Application of an eddy currenttuned mass damper to. Magnetic eddy current damping is a viable solution for damping wherehigh temperature extremes are a factor. The flow of electrons in the conductor immediately creates an. Due to these eddy currents a force exists between them and the field. To better understand the concept of eddy current, let us take an example. Noncontact vibration control system employing an active. Nov 28, 2017 to understand eddy current we need to understand faradays law of electro magnetic induction. Newest dampingfactor questions electrical engineering. They can be induced within nearby stationary conductors by a timevarying magnetic field created by an. Design and damping analysis of a new eddy current damper for aerospace applications latin american journal of solids and structures 2016 19972011 noncontact, nonleakage and easy implementation, become a candidate to suppress vibrations of a. The measured damping c due to eddy current effect was approximately 6. Plug the setup to the wall outlet and set the voltage to its maximum. Move the aluminum saw through the gap between magnets and feel the damping force. Nov 14, 2008 this paper discusses the design of an eddy current passive damper using different configurations of permanent magnets.
A passive eddy current damper for vibration suppression of. This information will be used by another team to create an eddy current. Eddy current dampers avior control technologies, inc. These currents set up their own magnetic fields, which through lenzs law oppose the change that caused them. Eddy current damping harvard natural sciences lecture. Eddy currents are induced when a nonmagnetic, conductive material is moving as the result of being subjected to a magnetic field, or if it is placed in a timevarying magnetic field. The electromagnetic analysis and design of a new permanent magnetic eddy current damper xie hu, ma shuyuan, li wenbin abstractthe thesis suggests the design of a passive permanent magnetic eddy current damper.
Jan 21, 2010 eddy currents are induced when a nonmagnetic, conductive material is moving as the result of being subjected to a magnetic field, or if it is placed in a timevarying magnetic field. Modeling and experiments on eddy current damping caused by. Wright for their lectures that broadened my knowledge. Us8203316b2 eddy current torsional damper for generator. In this various types of eddy current damping mechanisms and the future of eddy currents with some potential uses have been seen when a nonmagnetic conductive material experiences a timevarying magnetic field, eddy current continuous change in flux that induces an electromotive force e. This paper discusses the design of an eddy current passive damper using different configurations of permanent magnets. Design and damping analysis of a new eddy current damper. Experimental tuned mass damper based on eddy currents. Khatibi 2 1 department of mechanical engineering, islamic azad university of. This eddy current loss formula or equation can be used in all electrical machines like transformers, ac and dc motors to calculate the.
Design and damping analysis of a new eddy current damper for aerospace applications 1 introduction the rapid development of aerospace technologies has led to a variety of applications like high resolution remote sensing, observation camera etc. Experiment s eddy current damping aim this is a short demonstration experiment in which the observations are qualitative, to introduce you to using liquid nitrogen and to the ideas of eddy currents. The damping force from the eddy currents which are generated by a conductor plate cutting through magnetic lines of forces can help. In this work we studied the phenomenon of eddy current braking. Consider the apparatus shown in figure \\pageindex1\, which swings a pendulum bob between the poles of a strong magnet. This energy here comes at the cost of kinetic energy of the moving plate and hence the metallic plate is slow down. Review of passive electromagnetic devices for vibration damping. Passive eddy current damping as a means of vibration control in cryogenic turbomachinery, nasa technical paper number nasatp2562, access no. The results shown below in figure 4 indicate that maximum damping is achieved at a location when. Permanent magnet configuration in design of an eddy. Pdf eddy current braking and simulation of a magnet. A theoretical model for the eddy current damper ecd was.
A novel current force model considering higherorder harmonics is. However, an eddy current brake cannot provide a holding torque and so may be used in combination with mechanical brakes, for example, on overhead cranes. Design and damping analysis of a new eddy current damper for. They are induced either by movement of the conductor in a static field or by changing the strength of the. The fea model was configured with the same parameters as in the test configuration and analysed. Analysis of force harmonics and eddy current damping for 2. Magnetic eddy current damping isa better alternative because of its vacuum compatibility and the ability to vary the damping coefficient. Pdf modeling and experiments on eddy current damping caused. These currents circulate in the conductive material and are dissipated, causing a repulsive force between the magnet and the conductor. Design of a vibration isolation system using eddy current damper. Design and modeling of a magnetic shock absorber based on eddy current damping effect.
