• Structural Engineering and Mechanics
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• 제17권3_4호
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• pp.303-329
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• 2004

Magnetostrictive materials are routinely employed as actuator and sensor elements in a wide variety of noise and vibration control problems. In infrastructural applications, other technologies such as hydraulic actuation, piezoelectric materials and more recently, magnetorheological fluids, are being favored for actuation and sensing purposes. These technologies have reached a degree of technical maturity and in some cases, cost effectiveness, which justify their broad use in infrastructural applications. Advanced civil structures present new challenges in the areas of condition monitoring and repair, reliability, and high-authority actuation which motivate the need to explore new methods and materials recently developed in the areas of materials science and transducer design. This paper provides an overview of a class of materials that because of the large force, displacement, and energy conversion effciency that it can provide is being considered in a growing number of quasistatic and dynamic applications. Since magnetostriction involves a bidirectional energy exchange between magnetic and elastic states, magnetostrictive materials provide mechanisms both for actuation and sensing. This paper provides an overview of materials, methods and applications with the goal to inspire novel solutions based on magnetostrictive materials for the design and control of advanced infrastructural systems.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.807-808
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• 2008

This is concerned with the radiation pattern of elastic waves in a plate generated by an orientation-adjustable patch-type magnetostrictive transducer. In general, not only the Lamb waves but also shear horizontal (SH) waves are produced by the deformation of the circular magnetostrictive patch bonded to a plate. Among the two types of waves, this paper investigates the radiation patterns of SH waves. A number of experimental results are presented. They are also accurately predicted by a theory developed by the present authors. Experimental findings were explained by a theoretical analysis.

• 한국정밀공학회지
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• 제32권5호
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• pp.483-490
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• 2015

This paper presents a proof-of-concept of a wheel-based magnetostrictive energy harvester (EH), which is a vibration-based EH. Coil-wound Galfenol cantilevers with two permanent magnets (PMs) act EH, while rotating wheels provide a forced vibration to EH. Four different cantilevers are designed and simulated for various end deflection. As expected from the simulation, the cantilever end deflection with triple cavity is the most. Three experiments are conducted to characterize the EH: the first with a magnetostrictive actuator, the second with a motor-driven wheel, and the third with the dummy weights. From the first experiment, the power reaches about 50 mV due to the relatively small displacement of the magnetostrictive actuator. From the second experiment, the power reaches about 120 mW. The power from the Galfenol cantilever is estimated to be about 60% of the total power from the wheel-based magnetostrictive EH.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.153-158
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• 2004

The coupling phenomenon between stress and magnetic induction, known as magnetostriction, has been successfully applied to generate and measure elastic waves. Most applications of this phenomenon thus far, however, are rather limited to cylindrical ferromagnetic waveguides. The main objective of this work is to develop a new patch-type, orientation-adjustable magnetostrictive transducer that is applicable for non-cylindrical, non-ferromagnetic waveguides. The existing patch-type transducer consisting of a ferromagnetic patch and a racetrack coil is useful to generate elastic waves only in one specific direction once the patch is bonded to a test specimen. However, the proposed transducer can transmit and receive elastic waves in any direction only with one patch at a given location. The proposed magnetostrictive transducer consists of a circular nickel patch, a figure-of-eight coil, and a couple of bias permanent magnets. Because of the unique configuration of the transducer, the propagating direction of the generated waves can be freely controlled since the set of bias magnets and the coil is not bonded to the magnetostrictive patch. In this work, the characteristics of the proposed transducer were investigated experimentally.

• 비파괴검사학회지
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• 제31권3호
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• pp.278-286
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• 2011

The on-line monitoring for the wall thinning in secondary system has been considered one of main issues for the safety of nuclear power plants. To establish the on-line monitoring technique for the pipe wall thinning, the development of the ultrasonic transducer working in high-temperature is very important. In this investigation, the magnetostrictive transducer is concerned for high temperature condition up to $300^{\circ}C$. The magnetostrictive transducer has many advantages such as high working temperature, durability, cost-effectiveness, and shear waves, most of all. A thin Fe-Co alloy patch whose Curie temperature is over $900^{\circ}C$ was employed as a ferromagnetic material for magnetostriction. Wave transduction experiments in various temperature were carried out and the effect of bias magnets was considered together with the dry coupling performance of the transducer. From experimental results, consequently, it was found that the magnetostrictive transducer works stable even in high temperature up to $300^{\circ}C$ and can be a promising method for the on-line monitoring of the wall thinning in nuclear power plants.

• 전자공학회논문지SC
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• 제45권1호
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• pp.31-40
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• 2008

본 논문에서는 자기변형재료를 이용한 미세 구동기의 개발과 실시간 제어 알고리즘에 관한 내용을 다룬다. 자기변형재료는 빠른 응답속도, 미세변위동작, 높은 에너지 효율 등의 장점을 가지고 있어 미세 구동기의 재료로 적합하지만 히스테리시스 특성도 함께 갖고 있어 제어에 많은 어려움이 따른다. 본 논문에서는 자기변형재료의 히스테리시스를 제어하기위해 Preisach model을 바탕으로 구동기를 모델링 하였다. 기존의 Preisach 모델은 실험적 데이터를 바탕으로 하기 때문에 정밀한 제어를 하기 위해서는 많은 양의 데이터가 필요하고 결과적으로는 처리해야할 데이터의 양이 많아져 연산하는데 많은 시간이 걸리는 문제가 있다. 본 논문에서는 이러한 문제를 해결하기 위하여 기존의 Preisach 모델의 데이터를 선행 처리하여 일정구간 구동기의 움직임을 저장해 놓은 확장된 Preisach 모델을 제안하였다. 본 논문에서는 Tefenol-D라는 자기변형재료를 사용하여 미세구동기를 제작하고 제어 실험을 통하여 제안된 모델의 우수성을 증명하였다.

• 한국정밀공학회지
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• 제29권11호
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• pp.1214-1220
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• 2012

Vibration assisted cutting (VAC) is one of the promising methods for precision machining, which has been normally equipped with piezoelectric materials. In this paper, a feasibility of applying magnetostrictive materials to VAC as a cutting device instead of piezoelectric materials was studied. For this, the vibrational characteristics of a magnetostrictive material was investigated with respect to a coil design, a preload, and the effects of a biasing and an exciting magnetic fields. The output strain of a magnetostrictive material is restricted due to an increasing inductive impedance as the exciting frequency increases and the heat of coil, etc. Through the experimental results, it was found that the biasing and the exciting magnetic field affected the output performance significantly but not the preload. In conclusion, the magnetostrictive material could be used only in the low frequency range but not a good candidate for high frequency actuating application.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 추계학술대회 논문집
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• pp.247-248
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• 2007

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.497-501
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• 2003

In this paper, impulse response of giant magnetostrictive material (GMM) is identified by using M-transform. First, the displacement of GMM was measured by using the dual frequency laser interferometer. The noise included in the measured signal was removed by using M-transform. The impulse response of the GMM was identified from the input current of the driving coil and the displacement.

• Steel and Composite Structures
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• 제17권4호
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• pp.535-548
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• 2014

In this paper, the exact closed-form solutions for torsional analysis of heterogeneous magnetostrictive circular cylinder are derived. The cylinder is subjected to the action of a magnetic field produced by a constant longitudinal current density. It is also acted upon by a particular kind of shearing stress at its upper base. The rigidity of the cylinder is graded through its axial direction from one material at the lower base to another material at the upper base. The distributions of circumferential displacement and shear stresses are presented through the radial and axial directions of the cylinder. The influence of the magnetostrictive parameter is discussed. The effects of additional parameters are investigated.