Magnetostriction and the advantages of using noncontact. Frequency characteristics of magnetostriction in electrical steel related to the structural vibrations. Pdf an overview of magnetostriction, its use and methods to. Manual operation requires careful attention by experienced technicians. For a 2d freestanding thin film, elastic in the linear region, hookes law describes. Magnetostriction is a property of ferromagnetic materials that causes them to change their shape when subjected to a magnetic field. Magnetostriction can be calculated by the magnetostriction coefficient or joules magnetostriction coefficient. This process is performed for loaded transformer or in a noload operating mode by placing vibration accelerometers on the surface of power transformer tank. Reduction of power transformer core noise generation due.
Production of ultrasonics by magnetostriction and piezoelectric methods acoustic. Pdf contribution of magnetostriction to transformer noise. Since magnetostriction is due to the coupling of magnetic and elastic forces, it is of immense technological importance for the conversion of. An overview about these methods can be found in reference 3. He said that this disturbance could be treated as a wave and it would travel at the speed of light. Research on magnetostriction property of silicon steel sheets. The saturation magnetostriction constants lambda100 and lambda111 of yig and fe1xalx x0. Thomas edison used this principle in his first frequency modulated radio power tubes, and it was used for core memory in early mainframe acceptance computers. Us8308874b1 magnetostrictive materials, devices and. A comparison of some available methods is presented in table 1. Magnetostriction is a characteristic of ferromagnetic materials, such as terfenold and galfenol, which causes a change in shape in response to a magnetic field. Magnetostriction can be used to create vibrators, where usually some lever action is used in conjunction with the magnetic deformation to increase the resultant amplitude of vibration.
Using the method described in section 2, the relationship of magnetostriction and magnetic field can be measured. I dont really understand what is the need of giving feedback in the magnetostriction method to produce ultrasonic waves. It pertains to the strain produced along the field direction and is the most commonly used magnetostrictive effect. Modelling of magnetostriction of transformer magnetic core. Magnetostriction can be measured by direct and indirect methods. The magnetostrictive properties of cubic laves phases such as tbfe 2, terfenol d and smfe 2 are summarised. Fast measurement of magnetostriction coefficients for silicon.
The variation of materials magnetization due to the applied magnetic field changes the magnetostrictive strain until reaching its saturation value. Magnetostriction is very small in antiferromagnets. In this paper, a new measurement method using dual heterodyne laser interferometers is proposed to overcome the drawbacks of the old method. Schematic diagram of the tunneling tip method for measuring the magnetostriction and the displacement values itself. The proposed measurement setup and the working principles are explained. Measurement of principal strain and improvement of magnetostriction model figure 3. It is the fractional variation in length as the magnetization raises from 0 to saturation value. For crystalline materials, the use of strain gauges is most common. Deformation of a material, especially a ferromagnetic material, exposed to a magnetic field. In latvian power system, there are three different variants of performing mechanical.
The most sensitive method is the capacitance method, but requires a special sample preparation. Material 100 ppm 111 ppm fe 20 21 ni 46 24 terfenol d 90 1640. Rapidly alternating magnetostriction causes the iron cores of transformers to hum or buzz. Fex alloys based on fega but also feal are presented as materials with a medium magnetostriction, however with the big advantage of a magnetically soft material. The elastic deformation of the molecular structure of ferromagnetic materials like iron, nickel, cobalt and their alloys is called magnetostriction. I am thinking of just winding a single rod over a nickel rod and then connecting then connecting the 2 ends to a battery. An iron rod placed in a magnetic field directed along its length stretches slightly in a weak magnetic field and contracts slightly in a strong magnetic field. Joule magnetostriction is the coupling between the magnetic and elastic regimes in a magnetostrictive material. James maxwell published a paper in1864 describing his theory of how a magnetic disturbance caused by a moving electrical charge, would travel. Therefore, we propose a new method using a magnetostrictionbased electromagnetic acoustic transducer emat to measure the. The most sensitive method is the capacitance method based on the principle of 1920 ultramicrometer and can be applied in a wide temperature range, see fig.