The relative motion of these magnets induces eddy currents in both the sensor and the annulus, with such currents being proportional to the materials conductivity. The magnetic flux produced by the eddy currents opposes the flux from the permanent magnet and decreases. Vibration control of cantilever beam based on eddy current. Internoise 2014 page 1 of 14 investigations of eddy current vibration damping karel 2ruber1. Since the resistive force induced by eddy currents is proportional to the relative velocity, the conductor and the magnet can be allowed to func tion as a form of.
Furthermore, the relative severity of a discontinuity may be indicated, and a rejection level may be set with respect to the magnitude of. Permanent magnet configuration in design of an eddy current. Eddy currents also called foucaults currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to faradays law of induction. Modeling and experiments on eddy current damping caused by a. Eddy current damper, damping, transient analysis, finite element method, aerospace. Solution for 2 oscillations m 2 and x 1 x 2 1005 20 the actual damping coefficien t is c c x 251. Novel eddy current damping mechanism for passive magnetic bearings, journal of vibration and control 1411. I have read in many texts that the closed loop system damping factor can be approximated as. May 15, 2017 we have seen, in the above example, that when a conductor is moved in a magnetic field a motional emf is generated. This is the basic concept behind the electromagnetic damping. The decreased amplitude of oscillations by the interaction of magnetic fields.
Eddy currents can produce significant drag, called magnetic damping, on the motion involved. The interaction of the two magnetic fields causes a force that resists the change in magnetic flux. Vibration control of cantilever beam based on eddy current damping rahul sharma, hartaj, harinder pal and s. Experimental tuned mass damper based on eddy currents damping effect and adjustable stiffness. The developments and unparalleled performance reflect a dedication to innovation and continuous improvement in the development and implementation of high reliability, space. Eddy current dampers aviors engineering expertise is recognized in the industry as a subject matter expert for eddy current dampers and controlled deployment systems. Full text of eddy current damping in flat and cylindrical.
Learn how to quantitatively model a real harmonic oscillator 2. In real life, eddy currents can be used in transportation systems like monorails or innercity rapid transit cars on rails to generate a stopping force. Due to lenzs law this force is always in opposition to the force causing rotation of the conducting, material, thus, it provides the necessary damping. Design of a vibration isolation system using eddy current. The principle of eddy current damping is shown in figure 3. The flow of electrons in the conductor immediately creates an opposing magnetic field which results in damping of the magnet and produces heat inside the conductor similar to heat buildup inside of a power cord during use. The electromagnetic analysis and design of a new permanent. Lee and park6 designed an optimal controller for an eddy current brake to minimize the stopping time of a disc in an automobile. In the case of a vertical card magnetic compass, flux from the oscillating permanent magnet produces eddy currents in a damping disk or cup.
Eddy current damping in structures article pdf available in the shock and vibration digest 366. Non contact eddy current dampers for control systems. What is an eddy current and how do you explain it with a. With this concept, eddy current damping can be used as a form of viscous damping. Design and modeling of a magnetic shock absorber based on. Eddy currents and magnetic damping openstax this work is produced by openstaxcnx and licensed under the creative commons attribution license 3. As discussed in motional emf, motional emf is induced when a conductor moves in a magnetic field or when a magnetic field moves relative to a conductor. These eddy currents circulate inside the con ductor generating a magnetic field of opposite polarity as the applied magnetic field. Eddy currents are generated in a conductor in a timevarying magnetic field. In the present study, the electromagnetic theory is applied to estimate the damping feature of the eddy current within the ectmd system. Modeling and experiments on eddy current damping caused by a permanent magnet in a conductive tube article pdf available in journal of mechanical science and technology 2311. The nonconservative forces that include the internal damping of the beam and the eddy current damping force can be written as the damping matrix defined by 24 c.
Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. Abstractthis paper presents the analysis of force harmonics and eddy current damping for 2 dof moving magnet linear motor mmlm, which is utilized in magnetically levitated maglev positioning systems. Eddy current damping application optimization magnetic. Robert randall3 1,2,3 school of mechanical and manufacturing engineering, the university of nsw unsw, sydney, australia abstract eddy currents are generated in electrically conductive materials such as copper in response to a moving. In addition to the applications of eddy currents, zuo et al 17 introduced a new type of electromagnetic damper with increased energy density. Eddy currents can produce significant drag, called magnetic damping, on the motion involved consider the apparatus shown in figure 1, which. Csma 2015, 12 colloque national en calcul des structures, csma, may 2015, giens, france. Magnetic damping is a form of damping that occurs when a magnetic field i.
They are induced either by movement of the conductor in a static field or by changing the strength of the magnetic. It worked well in the highspeed range because the damping force is directly proportional to the angular speed. Dynamic behavior of torsional eddy current dampers. Pdf eddy current damping in structures semantic scholar.
