Development of a New Passive-Active Magnetic Damper for Vibration Suppression

2005 ◽  
Vol 128 (3) ◽  
pp. 318-327 ◽  
Author(s):  
Henry A. Sodano ◽  
Daniel J. Inman ◽  
W. Keith Belvin
Keyword(s):  
Magnetic Field ◽  
Control System ◽  
Eddy Currents ◽  
Vibration Suppression ◽  
Internal Resistance ◽  
Viscous Force ◽  
Damping Force ◽  
Conductive Material ◽  
Damping Effect ◽  
Active Portion

Magnetic fields can be used to apply damping to a vibrating structure. Dampers of this type function through the eddy currents that are generated in a conductive material experiencing a time-changing magnetic field. The density of these currents is directly related to the velocity of the change in magnetic field. However, following the generation of these currents, the internal resistance of the conductor causes them to dissipate into heat. Because a portion of the moving conductor’s kinetic energy is used to generate the eddy currents, which are then dissipated, a damping effect occurs. This damping force can be described as a viscous force due to the dependence on the velocity of the conductor. In a previous study, a permanent magnet was fixed in a location such that the poling axis was perpendicular to the beam’s motion and the radial magnetic flux was used to passively suppress the beam’s vibration. Using this passive damping concept and the idea that the damping force is directly related to the velocity of the conductor, a new passive-active damping mechanism will be created. This new damper will function by allowing the position of the magnet to change relative to the beam and thus allow the net velocity between the two to be maximized and thus the damping force significantly increased. Using this concept, a model of both the passive and active portion of the system will be developed, allowing the beams response to be simulated. To verify the accuracy of this model, experiments will be performed that demonstrate both the accuracy of the model and the effectiveness of this passive-active control system for use in suppressing the transverse vibration of a structure.

Modeling of a New Active Eddy Current Vibration Control System

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Henry A. Sodano ◽  
Daniel J. Inman
Keyword(s):  
Magnetic Field ◽  
Vibration Control ◽  
Electric Fields ◽  
Eddy Current ◽  
Eddy Currents ◽  
Vibration Suppression ◽  
Frequency Doubling ◽  
Damping Force ◽  
Theoretical Derivation ◽  
Eddy Current Damping

There exist many methods of adding damping to a vibrating structure; however, eddy current damping is one of few that can function without ever coming into contact with that structure. This magnetic damping scheme functions due to the eddy currents that are generated in a conductive material when it is subjected to a time changing magnetic field. Due to the circulation of these currents, a magnetic field is generated, which interacts with the applied field resulting in a force. In this manuscript, an active damper will be theoretically developed that functions by dynamically modifying the current flowing through a coil, thus generating a time-varying magnetic field. By actively controlling the strength of the field around the conductor, the induced eddy currents and the resulting damping force can be controlled. This actuation method is easy to apply and allows significant magnitudes of forces to be applied without ever coming into contact with the structure. Therefore, vibration control can be applied without inducing mass loading or added stiffness, which are downfalls of other methods. This manuscript will provide a theoretical derivation of the equations defining the electric fields generated and the dynamic forces induced in the structure. This derivation will show that when eddy currents are generated due to a variation in the strength of the magnetic source, the resulting force occurs at twice the frequency of the applied current. This frequency doubling effect will be experimentally verified. Furthermore, a feedback controller will be designed to account for the frequency doubling effect and a simulation performed to show that significant vibration suppression can be achieved with this technique.

Analysis and Modeling of Eddy Current Damping for Short-Stroke DC Linear Motor

2013 ◽  
Vol 416-417 ◽  
pp. 300-304
Author(s):  
Dong Hua Pan ◽  
Jia Xi Liu ◽  
Feng Jing Shen ◽  
Li Yi Li ◽  
Ming Na Ma
Keyword(s):  
Magnetic Field ◽  
Eddy Current ◽  
Eddy Currents ◽  
Linear Motor ◽  
Force Model ◽  
Equivalent Resistance ◽  
Damping Force ◽  
Conductive Material ◽  
Charge Model ◽  
Eddy Current Damping

Eddy currents induced in a conductor in a changing magnetic field produce a damping force proportional to the heat generated in the conductive material. In this paper, the damping force of short-stroke DC Linear Motor (DCLM) is researched, and then model of damping force is established. In the preliminary work, the analytical expression of magnetic field distribution is obtained by the charge model, so the eddy current inducted in the conductor is calculated. Then the damping force is obtained after the equivalent resistance and inductance of conductors are calculated. The formula of damping force is obtained to optimize damping structure of short-stroke DCLM. The accuracy of damping force model is proved by the experiment.