Thermal expansion and magnetostriction, the strain responses of a material to temperature and a magnetic field, especially properties at low temperature, are extremely useful to study electronic and phononic properties, phase transitions, quantum criticality, and other interesting phenomena in cryogenic engineering and materials science. Abstract the cause of magnetostriction is revealed by analyzing this phenomenon in a polydomain. It can be applied to the measurement of magnetostriction on samples of a variety of shapes and geometries including extremely small single crystals that do not permit of ready measurement by other methods. Coupling of the magnetostriction and hall effect in the. Magnetostriction of core laminations is one of the main sources of transformer acoustic noise. Magnetostriction is also used to produce ultrasonic vibrations either as a sound source or as ultrasonic waves in liquids which can act as a cleaning mechanism. Strain gauges are easy to handle but limited in sensitivity. It is denoted by if the length of a ferromagnetic rod is l and after magnetizing it from zeros to saturation level the change in. Therefore, the sensors exhibit considerably longer lifespans and much higher reliability when compared to other technologies, even in harsh working conditions. Mechanically stretching and compressing a magnetized iron rod. Origin of large magnetostriction in fega alloys ruqian wua department of physics and astronomy, university of california, irvine, california 926974575 using the highly precise full potential linearized augmented plane wave method, the phase stability, magnetism, and magnetostriction of fe3ga alloys were investigated. The magnetostriction of grain oriented silicon steel is extremely sensitive to applied compressive stress. Magnetostriction definition of magnetostriction by merriam. When the battery is switched on, the resonant circuit l1c1 sets up an alternating c.
Magnetostriction is the lattice deformation which accompanies magnetization see magnetoelastic phenomena. Magnetization of polydisperse colloidal ferrofluids. Three terminal capacitance technique for magnetostriction. Magnetostriction is one reference no physicist, materials scientist, or geophysicist should be without. Magnetostriction article about magnetostriction by the. It explores recent advances that rely mainly on callens work and emphasizes the influence of temperature, stress, and composition on the joule magnetostriction of soft. New techniques and results in the measurement of magnetostriction. Aug 09, 2014 i dont really understand what is the need of giving feedback in the magnetostriction method to produce ultrasonic waves. A generalized magnetostrictiveforces approach to the. The last chapter is devoted to technical aspects such as experimental methods, technically useful materials e.
Ultrasonics production of ultrasonics by magnetostriction and. Magnetostrictive transducermagnetostriction,working. A measurement system using piezoelectric accelerometers has. Ieee transactions on magnetics, accepted for publication. Nov 10, 2014 for the love of physics walter lewin may 16, 2011 duration. In its second part the paper provides a description of the measurement system for longitudinal magnetostriction and the hall voltage. Jun 08, 2019 magnetostriction can be calculated by the magnetostriction coefficient or joules magnetostriction coefficient. The phenomenon that is the inverse of magnetostrictiona change in the magnetization of a ferromagnetic specimen upon deformationis called the magnetoelastic effect, or sometimes the villari effect. An experiment employing the operatingdeflectionshapes method is used to assess the presented approach under various operating. Due to the magnetostrictive effect, one of the mirrors is shifted by variation in the magnetic field applied to a sample, and the change in the interference pattern is observed. Magnetostriction effect has long been observed and analyzed, and so has its reverse effect that we actually use 2,3. For the love of physics walter lewin may 16, 2011 duration.
When a rod of ferromagnetic material like nickel is magnetized. Since magnetostriction is due to the coupling of magnetic and elastic forces, it is of immense technological importance for the conversion of energy between magnetic and elastic degrees of freedom. It is shown that smfe 2 can be an interesting candidate as a high magnetostrictive material even in the as cast dirty state. Magnetostriction definition is the change in the dimensions of a ferromagnetic body caused by a change in its state of magnetization.
This outstanding reference provides a comprehensive discussion of magnetoelasticity based on three accepted descriptions of magnetostriction. The micromechanical deformation takes place during a change in the magnetisation. Maxwell concluded that light was an electromagnetic wave. A measurement system using piezoelectric accelerometers has been designed and built. More generally, magnetostriction is the phenomenon that the state of strain of a ferromagnetic sample depends on the direction and extent of magnetization. Engineering physics 1 ultrasonic and magnetostriction method. Illustration of measurement device for triaxial laser method top view it is known that from equation 3 the angles of strain and magnetic flux density, and, are equal to each other. An overview of magnetostriction, its use and methods to. For an ideal gas, this method has been demonstrated to be in excellent agreement with a statistical method. Magnetostriction or joule magnetostriction is a consequence of the magnetoelastic coupling. The variation of materials magnetization due to the applied magnetic field changes the magnetostrictive strain until reaching its saturation value, the effect was first identified in 1842 by james joule when observing a sample. The magnetostriction itself, which is one of the subjects of this work, is the phenomenon by which a ferromagnetic sample deforms due to magnetic interactions that can be either within the sample itself spontaneous magnetostriction or caused as a consequence of an external magnetic field forced magnetostriction. This is restricted by the test method des cribed in section 2.
