• 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.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.557-563
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• 2007

Rain-wind induced cable vibration can cause serious problems in cable-stayed bridge. External dampers attached to the cables have become widely accepted as an effective means for stay-cable vibration suppression. For very long stay-cables, however, such damper systems are rendered ineffective, as the dampers need be attached near the end of cables for aesthetic reasons. A recent study by the authors proposed that a movable anchorage system is replaced direct fixed support of the cable with a support through a bearing and damper. This paper extends the previous work by adding active control system to mitigate the cable vibration. The response of a cable with the proposed active control system is obtained and then compared to those of the cable with and without an external passive damper. The results show that the active control system can provide superior protection than the passive control system for a cable vibration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.139-145
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• 2018

An outrigger system is used widely to increase the lateral stiffness of high-rise buildings, resulting in reduced dynamic responses to seismic or wind loads. Because the dynamic characteristics of earthquake or wind loads are quite different, a smart vibration control system associated with an outrigger system can be used effectively for both seismic and wind excitation. In this study, an adaptive smart structural control system based on an outrigger damper system was investigated for the response reduction of multi-hazards, including seismic and wind loads. A MR damper was employed to develop the smart outrigger damper system. Three cities in the U.S., L.A., Charleston, and Anchorage, were used to generate multi-hazard earthquake and wind loads. Parametric studies on the MR damper capacity were performed to investigate the optimal design of the smart outrigger damper system. A smart control algorithm was developed using a fuzzy controller optimized by a genetic algorithm. The analytical results showed that an adaptive smart structural control system based on an outrigger damper system can provide good control performance for multi-hazards of earthquake and wind loads.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1511-1517
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• 2008

The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. The magneto-rheological fluid damper, which uses such characteristics of the fluid, generates shear force due to the fluid's cohesiveness. The core can be said to determine the magneto-rheological fluid damper's performance. This study uses the finite element analysis to compare the performance of different electromagnetic forces, which are affected by the shapes of the coil, and thus to find the optimum design for the core. In addition, as a step to construct a high-efficient damper, we suggest a type of damper that can control multiple coils and compares the performance of this damper and that of the standard damper by comparing the performance of their electro-magnetic fields.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.6
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• pp.381-386
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• 2022

This paper details the analytical and experimental studies performed to propose a steel damper based on the flexural yielding mechanism. The damper is composed of a set of damping plates that are designed to yield in flexure. The comparison of experimental and finite element analysis results indicate that the analytical approach adopted in this study should be appropriate to perform sensitivity studies on the geometries of the damping plates. Although the damper is originally proposed to work based on the flexural mechanism, it is observed that the contribution of the tensile behavior of the damping plate could be considerable. As the thickness of the damping plate increases, the plastic energy due to the flexural yield increases. As the thickness of the damping plate decreases, the contribution of the tensile behavior increases, and the shape of the hysteresis loop distorts.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.685-690
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• 2008

Recently, as large structures become lighter and more flexible, the necessity of structural control for reducing excessive displacement and acceleration due to seismic excitation is increased. As a means to minimize seismic damages, various base isolation systems are adopted or considered for adoption. In this study, a base isolation system using hysteretic damper is shown to effectively protect structures against earthquakes. A mechanical model is determined that can effectively portray the behavior of a typical E-shape device. Comparison with experimental results for a hysteretic damper indicates that the model is accurate over a wide range of operating conditions and adequate for analysis. The seismic performance of hysteretic dampers are studied and compared with the conventional systems as a base isolation system. A five-story building is modeled and the seismic performance of the systems subjected to three different earthquake is compared. The results show that the hysteretic damper system can provide superior protection than the other systems for a wide range of ground motions.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.160-168
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• 1998

In this paper. the Joint reaction forces in the suspension system of a passenger car are determined to calculate the deflections and stresses in the damper strut. A mathematical model of the Roll Stabilizer Bar(RSB) is developed to include the RSB forces in the dynamics analysis. Using these RSB forces, the variations of the damper forces and spring forces due to the wheel strokes are determined in a McPherson strut suspension. The graphs of shear force diagram, bending moment diagram, bending stress and deflections are drawn by the calculated joint reaction forces.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.945-950
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• 2007

This paper presents the design study of a rotary MRF(Magneto-Rheological Fluid) damper that can be conveniently used in the joints to control the damping torques. The basic design concept is to determine the geometric design variables allowing the magnetic flux to flow across the same sectional areas under volume constraint condition. The effects of each design variables for generating the torques were investigated by magnetic field analyses.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.6
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• pp.470-477
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• 2004

This study shows the design process of a MR damper for semi-active suspension systems. Damping force characteristics of the designed damper was predicted through the flow analysis and magnetic analysis. The predicted results were compared with the experimental results and the initial design specification was modified according to the results.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.6
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• pp.105-112
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• 2003

This paper presents the numerical design technology of a passive orifice fluid damper system especially for the characteristics between the damper piston velocity and the damping force. Numerical analysis with the visual interfacial modeling technique was applied into the analysis of the damper system's dynamics. A prototype orifice fluid damper was manufactured and experimentally tested to validate the numerical simulation results. The performances of various damper system schemes were investigated based on the verified numerical simulation model of orifice fluid damper.