• Title, Summary, Keyword: magneto-rheological elastomer

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The Evaluation of Shock Absorption Performance of Magneto-Rheological Elastomer Through the Drop Impact Test (낙하 충격 실험을 통한 자기유변탄성체의 충격 흡수 성능 평가)

  • Joeng, Kyeong Sik;Lee, Chul Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.92-93
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    • 2013
  • In this study, Shock Absorption performance of Magneto-rheological elastomer(MRE) is identified through the drop impact test. Magneto-rheological materials are divided into two groups by MR fluid in fluid state and MR elastomer in solid state like rubber. The stiffness characteristics of Magneto-rheological material can be changed as magnetic field is applied. The impact loads in MR elastomer were measured under weight of impactor. Experiment results are shown through the experiments to confirm the effect of shock absorption of MR elastomer. Thus, the MR elastomer can be applied to shock absorber used in area that shock occurs.

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A Study of Friction Characteristics in Magneto-Rheological Elastomer (자기유변탄성체 액츄에이터의 마찰특성 연구)

  • Lee, Deuk-Won;Lee, Chul-Hee;Kim, Cheol-Hyun;Cho, Won-Oh
    • Tribology and Lubricants
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    • v.27 no.4
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    • pp.213-217
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    • 2011
  • In this study, friction characteristics using elastomeric actuator with Magneto-rheological (MR) materials are identified. Typically, Magneto-rheological materials are divided into two groups by MR fluid in fluid state and MR elastomer in solid state like rubber. The stiffness characteristics of Magneto-rheological material can be changed as magnetic field is applied. MR fluid has been applied to various industry fields such as to brake, clutch, damper, engine mount and etc. However, MR fluid has been used under the sealed condition to prevent leaking issues. In order to overcome these problems, MR elastomer that has same property as MR fluid has been developed and studied. MR elastomer mainly consists of polymer material such as natural rubber or silicon rubber with particles that can be polarized with magnetic field. And it is called as a smart material since its stiffness and damping characteristics can be changed. In this study, MR elastomer is produced and pin-on-disc tests are carried out to identify the friction characteristics of the material. Several test conditions are applied to evaluate the feasibility to use as a smart actuator in the field of vibration control.

Basic Study for Development of Magneto-rheological Elastomer (자기장 응답형 엘라스토머 개발을 위한 기초연구)

  • Chung, Kyung-Ho;Yoon, Kyu-Seo
    • Elastomers and Composites
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    • v.45 no.2
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    • pp.106-111
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    • 2010
  • Magneto-rheological elastomers (MREs) were manufactured by incorporation of magnetic responsible powder (MRP) into natural rubber and silicone rubber. The optimum loading amounts of MRP was 30 vol.% and the natural rubber based MRE (NR-MRE) showed better mechanical property than that of silicone rubber based MRE (S-MRE). However, the modulus shift ratio caused by S-MRE, measured by Self-modified Electromagnet Applied Fast Fourier Transform Analyser (SEFFTA), was higher than that of NR-MRE. The modulus shift ratio caused by NR-MRE was 10%, while the modulus shift ratio caused by S-MRE was 35.7%. The modulus shift ratio could be improved by orienting the magnetic direction of MRP before crosslinking the MRE. The degree of orientation of MRP was analyzed using SEM.

Application Study of Magneto-Rheological Elastomer to Friction Control (자기유변탄성체의 마찰제어적용 연구)

  • Lian, Chenglong;Lee, Deuk-Won;Lee, Kwang-Hee;Lee, Chul-Hee;Kim, Cheol-Hyun;Cho, Won-Oh
    • Tribology and Lubricants
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    • v.28 no.3
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    • pp.107-111
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    • 2012
  • In this study, application feasibility of Magneto-rheological elastomer to friction control is investigated to identify the reciprocating friction and wear performance in applied magnetic field. Friction and wear of MR elastomerare measured by reciprocating tester by controlling the magnetic field. In the case of applied magnetic field, the coefficient of friction increases as both load and velocity increase. For the case of no magnetic field, the value of coefficient of friction hardly changes during the test. The amount of destruction is measured through cross section images of MR elastomer after tests. The depths of destruction are compared for MR elastomer with or without magnetic field. The results show that the depth of destruction of MR elastomer with magnetic field is deeper than without magnetic field. Based on the obtained results, optimal braking and driving performance can be achieved by controlling the coefficient of friction of MR elastomer, which can be applied to various industrial applications such as driving systems of automobiles and robots.

