• Smart Structures and Systems
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• 제16권3호
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• pp.537-554
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• 2015

Magneto-electro-elastic (MEE) materials under thermal environment exhibits pyroelectric and pyromagnetic coefficients resulting in pyroeffects such as pyroelectric and pyromagnetic. The pyroeffects on the behavior of multiphase MEE sensor bonded on top surface of a mild steel cylindrical shell under thermal environment is presented in this paper. The study aims to investigate how samples having different volume fractions of the multiphase MEE sensor behave due to pyroeffects using semi-analytical finite element method. This is studied at an optimal location on a mild steel cylindrical shell, where the maximum electric and magnetic potentials are induced due to these pyroeffects under different boundary conditions. It is assumed that sensor and shell is perfectively bonded to each other. The maximum pyroeffects on electric and magnetic potentials are observed when volume fraction is $v_f$ = 0.2. Additionally, the boundary conditions significantly influence the pyroeffects on electric and magnetic potentials.

• Transactions on Electrical and Electronic Materials
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• 제17권6호
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• pp.335-340
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• 2016

The vibrational energy is prevalent in the natural environment, which is studied by energy researchers as a new energy resource in recent years. Vibration generation utilizes electromagnetic induction technology, piezoelectric technology and certain characteristics of smart materials to convert mechanical energy into electrical energy. In this paper, a new method of using MSMA (magnetic shape memory alloy) to generate electricity is proposed and the principle of generating electricity is demonstrated. Martensitic variants and magnetic domain characteristics of MSMA are analyzed. Combining with Gibbs free energy function thermal theory, the mathematics model of MSMA vibration generator is established. The basic structure of MSMA vibration generator is designed and simulation is done to analyze that the effects of generator output voltage when the input amplitude and frequency of vibration stress change. The simulation experiments verify the feasibility of using MSMA to make the micro vibration generators and the correctness of the mathematical model, which lays a good foundation for the further research and application of MSMA vibration generator.

• 한국자동차공학회논문집
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• 제17권3호
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• pp.22-28
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• 2009

Recently, there has been an active study about smart fluid to control the vibration, in which MR fluid is evaluated as most efficient because it can generate different bonding forces based on the intensity of the external magnetic fields. This paper attempts to find a mechanism that, under limited conditions during a clutch production that uses such dynamic characteristic, defects the maximum intensity of electromagnetism. Using the finite element analysis program, we predicted a change within the bonding force of the MR fluid occurring inside the clutch when it is subjected to an increased electric current. In addition, we analyzed the change in the magnetic intensity when the coil comprising the coil control center is switched to multiple lines from the standard single line, to find a mechanism that can maximize the effect. Based on this analysis, we developed the clutch and tested its function, hoping to widen future MR fluid's range of application.

• Elastomers and Composites
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• 제45권3호
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• pp.188-198
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• 2010

형상 기억 고분자(shape memory polymers, SMPs)는 일정한 온도 또는 특정 자극이 주어졌을 때 가해진 일시적인 변형으로부터 처음 상태로 되돌아 오는 고분자를 말한다. 이러한 형상 기억 고분자는 각종 산업에서 자가 조립 또는 자가 수리가 가능한 스마트 고분자로 분류되어 고부가가치를 지니고 있다. 특히 형상 기억 고분자의 방열 성능, 전기 전도 성능, 물리적 성능, 광학 성능 등은 다양한 충전제를 도입함으로써 향상될 수 있다. 본 논문에서는 형상 기억 고분자의 기본 원리 및 최근의 형상 기억 고분자 나노 복합재료에 대해 알아본다.