Here we present a simple derivation for an equation relating the gauge factor and the magnetoresistive properties of the sdt devices. The described technique can also be applied to ribbons by rolling or pilingup them into bulk samples. Magnetostriction measurement by using dual heterodyne laser. The production method consist in mixing particles of iron, graphite and sodium chloride with nonpolymerized silicone and rinsing salt particles by water after the matrix polymerization. Novel techniques for characterisation and control of.
Magnetostriction article about magnetostriction by the free. In ferromagnets and ferrimagnets such as iron, nickel, cobalt, gadolinium, and terbium, as well as a number of alloys and ferrites, magnetostriction reaches a significant magnitude relative extension. Magnetostriction magnetostriction is a consequence of the magnetization of the ferromagnetic materials. The magnetostriction model is compatible with various finiteelement structural models and is incorporated into a structural model, updated based on experimental data, representing a clamped laminated structure. When a coil is wounded over a vibrating rod, then e. Three terminal capacitance technique for magnetostriction and. In its second part the paper provides a description of the measurement system for. Us8308874b1 magnetostrictive materials, devices and methods. Fe x ga y al z, where x is of from about 65 at % to about 90 at %, y is of from about 5 at % to about 35 at %, and z is of from about 0 at % to about 30 at %. Single crystal magnetostriction values of fe, ni and terfenol d. With the beckerkersten method the magnetostriction is determined from the stress dependence of the hysteresis loop.
Frequency characteristics of magnetostriction in electrical. Magnetostriction is very small in antiferromagnets, paramagnets, and diamagnets. Longitudinally, it undergoes a very small change in length. Open access related content materials with high magnetostriction. Aug 01, 2011 magnetostriction transducers a magnetostriction transducer is a device that is used to convert mechanical energy into magnetic energy and vice versa. In the case of thin laminated samples, errors due to bending can be eliminated by applying. Magnetostriction, change in the dimensions of a ferromagnetic material, such as iron or nickel, produced by a change in the direction and extent of its magnetization. This paper was presented at an onr sponsored conference on magnetostrictive transducers. During the application of a magnetic field the magnetic domains present in the material rotate to align with the field providing proportional, positive and repeatable expansion in microseconds. The change of length of a ferromagnetic substance when it is magnetized. Yet in time, it can cause the delamination of magnetic core resulting in higher level of vibrations that are measured on the surface of transformer tank during diagnostic tests. Research on magnetostriction property of silicon steel. Pdf an overview of magnetostriction, its use and methods. The magnetic structure of ferromagnetic materials consists of the sum of countless small elementary magnets.
Magnetostriction definition, a change in dimensions exhibited by ferromagnetic materials when subjected to a magnetic field. Magnetostriction is a phenomenon occurring in transformer core in normal operation mode. We exploit magnetostriction in polydisperse ferrofluids in order to generate nonlinear responses, and apply a thermodynamical method to derive the desired nonlinear magnetic susceptibility. Joule magnetostriction is the coupling between the magnetic and.
The mechanical condition of windings and magnetic core of power transformers can be determined by using vibration diagnostics. When the current is passed,magnetic field develops and the rod vibrates and produces ultrasonic waves. You may have noticed the humming sound associated with a transformer or a fluorescent light ballast. Magnetostriction transducers a magnetostriction transducer is a device that is used to convert mechanical energy into magnetic energy and vice versa. Magnetostriction definition of magnetostriction at. It gained wide acceptance because it is a true linear measurement of linear variables. This method of measurement has the following, noteworthy advantages. Such a device can be used as a sensor and also for actuation as the transducer characteristics is very high due to the bidirectional coupling between mechanical and magnetic states of the material. Reduction of power transformer core noise generation due to. Magnetostriction is a proven technology that has been used in a variety of applications over the years.
Pdf the paper provides a description of the magnetostriction effects, and an explanation why it occurs. The circuit diagram of magnetostriction ultrasonic generator is as shown in the figure1. Principle with the aid of two mirrors in a michelson arrangement, light is brought to interference. Presenting some basics about the microscopic behaviour of the ferromagnetic materials can help to understand the magnetostriction phenomenon and to indicate the need for a. Presenting some basics about the microscopic behaviour of the ferromagnetic materials can help to understand the magnetostriction phenomenon and to indicate the need for a measurement method. Magnetostriction measurement by using dual heterodyne.
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