Eddy current damping lenzs law induced currents faradays law what it shows. Eddy currents and magnetic damping as discussed in motional emf, motional emf is induced when a conductor moves in a magnetic field or when a magnetic field moves relative to a conductor. Classification, absolute and secondary instruments, indicating instruments, control, balancing and damping, constructional details, characteristics, errors in measurement, ammeters, voltmeters. Because of such eddy current in the metal plates, thermal energy is produced in the plate. Machining tests were carried out on thinoored compliant parts with and without magnetic damping. In this paper we detail much of the work that has been performed in the area of eddy current damping and we detail many more advantages of these types of damping systems.
Development of novel eddy current dampers for the suppression of structural vibrations henry a. The support from the california department of transportation, the national science foundation, the electric power research institute, and pacific. Damping mechanisms for precision applications in uhv environment. So when an alternating magnetic field is applied to a magnetic material, an emf is induced in the material itself according to faradays law of electro m. Various studies followed these pioneers that discuss braking and damping effects of eddy currents 2124. The most widely researched and welldeveloped area of eddy current damping systems falls in the category of magnetic braking. Describes the magnitude and the direction of the drag, called magnetic damping produced from eddy currents. We have seen, in the above example, that when a conductor is moved in a magnetic field a motional emf is generated.
What relationship, if any, exists between eddy current. When a magnet falls through a metal pipe, such as copper or aluminum tube, it creates eddy current on the walls. Stefania lo feudo, anissa allani, gwendal cumunel, pierre argoul, domenico bruno. However, unlike friction brakes, in which the drag force that stops the moving object is provided by friction between two surfaces pressed together, the drag force in an eddy current brake is an electromagnetic. These currents are called eddy currents, and in the rotating system, the emf produced generates a force to the left that opposes the motion of the conductor itself. An eddy current brake, also known as an induction brake, electric brake or electric retarder, is a device used to slow or stop a moving object by dissipating its kinetic energy as heat. Dec 20, 2005 the nonconservative forces that include the internal damping of the beam and the eddy current damping force can be written as the damping matrix defined by 24 c. Concept and model of eddy current damper for vibration. In this lab, youll explore the oscillations of a massspring system, with and without damping. Sensitivity of the design parameters article pdf available in ieee transactions on magnetics 437. Since there is no contact with a brake shoe or drum, there is no mechanical wear. Sep 28, 2000 masons expression indicates that the microeddy current damping depends on d 2, but the general opinion is that the domain walls move during a stress cycle and thus d varies with the applied stress. Closed loop control of filter inductor current and dclink voltage, pwm measures dclink voltage, minimum two filter inductor currents and two line voltages.
If motional emf can cause a current loop in the conductor, we refer to that current as an eddy current. Eddy current brake design for operation with extreme back. What relationship, if any, exists between eddy current damping and velocity in a simple aluminum track system. Active damping of oscillations in lcfilter for line. Development of a new family of normalized modulus reduction. Impact testing was performed on undamped and magnetically damped cantilever beams to quantify the amount of damping introduced by the magnet con guration being used. A sheet of aluminum falls slowly between the poles of a magnet because induced currents in the sheet set up magnetic fields which oppose the motion. Magnetic damping setup including al saw, al and cu rings setup. When a conductive material is subjected to a timevarying magnetic flux, eddy currents are generated in the conductor. However, due to the limited capacity of the shuttle bay, progress towards the. When a magnetic field moves through a conductor the movement induces an eddy current in the conductor. Eddy current damping application optimization compositepro chemical 9 jan 17 23. Eddy current brakes use the drag force created by eddy currents as a brake to slow or stop moving objects. A generator rotor torsional damper system includes a prime mover for generating rotational force, a generator stator, a generator rotor rotatably supported relative to the generator stator and configured to receive a rotational force input from the prime mover, a flywheel rotationally supported relative to the generator rotor by bearings, and an eddy current coupling operably connected between.
Learn how damping affects simple harmonic motion b. Thus the word itself means current having no definite circular loop. Eddy current is defined as the induced current on the surface of conductor in little loops or eddies due to changing magnetic flux. Motional eddy current damping effect is used for the development of a passive damper. Sodano abstract the optical power of satellites such as the hubble telescope is directly related to the size of the primary mirror. Pdf dynamic behavior of torsional eddycurrent dampers. We hope to learn the effect of stator spacing, magnet size and shape, number of magnets, magnet radius, and phase angle have on braking force. Non contact eddy current dampers for control systems i. Pdf design and damping analysis of a new eddy current.
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