Effect of Precured EPDM on the Property of Magneto-rheological Elastomer Based on NR/EPDM Blend

  • Na, Bokgyun;Chung, Kyungho
    • Elastomers and Composites
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    • v.53 no.2
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    • pp.67-74
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    • 2018
  • Magneto-rheological elastomers (MREs) are smart materials in which the inherent stiffness and damping properties can be changed by the influence of an external magnetic field. The magneto-rheological (MR) effect depends on the orientation characteristics of the dispersed magneto-responsible particles (MRPs) in the matrix. In this study, natural rubber (NR) and ethylene propylene diene rubber (EPDM) were blended and used as a matrix of an MRE. EPDM was pre-cured before blending with NR. The Mooney viscosity, curing characteristics, and mechanical properties were analyzed with various pre-curing conditions of EPDM and the NR/EPDM blend. The results show that excellent mechanical properties of the NR/EPDM blend-based MRE were obtained when the pre-curing time of EPDM was 60 min. The aging property of the NR-based MRE was improved by the introduction of pre-cured EPDM. Also, the anisotropic MRE showed a higher MR effect than that of the isotropic MRE.

Friction and Wear Properties of Improved Polyurethane Based Magneto-Rheological Elastomer (향상된 폴리우레탄 기반 자기유변탄성체의 마찰 마모 특성연구)

  • Lian, Chenglong;Hong, Sung-Geun;Lee, Kwang-Hee;Lee, Chul-Hee;Kim, Cheol-Hyun
    • Tribology and Lubricants
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    • v.28 no.6
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    • pp.333-339
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    • 2012
  • Typical magneto-rheological (MR) elastomers consist of silicon-based material. A number of studies have been carried out to evaluate the vibration and tribological characteristics of silicon-based MR e-lastomers. However, these elastomers have quite low strength, so they have low wear resistance. In this study, polyurethane-based MR elastomers with performances better than those of MR elastomers. Experiments have been conducted on different MR elastomers (Pu MR elastomer, Pu-Si MR elastomer, and Pu-wrapped-Si MR elastomer) and different predefined magnetic directions (Non-Direction, Vertical Direction, and Horizontal Directionality) to evaluate the friction and wear performance under a magnetic field. The results show that Pu-wrapped-Si MR elastomer with a horizontal predefined magnetic field has the best performance in terms of wear.

Feasibility Study of Squeal Noise Reduction using Magneto-rheological Elastomer (자기유변탄성체를 이용한 스퀼 소음 저감 타당성 연구)

  • Song, HyukGeun;Lee, Chul-Hee
    • Tribology and Lubricants
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    • v.36 no.5
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    • pp.274-278
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    • 2020
  • This study investigates the possibility of reducing squeal noise generated at the contact point between an elastomer and glass by using the properties of a magneto-rheological elastomer (MRE) whose stiffness changes with the application of a magnetic field. Previously, squeal noise was mainly observed in the unstable section caused by the weakening of friction due to velocity. Previous studies have shown that squeal noise decreases as the stiffness increases. Accordingly, this study is conducted to control the unstable area of the friction curve and to reduce the noise by inducing the stiffness change of the MRE by applying a magnetic field. The friction, vibration, and noise characteristics are measured using a reciprocating friction tester. The frequency ranges of vibration and noise measured with the accelerometer and sound sensor show similar results. When a magnetic field is applied to the MRE, there is significantly lower noise compared with the case without the application of the magnetic field. The average coefficient of friction decreases with the application of the magnetic field. The maximum coefficient of friction increases rapidly at the turning point and decreases when the magnetic field is applied. This shows that the mechanical properties of the MRE change due to the magnetic field, and the noise and friction coefficient also decrease.

A Study on Rolling Friction Characteristics of Magneto-Rheological Elastomer under Magnetic Fields (자기장 영향에 따른 자기유변탄성체의 구름 마찰 특성 연구)

  • Lian, Chenglong;Lee, Kwang-Hee;Kim, Cheol-Hyun;Lee, Chul-Hee
    • Tribology and Lubricants
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    • v.30 no.4
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    • pp.234-239
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    • 2014
  • Magneto-rheological elastomer (MR elastomer) is a smart material, because it has mechanical properties that change under a magnetic field. An MR elastomer changes its stiffness characteristics when the inner particles (iron particles) align along the direction of a magnetic field. There has been much research to make use of this characteristic to control vibration issues in various mechanical systems, such as for mounting systems in the automotive field, home appliances, etc. Furthermore, the friction and wear properties of MR elastomer have been studied, as these relate to the durability of the material needed to meet engineering requirements. Rolling friction (or rolling resistance) is one of these friction properties, but has not yet been studied in the context of MR elastomers. In this study, an MR elastomer is fabricated in the shape of a hollow cylinder to evaluate the rolling friction characteristic under a magnetic field. The test apparatus is setup and a strain gauge is used to calculate the rolling resistance under test conditions. Permanent magnets are used to supply the magnetic field during tests. The load and rolling speed conditions are also considered for the tests. The test results show that rolling friction characteristic has a different trend under different magnetic field, load, and rolling speed conditions. It is assumed that the stiffness change of an MR elastomer under a magnetic field has an effect on the rolling friction characteristic of the MR elastomer. For the future work, the rolling friction characteristics of MR elastomers will be controlled by adjusting the strength of the magnetic field using electromagnets.