• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.276-279
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• 1997

When a magnetostrictive material is exposed to a magnetic field, its geometry changes due to a magnetostrictive effect. The magnetostriction is analogous to the piezoeletricity. The displacement of the magnetostrictive material is proportional to the applied current while that of the piezoelectric material is proportional to the voltage. A magnetostrictive material generates large displacement and higher compressive force compared with a piezoeletric material. These advantages provide a good performance of a vibration isolation of a platform. In this work, it is applied to a driving actuator for vibration isolation of a platform. The properties of a magnetostrictive material are investigated in terms of hysteresis and displacement vs. applied current for a various preload. Modeling of the displacement of the vibration isolating actuator is performed as it behaves as a flow source. A sliding mode controller is designed to demonstrate the ability of the magnetostrictive actuator to reduce the vibration at the platform. The effectiveness of the proposed scheme is demonstrated through experimental works. The experimental results of the vibration of the platform axe presented in terms of time response and frequency response.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.370.2-370
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• 2002

Magnetostrictive materials are used low-frequency sonar transmitter instead of piezoelectric materials. But it is difficult to analyze due to the nonlinearity and hysteresis of magnetostrictive materials. This paper deals with the program development based on finite element method to model the magnetostrictive tonpilz transducers and to analyze their acoustic characteristics. (omitted)

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.76-80
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• 2011

This paper proposes a method to calculate magnetostrictive forces, displacement, and vibration modes of a large-scale Brushless DC(BLDC) motor by using a magneto-mechanically strong coupling formulation. The force is calculated using the energy method with magnetostrictive stress tensor. The mechanical vibration modes are also analyzed by using the principle of Hamilton and the calculated magneto-elastic forces acting on the surfaces of the stator. To verify the algorithm, 3 MW BLDC motor is simulated, and the forces, displacements, and vibration modes are calculated. The result shows that the mechanically stressed core has more deformation or displacements than those of the normal condition.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.3
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• pp.24-32
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• 2007

In this research, using Terfenol-D actuator composed of magnetostrictive material as shaker and controller, active vibration control theory was applied and verified by experiments. PPF(positive Position Feedback) algorithm which is effective for the control of low frequency vibration was used for the control of a structure. Responses of inputs due to various design variable used for the PPF filter were observed. To investigate the characteristics of magnetostrictive materials, actuator responses were measured for known inputs and satisfactory results were obtained to reduce the vibration level after applying the control input for the actuator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.705-710
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• 2002

Magnetostrictive materials are used low frequency sonar transmitter instead of piezoelectric materials. But it is difficult to analyze due to the nonlinearity and hysteresis of magnetostrictive materials. This paper deals with the program development for the finite element modeling of magnetostrictive tonpilz transducers and for analyzing their acoustic characteristics. To take into account the nonlinearity of magnetostrictive materials, the magnetic field calculation is separated form the displacement calculation, and a curve fitting is adopted for the nonlinear behavior of the magnetic and mechanical strain fields. At first, the magnetic field is obtained by using a commercial FEM software and the displacement of the transducer is calculated by plugging the obtained magnetic field into forcing term. To verity the accuracy of the developed program, a comparison is made with a commercial code, ATILA.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.4 s.121
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• pp.356-362
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• 2007

Magnetostrictive materials have been used for linear actuators due to its large strain, large force output with moderate frequency band in the presence of magnetic field. However their performance analysis is difficult because of nonlinear material behaviors in terms of coupled strain-magnetic field dependence, nonlinear permeability, pre-stress dependence and hysteresis. This paper presents a finite element analysis technique for magnetostrictive linear actuator. To deal with coupled problems and nonlinear behaviors, a simple finite element approach is proposed, which is based on separate magnetic field calculation and displacement simulation. The finite element formulation and an in-house program development are illustrated, and a simulation model is made for a magnetostrictive linear actuator. The fabrication and performance test of the linear actuator are explained, and the performance comparison with simulation result is shown. Since this approach is simple, it can be applied for analyzing magnetostrictive underwater projectors and ultrasonic transducers.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.3
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• pp.227-233
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• 2011

The ultrasonic guided wave phased array using magnetostrictive patch transducers is proposed. The magnetostrictive transducer has received much attention because it is cost-effective and capable to generate ultrasonic waves with a simple configuration. However, it has not been used for ultrasonic guided wave phased array applications until now. In this paper, we propose a magnetostrictive transducer based phased array system consisting of a multi-channel function generator, power amplifiers and Lamb wave magnetostrictive transducers. To check the performance of the ultrasonic guided wave phased array, several Lamb wave focusing experiments were carried out in an aluminum plate. The results demonstrated the capability of the developed array to focus the Lamb waves at specific target points.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1159-1164
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• 2006

Torsional vibration is an important vibration mode when shafts, cylinders and pipes are considered. However, the modal testing of torsional vibrations is not an easy job to carry out because of the lack of proper transducers. This work presents a new torsional vibration transducer based on the magnetostrictive principle and its application to torsional modal testing. The transducer is so designed as to generate/measure only torsional vibrations excluding other vibration modes such as longitudinal and bending vibrations. The transducer is composed of ferromagnetic patches bonded to a test structure, permanent magnets, and a solenoid. Though patches and magnets are bonded to a structure, torsional vibrations are generated and measured wirelessly by a solenoid encircling a test structure. The proposed transducer works even at considerably high frequencies, say, tens of kilohertz. Furthermore, the transducer can be manufactured at a low price. To check the performance of the proposed method, the torsional modal testing on a hollow aluminum shaft was conducted. The results, such as eigenfrequencies, obtained by the proposed transducer agreed favorably with theoretical results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.8 s.113
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• pp.879-885
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• 2006

Torsional vibration is an important vibration mode when shafts, cylinders and pipes are considered. However, the modal testing of torsional vibrations is not an easy task to carry out because of the lack of proper transducers. This work presents a new torsional vibration transducer based on the magnetostrictive principle and its application to torsional modal testing. The transducer is so designed as to generate/measure only torsional vibrations excluding other vibration modes such as longitudinal and bending vibrations. The transducer is composed of ferromagnetic patches bonded to a test structure, permanent magnets, and a solenoid. Though patches and magnets are bonded to a structure, torsional vibrations are generated and measured wirelessly by a solenoid encircling a test structure. The proposed transducer works even at considerably high frequencies, say, tens of kilohertz. Furthermore, the transducer can be manufactured at a low price. To check the performance of the proposed method, the torsional modal testing on a hollow aluminum shaft was conducted. The results, such as eigenfrequencies, obtained by the proposed transducer agreed favorably with theoretical results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.4
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• pp.308-316
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• 2003

Terfenol-D is one of magnetostrictive materials which have the property of converting the energy in magnetic fields into mechanical movement and vice versa. We designed and fabricated a linear magnetostrictive actuator using Terfenol-D. It has 25 mm diameter and 100 mm long. To grasp the characteristics of it, a series of tests were performed in the range of 50 Hz below. Induced-strain actuation displacements of the actuator measured by test and predicted by magnetic analysis agreed well. And blocked forces according to the input currents were estimated from the testing results. Modelling method representing the exerting force of a linear magnetostrictive actuator was confirmed through some testing results.