Magnetic damping is a form of damping that occurs when a magnetic field i. Sep 02, 2017 in air damping friction a light blade having considerable area is attached to the moving part to develop a frictional force to opposing the motion by reason of the air they displace. A second topic that has received significant interest is the use of eddy current dampers for. Eddy currents induced by a timevarying magnetic field. Design of a vibration isolation system using eddy current damper partha paul, chetan ingale and bishakh bhattacharya abstract this article aims at modeling, analysis and design of a passivevibration isolation system using a magnetic damper with high efficiency and compactness. Heating conductors by means of eddy currents is called inductive heating. Plug the setup to the wall outlet and set the voltage to its maximum. Eddy currents in the armature of electric motors, or core of transformers, cause joule heating, which lead to losses of energy and overheating. Eddy currents are generated in a conductor in a timevarying magnetic field. In air damping friction a light blade having considerable area is attached to the moving part to develop a frictional force to opposing the motion by reason of the air they displace. Damping mechanisms for precision applications in uhv. Article information, pdf download for novel eddy current damping mechanism for. In fact, eddy current damping is the optimum way of adding extra damping to levitation systems because of its noncontact nature. Magnetic eddy current damping is a viable solution for damping wherehigh temperature extremes are a factor.
Existing treatments of damping of mechanical vibrations by eddy currents consider only two extreme cases. First of all, it is worthy to mention here that all the instrument setting can be adjusted by two means1. Up next eddy currents, magnetic braking and lenzs law duration. To optimize the design of the damping hardware for minimal inertia and maximal damping, it is required to analyze the eddy current drag torque and rotational inertia.
Cda intercorps rotary and linear eddy current dampers offer reliable, repeatable, and linear damping characteristics over a wide operating temperature range. In this physics video lecture in hindi for class 12 we explained eddy current and the cause of this current. Design and experiment of noncontact eddy current damping module. A common physics demonstration device for exploring eddy currents and magnetic damping. Eddy current dampers avior control technologies, inc. Design and damping analysis of a new eddy current damper for. Note that while the damping torque scales quadratically with the. 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.
With this concept, eddy current damping can be used as a form of viscous. Eddy current damping application optimization compositepro chemical 9 jan 17 23. 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. One of most common methods of eliminating eddy currents is use of laminations. This paper describes the design and proof of concept for an active eddy current damper which is integrated into a singleaxis linear motor. Why the eddy current damping more advantageous than air. This technique, which is called eddy current damping, is often employed in galvanometers. Permanent magnet configuration in design of an eddy current.
Study on the eddy current damping of the spin dynamics of. This paper discusses the design of an eddy current passive damper using different configurations of permanent magnets. Eddy current damper, damping, transient analysis, finite element method, aerospace. The first of these is the dissipation of energy though waves being generated by the vessel moving. What relationship, if any, exists between eddy current.
Testing theoretical models of magnetic damping using an air. Eddy current eddy current brake eddy current testing the first link is a general description. Eddy currents and magnetic damping openstax this work is produced by openstaxcnx and licensed under the creative commons attribution license 3. Eddy currents induced in conductors are much stronger as temperatures approach cryogenic. Changing a timevarying magnetic field induces an electromotive force emf in nonmagnetic conductive materials, resulting in an eddy current across the. The results shown below in figure 4 indicate that maximum damping is achieved at a location when.
The measured damping c due to eddy current effect was approximately 6. This current is created due to electromagnetic induction. Magnetic eddy current damping isa better alternative because of its vacuum compatibility and the ability to vary the damping coefficient. The damping rate is defined as the change in reactive torque of the damper, over the change in. 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. If we drive a constant current through the coil, we induce a magnetic flux in the iron. To make it slightly more complex, the rig needs to be torsional rather than linear. Eddy current dampening has been used to suppress ambient vibrations 37. 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.
These eddy currents circulate inside the conductor generating a magnetic field of opposite polarity as the applied magnetic field. Eddy currents and magnetic damping physics lumen learning. When a magnetic field moves through a conductor the movement induces an eddy current in the conductor. 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. 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. 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. Describes the magnitude and the direction of the drag, called magnetic damping produced from eddy currents.
For a static dc field, the copper behaves just like air, not altering the magnetic field. Eddy current damping of a magnet moving through a pipe. Modeling and experiments on eddy current damping caused by a. Eddy currents can produce significant drag, called magnetic. In this video i use lenz law to explain how eddy currents form when a piece of metal passes through a magnetic field. This is often also referred to as electromagnetic braking. 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. The configuration of the designed halbach array ecd is shown in figure 3. Apr 16, 2017 practical demonstration of eddy current damping in induction type energy meter.
