1.0. In this study, the effects of cable sag and inclination angle are included in the asymptotic design equation of damped cable structures.

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A Experiment of the damping effect for Electromagnetic Damper using DC Motor and Ballscrew (DC Motor와 Ballscrew를 이용한 Electromagnetic Damper Damping 효과 실험)

  • Kang, Jeong-Ho;Lee, Hac-Choel;Jeong, Young-Suk
    • Proceedings of the KIPE Conference
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    • pp.124-126
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    • 2008
  • In this Paper, the modeling of the electromagnetic damper for automobile suspension is presented and the validation of the model is demonstrated by experiments. An electromagnetic damper, composed of a rotary DC motor, and a ball screw and nut. The damper then operates as a linear electric actuator. The damper then operate as a linear electric actuator. The results indicate the proposed system is feasible and it is proved that the electromagnetic damper has better than oil damper of passive control system.

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Design of MR damper with multi_stage core (다중 자기 코일 작동기를 사용한 MR damper의 설계해석)

  • Lee, Gyu-Seop;Yoo, Won-Hee;Ryu, Bong-Jo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.525-528
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    • 2008
  • The dynamic range of MR damper is the most important characteristics for the usage of semi-active control system. The damping force can be increased by simply decresing the orifice gap in the traditional oil damper, but it deteriorate the dynamic range in MR damper. In this paper, the multi-stage electro-magnetic core is suggested to maintain the performance of MR damper with a large damping force. The MR damper with 3 stage core is designed and manufactured for testing and analysis.

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Mechanical Characteristics Analysis of Coil Spring & Viscous Damper System (Coil Spring & Viscose Damper System의 동적거동특성분석)

  • Kim, Min-Kyu;Choun, Young-Sun
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.471-478
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    • 2006
  • This paper presents the results of experimental studies of the mechanical characteristics of the Coil Spring and Viscous Damper system. The Coil Spring and Viscous Damper systems were selected for the isolation of Emergency Diesel Generator (EDG) which is located in Nuclear Power Plant (NPP). The Coil Spring and Viscous Damper systems were developed for, the operating vibration isolation and seismic isolation for scaled Model EDG System. The damping properties of the viscous damper changes as the variation of velocity. As a results, nonlinear damping characteristics of viscous damper system were evaluated.

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Comparison of Performances refer to Magnetic and Fluid Analysis of Magneto-Rheological Flow Damper (자기점성유체 댐퍼의 자기장 및 유동 해석에 따른 성능비교)

  • Song, Jun-Han;Son, Sung-Wan;Lee, Gyu-Seop;Chun, Chong-Keun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.98-102
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    • 2009
  • The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. To manufacture the magneto-rheological fluid damper that uses such characteristics of the fluid, a flow analysis of the inner damper was conducted to forecast the damper's capacity. In addition, using the finite element method software, analysis on the characteristics of electromagnetic field around the coil operation unit inside the damper. Based on the result of the analysis, a single core damper and a double core damper were built and tested for their dynamic function. Based on the result of the experiment, the propriety of the flow analysis was demonstrated, and the proposed model was verified.

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Experimental research of dynamic behaviors at viscoelastic damper with change of orifice (점탄성 감쇠기의 간극 변화에 따른 동특성에 대한 실험적 연구)

  • Yun, Jong-Min;Lim, Sang-Hyuk;Park, Hwa-Yong;Kim, Chang-Yeol;Lee, Jae-Eung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.744-749
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    • 2011
  • Silicon oil in viscous fluid damper has a viscoelastic feature that show stiffness besides damping. These properties depend on frequency and are non-linear. A lot of research has been conducted in order to identify viscoelastic damper with mathematical model. Fractional Derivative Maxwell Model has been widely used, but this model did not explain the effect of damper size change on the damper performance. In this paper, the experimental study was conducted to validate damper's dynamic behaviors when total damper's size is changed while maintaining same aspect ratio and orifice size.

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A Study on the Optimization Design of Automotive Damper Using Genetic Algorithm (유전알고리즘을 이용한 차량용 댐퍼의 최적설계에 관한 연구)

  • Lee, Choon-Tae
    • Journal of Power System Engineering
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    • v.22 no.6
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    • pp.80-86
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    • 2018
  • A damper is a hydraulic device designed to absorb or eliminate shock impulses which is acting on the sprung mass of car body. It converts the kinetic energy of the shock into another form of energy, typically heat. The main mechanism for providing damping is by shearing the hydraulic fluid as it flows through restrictions. Since the damping mechanism depends on the flow restrictions, these restrictions are very important in damper design. Damper engineers often try several combinations of valve shims, piston orifices and bleed orifices before finding the best combination for a particular setup on a car. Therefore, the ability to tune a damper properly without testing is of great interest in damper design. For this reason, many previous researches have been done on modeling and simulation of the damper. This paper explains a genetic algorithm method to find the optimal parameters for the design objective and the simulation results agree well with the targeted damping characteristics.

Analysis of Magnetic Field of Superconducting Winding According to the Changed Damper Thickness and Material (댐퍼의 두께와 재질 변화에 따른 초전도 선재에 미치는 자장특성 분석)

  • Jeong, Jae-Sik;Lee, Sang-Ho;Hong, Jung-Pyo;Jo, Young-Sik
    • Progress in Superconductivity and Cryogenics
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    • v.14 no.3
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    • pp.5-8
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    • 2012
  • Superconducting windings of synchronous machine have to be operated in below the critical temperature, critical current density and critical magnetic field. If one of these characteristics does not satisfied, then the quench occurred in superconducting winding. Especially the armature current dramatically increased as the superconducting generator is short-circuited at the rated load condition and magnetic field in field winding increased due to the armature current. Therefore, damper is required to reduce the magnetic field of field winding which increases reliability of the superconducting generator. Damper dimension can be decided by time constant[1-2]. In this paper the basic model is high-power and low-speed superconducting generator. Damper time constant was calculated from the changed damper thickness and material. Magnetic flux of field coil at the basic model and changed damper time constant model is analyzed.