• 한국군사과학기술학회지
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• 제27권1호
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• pp.15-23
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• 2024

In order to avoid the high observability due to the cavity resonance or electromagnetic wave leakages from the bridge of a battleship or the cockpit of an aircraft, this paper presents a transparent conductive oxide coated structure to prevent the incoming/outgoing electromagnetic waves. Currently, most of the RCS reduction technologies were focused on radar absorbing material such as paints based on conductive or magnetic materials in the fuselage, and there is not much research on countermeasures for achieving the low observability of materials that required optical transparency in actual weapon systems. In this study, the transmission/reflection and absorption performance of the ITO coated structure according to the change of the surface resistance of the transparent conductor were analyzed. Finally, the relationship between the electromagnetic and optical characteristics was established through fabrication and measurement.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.437-444
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• 2006

Recently, as large structures become lighter and more flexible, the necessity of structural control for reducing excessive displacement and acceleration due to seismic excitation is increased. As a means to minimize seismic damages, various base isolation systems are adopted or considered for adoption. In this study, a base isolation system using Magneto-Sensitive(MS) rubbers is proposed and shown to effectively protect structures against earthquakes. The MS Rubber is a class of smart controllable materials whose mechanical properties change instantly by the application of a magnetic field To demonstrate the advantages of this approach, the MS Rubber isolation system is compared to Lead-Rubber Bearing(LRB) isolation systems and judged based on computed responses to several historical earthquakes. The MS Rubber isolation system is shown to achieve notable decreases in base drifts over comparable passive systems with no accompanying increase in base shears or in accelerations imparted to the superstructure.

• Structural Engineering and Mechanics
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• 제71권3호
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• pp.257-269
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• 2019

This paper develops a nonlocal strain gradient plate model for damping vibration analysis of smart magneto-electro-viscoelastic nanoplates resting on visco-Pasternak medium. For more accurate analysis of nanoplate, the proposed theory contains two scale parameters related to the nonlocal and strain gradient effects. Viscoelastic effect which is neglected in all previous papers on magneto-electro-viscoelastic nanoplates is considered based on Kelvin-Voigt model. Governing equations of a nonlocal strain gradient smart nanoplate on viscoelastic substrate are derived via Hamilton's principle. Galerkin's method is implemented to solve the governing equations. Effects of different factors such as viscoelasticity, nonlocal parameter, length scale parameter, applied voltage and magnetic potential on damping vibration characteristics of a nanoplate are studied.

• Advances in nano research
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• 제7권3호
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• pp.145-155
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• 2019

In this article, the influence of small scale effects on the free vibration response of curved magneto-electro-elastic functionally graded (MEE-FG) nanobeams has been investigated considering nonlocal elasticity theory. Power-law is used to judge the through thickness material property distribution of MEE nanobeams. The Euler-Bernoulli beam model has been adopted and through Hamilton's principle the Nonlocal governing equations of curved MEE-FG nanobeam are obtained. The analytical solutions are obtained and validated with the results reported in the literature. Several parametric studies are performed to assess the influence of nonlocal parameter, magnetic potential, electric voltage, opening angle, material composition and slenderness ratio on the dynamic behaviour of MEE curved nanobeams. It is believed that the results presented in this article may serve as benchmark results in accurate analysis and design of smart nanostructures.

• Smart Structures and Systems
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• 제2권1호
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• pp.61-80
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• 2006

The concept of structural vibration control is to absorb vibration energy of the structure by introducing auxiliary devices. Various types of structural vibration control theories and devices have been recently developed and introduced into mechanical systems. One of such devices is damper employing controllable fluids such as ElectroRheological (ER) or MagnetoRheological (MR) fluids. MagnetoRheological (MR) materials are suspensions of fine magnetizable ferromagnetic particles in a non-magnetic medium exhibiting controllable rheological behaviour in the presence of an applied magnetic field. This paper presents the modelling of an MRfluid damper. The damper model is developed based on Newtonian shear flow and Bingham plastic shear flow models. The geometric parameters are varied to get the optimised damper characteristics. The numerical analysis is carried out to estimate the damping coefficient and damping force. The analytical results are compared with the experimental results. The results confirm that MR damper is one of the most promising new semi-active devices for structural vibration control.

• Smart Structures and Systems
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• 제2권2호
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• pp.155-169
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• 2006

In this paper, the application of magnetoelasticity in static tension monitoring for large steel cables is discussed. Magnetoelastic (EM) stress sensors make contact-free tension monitoring possible for hanger cables and post-tensioned cables on suspension and cable-stayed bridges. By quantifying the correlation of magnetic relative permeability with tension and temperature, the EM sensors inspect the load levels in the steel cables. Cable tension monitoring on Qiangjiang (QJ) 4th Bridge demonstrates the reliability of the EM sensors.