Special measures are usually taken to decrease them. Design of a vibration isolation system using eddy current. Design of a vibration isolation system using eddy current damper. Now, divide damping into radiation damping and viscous damping. A harmonic oscillator consisting of a neodymium magnet attached inside a spring is driven through resonance. To understand eddy current we need to understand faradays law of electro magnetic induction. 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. The majority of the research in eddy current damping has taken place in the area of mag netic braking. They are induced either by movement of the conductor in a static field or by changing the strength of the. Eddy current dampers aviors engineering expertise is recognized in the industry as a subject matter expert for eddy current dampers and controlled deployment systems. Eddy current damping application optimization magnetic.
Short video made by aaron macraighne, matt barr and fiona meade covering eddy currents, magnetic braking and lenzs law. 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. It is shown by vinti in reference 4 \ the purpose of this paper is to derive and present expressions for the average torques due to induced eddy currents acting on a satellite and to study. Move the aluminum saw through the gap between magnets and feel the damping force. Eddy current damping in structures semantic scholar. Eddy currents, magnetic braking and lenzs law helpful conceptual video. Keywords passive and active vibration isolation, eddy current damping, electromagnetic vibration isolator, direct output feedback control date received. Damping ratio from eddy current breaking physics forums. Here is a link to a lab exercise that seems to me to explain the role of the eddy current damping in a torsion pendulum quite well. There are lots of sources of info on eddy currents.
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 currents circulate in the conductive material and are dissipated, causing a repulsive force between the magnet and the conductor. 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. Study on the eddy current damping of the spin dynamics of spatial debris from the ariane launcher due to the remaining fuel in the tanks, eddy current torque, air drag for trajectories having altitude below 500 km. Nov 14, 2008 this paper discusses the design of an eddy current passive damper using different configurations of permanent magnets. Eddy currents, magnetic braking and lenzs law youtube. Concept and model of eddy current damper for vibration. Due to these eddy currents a force exists between them and the field. Jan 20, 2014 hello all, i have been asked to design and build a rig that will introduce the concept of a mass spring damper system to mechanical engineers in their early years of university. Precision motion control with active eddy current damper. Nov 28, 2017 to understand eddy current we need to understand faradays law of electro magnetic induction. The damping force from the eddy currents which are generated by a conductor plate cutting through magnetic lines of forces can help.
Motional eddy current damping effect is used for the development of a passive damper. The fea model was configured with the same parameters as in the test configuration and analysed. Hello all, i have been asked to design and build a rig that will introduce the concept of a mass spring damper system to mechanical engineers in their early years of university. Although developments on active eddy current damper are well documented, none has been implemented in a linear motor. These rugged devices are offered in a range of sizes and damping rates. The eddy current dampers ecds are complemented with single or multiple stages of high reliability gearing. They are induced either by movement of the conductor in a static field or by changing the strength of the magnetic. Eddy current brakes use the drag force created by eddy currents as a brake to slow or stop moving objects.
Novel eddy current damping mechanism for passive magnetic. Although the studies related to eddy currents go back. Sodano and jaesung bae abstractwhen a conductive material is subjected to a timevarying magnetic flux, eddy currents are generated in the conductor. The principle of eddy current damping is shown in figure 3. The first is that of a homogeneous specimen, where the currents are all on the scale of the specimen dimensions. Us8203316b2 eddy current torsional damper for generator. Design and damping analysis of a new eddy current damper. Since there is no contact with a brake shoe or drum, there is no mechanical wear.
Actuators free fulltext effect of electromagnetic damping on. 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. The electromagnetic analysis and design of a new permanent. 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. Pdf eddy current damping in structures researchgate. Eddy current damping harvard natural sciences lecture. Effects of magnetically induced eddycurrent torques on spin. Magnetic damping setup including al saw, al and cu rings setup. Autoplay when autoplay is enabled, a suggested video will automatically play next.
If motional emf can cause a current loop in the conductor, we refer to that current as an eddy current. What is the difference between damping, drag, drag caused by current, and drag caused by waves. The dc flux density across the air gap in our example is about 0. Eddy current damping is the optimum method of adding extra damping to levitation systems because of its noncontact nature. 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. Moreover, eddy current damping does not affect the controller algorithm or the complexity of the system and does not degrade over time 15. First lets us agree that drag and damping are considered the same. Testing theoretical models of magnetic damping using an air track ana vidaurre.
1079 1203 395 614 216 375 506 1284 60 373 764 820 1355 67 94 1530 1583 1047 205 481 779 218 1226 1101 1077 835 418 11 739 258 348 175 275 1248 971 281