The smart passive system consisting of a magnetorheological (MR) damper and an electromagnetic induction (EMI) part
has been recently proposed. An EMI part can generate the input current for an MR damper from vibration of a structure
according to Faraday's law of electromagnetic induction. The control performance of the smart passive system has been
demonstrated mainly by numerical simulations. It was verified from the numerical results that the system could be
effective to reduce the structural responses in the cases of civil engineering structures such as buildings and bridges. On
the other hand, the experimental validation of the system is not sufficiently conducted yet. In this paper, the feasibility of
the smart passive system to real-scale structures is investigated. To do this, the large-scale smart passive system is
designed, manufactured, and tested. The system consists of the large-capacity MR damper, which has a maximum force
level of approximately ±10,000N, a maximum stroke level of ±35mm and the maximum current level of 3 A, and the
large-scale EMI part, which is designed to generate sufficient induced current for the damper. The applicability of the
smart passive system to large real-scale structures is examined through a series of shaking table tests. The magnitudes of
the induced current of the EMI part with various sinusoidal excitation inputs are measured. According to the test results,
the large-scale EMI part shows the possibility that it could generate the sufficient current or power for changing the
damping characteristics of the large-capacity MR damper.
This paper describes the design of an electromagnetic induction (EMI) system and its application to powering a low
force profile Magneto-Rheological (MR) damper. The EMI system is capable of converting vibration energy into useful
electric energy for use in actuating the MR damper as the sole power source. An EMI prototype, consisting of an
electromagnet and a permanent magnet, was designed and constructed. The EMI prototype was then attached to an
existing MR damper, making an MR-EMI system. Using this system, an experimental study was performed to evaluate
the dynamic performance of the MR-EMI system in a laboratory environment.
This paper investigates the feasibility and efficacy of an MR damper-based control system introducing an electromagnetic induction (EMI) part, for suppressing vibration of building structures subjected to seismic loadings. In the proposed control system, the EMI part composed of a permanent magnet and a coil converts the kinetic energy of the relative motion between a building and a damper into the electric energy, which is used for a change in damping characteristics of the MR damper. Since the EMI part can be used as a controller, which determines the command voltage input according to structural responses, as well as a power source, the proposed control system can be much more compact, convenient, and economic than a conventional active/semiactive system that needs a power supply, a controller and sensors. To verify the feasibility and efficacy of the proposed control system, a shaking table test of a small-scale building model employing the MR damper with the EMI part is conducted. The performance of the proposed control system is compared with that of conventional semiactive control systems using an MR damper.
This paper presents a smart passive damping system (SPDS) for reducing stay cable vibrations. Stay cables, such as used in cable-stayed bridges, are prone to vibration due to their low inherent damping characteristics. Recently some studies have shown that semiactive control systems using Magnetorheological(MR) dampers can potentially achieve higher performance levels and adaptability with few of the detractions as compared their passive counterparts. However, most semi-active and active control systems that use MR dampers require additional power supplies, controllers, and sensors, adding complexity into the system. The complexity may not be desirable to effectively control many large civil structures. This paper proposes a novel SPDS with MR dampers. The smart passive device includes an electromagnetic induction (EMI) system to power the MR damper and adjust itself to external loadings. Thus, SPDS dose not require any control system. The numerical study considered 12.56m stay cable to evaluate the dynamic performance of the SPDS for mitigating the vibration of stay cables. Moreover, the performances of the smart passive damping system are compared with those of an equivalent linear viscous damper and an MR damper operated in a pssive-mode. Results showed SPDS has competitive performance with others despite of its simplicity.