Modeling of Eddy Current Damper Composed of Spherical Magnet and Conducting Shell

2006 ◽  
Author(s):  
Yoshihisa Takayama ◽  
Atsuo Sueoka ◽  
Takahiro Kondou
Keyword(s):  
Magnetic Field ◽  
Eddy Current ◽  
Magnetic Force ◽  
Eddy Currents ◽  
Reaction Force ◽  
Damping Force ◽  
Magnetic Damping ◽  
Conducting Plate ◽  
Direction Of Movement ◽  
Eddy Current Damper

If a conducting plate moves through a nonuniform magnetic field, eddy currents are induced in the conducting plate. The eddy currents produce a magnetic force of drag, known as Fleming's left-hand rule. This rule means that a magnetic field perpendicular to the direction of movement generates a magnetic damping force. We have fabricated the eddy current damper composed of the spherical magnet and the conducting shell. The spherical magnet produces the axisymmetric magnetic field, and the shape of the conducting shell appears to combine a semispherical shell conductor and a cylinder conductor. When the eddy current damper works, the conducting shell is fixed in space, and the spherical magnet moves under the conducting shell. In this case, since there are magnetic flux densities perpendicular to the direction of movement, eddy currents flow inside the conducting shell, and then a magnetic force is produced. The reaction force of this magnetic force acts on the spherical magnet. In our study, eddy current dampers composed of a magnet and a conducting plate have been modeled using infinitesimal loop coils. As a result, magnetic damping forces are obtained. Our modeling has three merits as follows: the equation of a magnetic damping force is simple in the equation, we can use the static magnetic field obtained using FEM, the Biot-Savart law or experiments and the equation automatically satisfies boundary conditions using infinitesimal loop coils. In this study, we explain simply the principle of this method, and model an eddy current damper composed of a spherical magnet and a conducting shell. The analytical results of the modeling agree well with the experimental results.

Precision Motion Control with Active Eddy Current Damper

2010 ◽  
Vol 447-448 ◽  
pp. 493-497
Author(s):  
Chek Sing Teo ◽  
Chea Jack Ong ◽  
C.J. Ho ◽  
S. Huang ◽  
K.K. Tan
Keyword(s):  
Eddy Current ◽  
Eddy Currents ◽  
Vibration Suppression ◽  
Linear Motor ◽  
Precision Motion Control ◽  
Damping Effect ◽  
Eddy Current Damper ◽  
Damper Design ◽  
Precision Motion ◽  
Conducting Sheet

This paper describes the design and proof of concept for an active eddy current damper which is integrated into a single-axis linear motor. Although developments on active eddy current damper are well documented, none has been implemented in a linear motor. The advantage of such a system is two-fold. Firstly, the relative motion between the magnets and the conducting sheet produces eddy currents resulting in an electromagnetic force opposing the direction of motion; which can be utilized to suppress vibrations. Secondly, it is possible to enhance the damping effect of the system; Due to environmental noise, it is normally not possible to increase the D coefficient in a PID controller as much as desirable. The damper is thus able to supplement this damping effect to improve settling time. Here, we will present the damper design as well as the preliminary experiment results for both vibration suppression and motion damping.

Microscale Flanging Using Quasi-Static and Electromagnetic Forming Processes

2008 ◽  
Author(s):  
Reid VanBenthysen ◽  
Jonathan Michaud ◽  
Peter DiSalvo ◽  
Brad L. Kinsey ◽  
Michael Blakely ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Deformation Mechanism ◽  
Material Properties ◽  
Eddy Currents ◽  
Capacitor Bank ◽  
Elastic Recovery ◽  
Past Research ◽  
Electromagnetic Forming ◽  
Stored Energy ◽  
Conductive Material

Past research has shown that scatter in material properties and springback (i.e., the elastic recovery of material after the tooling is extracted) increase as components are miniaturized to the microscale. At the macroscale, electromagnetic forming (EMF) has been shown to completely eliminate or at least decrease springback by varying the deformation mechanism. In EMF, a capacitor bank is charged and then quickly dissipated into a specially designed magnetic coil. A transient magnetic field is produced which induces eddy currents in the workpiece, and any other conductive material nearby. The magnetic fields in the coil and the workpiece are repulsive; thus, the workpiece is launched at a high velocity away from the coil. EMF at the macroscale requires a significant amount of stored energy. However at the microscale, EMF may be a viable process due to the reduced energy and force requirements and thus is being investigated in this work.

