• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.275-278
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• 2002

The performance of Terfenol-D, the commercially available magnetostrictive material, is highly dependent on the prestress, magnetic field intensity and temperature. This paper presents an experimental investigation of the temperature effect on the magnetostriction in Terfenol-D. The effects of both prestress and magnetic field on the magnetostriction are also presented. Experimental results show that both the prestress and magnetic field on the magnetostriction are significant. It is also observed that the displacement decreases slightly to around 40$^{\circ}C$, then increases to 80$^{\circ}C$. It indicates that the displacement decreases due to the reduced magnetization, and increases due to the thermal expansion, as the temperature increases. It means that the reduced magnetization affects more in the displacement change up to 40$^{\circ}C$, and the thermal expansion affects more in the displacement change beyond 40$^{\circ}C$.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.4
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• pp.398-403
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• 2011

Terfenol-D is one of several magnetostrictive materials with property of converting energy into mechanical motion, and vice versa. Magnetostriction is the property that causes certain ferromagnetic materials to change shape in a magnetic field. Terfenol-D is said to produce giant magnetostriction, strain greater than any other commercially available smart material. In this paper, fundamental characteristics analysis of giant magnetostrictive materials(Terfenol-D) has been investigated. The magnetic field analysis is carried out by using finite element method simulation ANSYS. The results show 223N in force and 9.5T in maximum magnetic flux density and 7.56 $10^6A/m$ in maximum magnetic field intensity 1A current. Through the analysis, basic data of Terfenol-D for the application of mechanical system are obtained.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.186-188
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• 1994

Fundamental characteristics of Giant Magnetostrictive Alloy Terfenol-D$(Tb_{0.3}Dy_{0.7}Fe_{1.9\sim1.95})$ were measured by experiments. Magnetostrictions of Terfenol-D samples whose lengths are 15 and 25 mm have been measured under compressive stress from 0 to 14 MPa, when the applied magnetic field was up to 1200 Oe. The relationship between magnetostriction and field is shown graphically in the form of $H-{\lambda}$, curve. For the experiment, solenoid magnet and lever-arm-type stress equipment were designed and fabricated. The magnetostriction is measured by laser displacement measuring system and the stress applied to the sample is measured by load cell.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1069-1070
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.660-663
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• 2003

This paper proposes a systematic approach for an accurate control of the Terfenol-D actuator taking into account hysteresis, modeled by applying the classical Preisach operator with memory curve. A desired input displacement is calculated by using the hysteresis inverter, which is fed into the actuator. Then the PI compensator corrects the error between the commanded and actual displacements. Experiments with the step responses show that the PI controller settles in 70 ms and the hybrid controller in 20 ms. It means that the concurrent application of two control schemes is effective to control the actuator.

• Journal of the Korean Magnetics Society
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• v.4 no.4
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• pp.303-306
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• 1994

Fundamental characteristics of giant magnetostrictive alloy $Terfenol-D(Tb_{0.3}Dy_{0.7}Fe_{1.9~1.95})$ are rreasured and discussed on the application for actuators. The magnetostriction is measured by laser displacement rreasuring system and the applied compressive stress is measured by load cell. Magnetostrictions increased as the applied compressive stresses increased. When the stress is 7 MPa, the magnetostriction is 1000 ppm at 1500 Oe. As the stresses iocreased from 0 to 14 MPa, the magnetic fields for saturating the magnetostriction also increased. The temperature increased during the experiment is $0.3^{\circ}C$, so the thermal expansion is negligible in these experirrents. The feedback or temperature control function should be added for the precise position control actuator.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.751-753
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• 2001

The characteristic of magnetostrictive is to change shape in a magnetic field, TERFENOL-D is said to produce magnetostriction. A magneto strictive actuator need to the magnetic circuit. The most important design consideration is the magnetic circuit. The magnetic circuit consists of the solenoid coil, permanets for bias and shaping of the other parts through which the magnetic field passes. A good magnetic circuit ensures the proper magnetic field in th TERFENOL-D and very uniform magnetic field in all phases of the actuator operating cycle. This paper presents magnetic circuit design and analysis uesing FEM.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.174-181
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• 2004

This paper presents the development of a magnetostrictive microactuator. The structural and functional requirements are as follows: it must be a millimeter structure and must achieve controllable displacement with nanometer resolution. Finite Element Analysis(FEA) is used to determine the structure with the most uniform and highest magnetic flux density along the Terfenol-D rod. The microactuator prototype 1 is designed and made based on the FEA. It is observed that the microactuator show some level of hysteresis and that it produces 25 newton in force and 3 ${\mu}{\textrm}{m}$ in displacement with 1.5 amperes of current, and resolution of 250 nm per 0.1 amperes. To improve the performance of the microactuator prototype 1, microactuator prototype 2 is made again with a permanent magnet (PM). It is observed that the microactuator prototype 2 gene.ates 3.3 ${\mu}{\textrm}{m}$ in displacement with 0.9 amperes of current. It means that the microactuator prototype 2 performs better than the microactuator prototype 1.

• Journal of Magnetics
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• v.13 no.1
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• pp.34-36
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• 2008

For the measurement of the magnetic field distribution with high spatial resolution and high accuracy, the magnetic field sensing probe must be non-magnetic, but the MFM probe and sub-millimeter-meter size Hall probe use a ferromagnetic tip and block, respectively, to increase the sensitivity. To overcome this drawback, we developed a micro-size search coil magnetometer which consists of a single turn search coil, Terfenol-D actuator, scanning system, and control software. To reduce the noise generated by the stray ac magnetic field of the actuator driving coil, we employed an even function $\lambda$-H magnetostriction curve and lock-in technique. Using the developed magnetometer, we were able to measure the magnetic field distribution with a magnetic field resolution of 1 mT and spatial resolution of $0.1mm{\times}0.2mm$ at a coil vibration frequency of 1.8 kHz.

• Journal of Magnetics
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• v.16 no.3
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• pp.211-215
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• 2011

The dynamic magnetostriction characteristics of an Fe-based nanocrystalline FeCuNbSiB alloy are investigated as a function of the dc bias magnetic field. The experimental results show that the piezomagnetic coefficient of FeCuNbSiB is about 2.1 times higher than that of Terfenol-D at the low dc magnetic bias $H_{dc}$ = 46 Oe. Moreover, FeCuNbSiB has a large resonant dynamic strain coefficient at quite low Hdc due to a high mechanical quality factor, which is 3-5 times greater than that of Terfenol-D at the same low $H_{dc}$. Based on such magnetostriction characteristics, we fabricate a new type of transducer with FeCuNbSiB/PZT-8/FeCuNbSiB. Its maximum resonant magnetoelectric voltage coefficient achieves ~10 V/Oe. The ME output power reaches 331.8 ${\mu}W$ at an optimum load resistance of 7 $k{\Omega}$ under 0.4 Oe ac magnetic field, which is 50 times higher than that of the previous ultrasonic-horn-substrate composite transducer and it decreases the size by nearly 86%. The performance indicate that the FeCuNbSiB/PZT-8/FeCuNbSiB transducer is promising for application in highly efficient magnetoelectric energy conversion.