Theoretical Comparison of Motional and Transformer Emf Device Damping Efficiency

Graves, K. E.; Toncich, Dario J.; Iovenitti, Pio G.

doi:10.1006/jsvi.1999.2820

Cited by 49 publications

(30 citation statements)

References 5 publications

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“…The changing magnetic field may either be attributed to the relative motion between the conductor and a magnetic source or variation of the magnetic field with time. The currents generated in the former case are called motional eddy currents and those in the latter case are called transformer eddy currents . In this paper, we utilize motional eddy currents to create a braking force against the motion of the lower and upper PMs relative to the copper plate.…”

Section: Mathematical Modeling Of a Simple Pemecfdmentioning

confidence: 99%

“…The currents generated in the former case are called motional eddy currents and those in the latter case are called transformer eddy currents. [46] In this paper, we utilize motional eddy currents to create a braking force against the motion of the lower and upper PMs relative to the copper plate. Figure 5a illustrates this mechanism utilized in the simple PEMECFD.…”

Section: Eddy Current Dampingmentioning

confidence: 99%

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A passive electromagnetic eddy current friction damper (PEMECFD): Theoretical and analytical modeling

Amjadian

Agrawal

2017

Struct. Control Health Monit.

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Summary The focus of this paper is on analytical modeling of a novel type of passive friction damper for seismic hazard mitigation of structures. The proposed seismic damping device, which is termed as passive electromagnetic eddy current friction damper, utilizes a solid‐friction mechanism in parallel with an eddy current damping mechanism to maximize the dissipation of input seismic energy through a smooth sliding in the damper. In this passive damper, friction force is produced through magnetic repulsive action between two permanent magnetic sources magnetized in the direction normal to the friction surface, and the eddy current damping force is generated because of the motion of the permanent magnetic sources in the vicinity of a conductor. The friction and eddy current damping parts are able to individually produce ideal rectangular and elliptical hysteresis loops, respectively; which, when combined in the proposed device, are able to accomplish a higher input seismic energy dissipation than that only by the friction mechanism. This damper is implemented on a two‐degree‐of‐freedom system to demonstrate its capability in reducing seismic responses of frame building structures. The numerical results show that the seismic performance of the proposed damper is comparable with that of passive magnetorheological damper of the same force capacity. However, the cost of the device is likely to be quite lesser than that of a magnetorheological damper.

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Section: Mathematical Modeling Of a Simple Pemecfdmentioning

confidence: 99%

Section: Eddy Current Dampingmentioning

confidence: 99%

A passive electromagnetic eddy current friction damper (PEMECFD): Theoretical and analytical modeling

Amjadian

Agrawal

2017

Struct. Control Health Monit.

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“…Since the produced eddy currents create a repulsive force that is proportional to the velocity of the conductor, the moving magnet and conductor behave like a viscous damper. Graves et al [5] have derived a mathematical model for eddy current dampers. Burais et al [6] have applied a Rnite element method to the general diffusion equation derived from Maxwell law for the study of the transient and steady state eddy current effects.…”

Section: Introductionmentioning

confidence: 99%

Damping estimation and control of a contactless brake system using an eddy current

et al. 2010

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In this paper, we propose an identification and control method for a control stage with eddy current. The proposed method is that we first obtain the system parameters using an adaptive algorithm and then we design a model-based controller to achieve good performance. The detailed theoretical analysis is given. The experimental results show that the proposed method can guarantee the parameter convergence and improve the control performance.

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“…Sodano et al (2005) have analyzed the suppression of cantilever beam vibrations, where a PM is fixed so that it is perpendicular to the beam motion, and a conducting sheet is attached to the beam tip. Graves et al (2000) have compared the electromagnetic dampers for a given magnetic field and material volume, based on motional and transformer emf designs. Vance et al (2000) investigated the feasibility of the motional and transformer eddy current dampers in aircraft engine applications.…”

Section: Introductionmentioning

confidence: 99%

Permanent magnet configuration in design of an eddy current damper

2008

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This paper discusses the design of an eddy current passive damper using different configurations of permanent magnets. Motional eddy current damping effect is used for the development of a passive damper. Eddy currents are generated in a conductor in a time-varying magnetic field. They are induced either by movement of the conductor in a static field or by changing the strength of the magnetic field, initiating motional and transformer electromotive forces, respectively. The conceived eddy current damper consists of a conductor as an outer tube, and an array of axially magnetized, ring-shaped permanent magnets (PMs), separated by iron pole pieces as a mover. The relative movement of the magnets and the conductor causes the conductor to undergo motional eddy currents. Using this concept, damping characteristics of the new damper is obtained through analytical modeling, and verified by experimental analysis. The optimum PMs' size and configuration are also derived using analytical and finite element analysis, respectively. A damping coefficient as high as 53 kg/s is achievable with the proposed design specifications.

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Theoretical Comparison of Motional and Transformer Emf Device Damping Efficiency

Cited by 49 publications

References 5 publications

A passive electromagnetic eddy current friction damper (PEMECFD): Theoretical and analytical modeling

A passive electromagnetic eddy current friction damper (PEMECFD): Theoretical and analytical modeling

Damping estimation and control of a contactless brake system using an eddy current

Permanent magnet configuration in design of an eddy current damper

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