Anti-resonance Vibration Suppression Control in Full-closed Control System

2019 ◽  
Vol 139 (10) ◽  
pp. 847-853
Author(s):  
Yasufumi Yoshiura ◽  
Yusuke Asai ◽  
Yasuhiko Kaku
Keyword(s):  
Control System ◽  
Vibration Suppression ◽  
Resonance Vibration

Concurrent Vibration Suppression and Energy Harvesting Using Ferrofluids: An Experimental Investigation

2014 ◽  
Author(s):  
Saad F. Alazemi ◽  
Amin Bibo ◽  
Mohammed F. Daqaq
Keyword(s):  
Magnetic Field ◽  
Power Generation ◽  
Energy Harvesting ◽  
Vibration Suppression ◽  
Design Parameters ◽  
Structural Vibrations ◽  
Rectangular Container ◽  
Fluid Damper ◽  
Magnetized Ferrofluid ◽  
Experimental Response

This paper presents an experimental study which examines the design parameters affecting the performance characteristics of a Tuned Magnetic Fluid Damper (TMFD) device designed to concurrently mitigate structural vibrations and harvest vibratory energy. The device which is mounted on a vibrating structure, consists of a rectangular container carrying a magnetized ferrofluid and a pick-up coil wound around the container to enable energy harvesting. Experiments are performed to investigate the three-way interaction between the vibrations of the structure, the sloshing of the fluid, and the harvesting circuit dynamics. In particular, the tuning and optimization is examined for several design parameters including magnetic field spatial distribution and intensity, winding direction, winding location, winding density, and ferrofluid height inside the tank. The experimental response of the device is compared against the conventional TMFD at different excitation levels and frequencies. Results demonstrating the influence of the significant parameters on the relative performance are presented and discussed in terms of vibration suppression and power generation capabilities.

THE ROTATIONAL EFFECT OF MAGNETIC PARTICLES ON CELLULAR APOPTOSIS BASED ON FOUR ELECTROMAGNET FEEDBACK CONTROL SYSTEM

2021 ◽  
pp. 2150045
Author(s):  
Jia Ji Lee ◽  
Chang Hong Pua ◽  
Misni Misran ◽  
Poh Foong Lee
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Control System ◽  
Feedback Control ◽  
Cell Apoptosis ◽  
Magnetic Particles ◽  
Drug Carriers ◽  
Feedback Control System ◽  
Rotational Effect ◽  
Dynamic Magnetic Field

Objectives: Magnetic drug targeting offers the latest popular alternative option to deliver magnetic drug carriers into targeting region body parts through manipulation of an external magnetic field. However, the effectiveness of using an electromagnetic field to manipulate and directing magnetic particles is yet to be established. Methods: In this paper, a homemade cost-effective electromagnet system was built for the purpose of studying the control and directing the magnetic drug carriers. The electromagnet system was built with four electromagnetic sources and tested the capability in directing the particles’ movement in different geometry patterns. Besides that, the creation of the self-rotation of individual magnetic particle clusters was achieved by using fast switching between magnetic fields. This self-rotation allows the possibility of cell apoptosis study to carry out. The system was constructed with four electromagnets integrated with a feedback control system and built to manipulate a droplet of commercially available iron (II, III) oxide nanoparticles to steer the magnetic droplet along different arbitrary trajectories (square, circle, triangle, slanted line) in 2-dimensional. Results: A dynamic magnetic field of 25 Hz was induced for magnetic nanoparticles rotational effect to observe the cell apoptosis. A profound outcome shows that the declining cell viability of the cell lines by 40% and the morphology of shrinking cells after the exposure of the dynamic magnetic field. Conclusion: The outcome from the pilot study gives an idea on the laboratory setup serves as a fundamental model for studying the electromagnetic field strength in applying mechanical force to target and to rotate for apoptosis on cancer cell line study.

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