Magnetic fluid actuator

Olaru, Radu; Sălceanu, Alexandru; Calarasu, D.; Cotae, C.

doi:10.1016/s0924-4247(99)00177-6

Cited by 16 publications

(12 citation statements)

References 5 publications

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“…In some of our papers a new type of actuator which generates mechanical actions due to the magnetic forces exerted on a non-magnetic disc within the ferrofluid was described [5,6]. The actuator can be simple (with one magnetic inductor) or differential (with two inductors).…”

Section: Introductionmentioning

confidence: 99%

Magnetic actuator with ferrofluid and non-magnetic disc

Olaru

Petrescu

Hertanu

2010

JAE

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The paper studies an actuator based on magnetofluidic forces acting on a non-magnetic disc plunged into a ferrofluid that is exposed to a non-uniform magnetic field generated by magnetic inductor(s). The input output equations (force -current and displacement -current) that describe the behaviour of two types of actuators are established. The expression of the force generated on the nonmagnetic disc is determined analytically for the particular conditions imposed by the two actuator configurations: a) simple, with one magnetic inductor; b) differential, with two inductors. The derived relations enable a comparative study of the two types of actuators. The results show the superior performance of the differential actuator. The latter was tested as a current to displacement transducer in an electropneumatic converter.

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Section: Introductionmentioning

confidence: 99%

Magnetic actuator with ferrofluid and non-magnetic disc

Olaru

Petrescu

Hertanu

2010

JAE

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“…Meanwhile, a ferrofluid with iron-nitride particles was examined to increase the controlling force. Besides, the structure of a piston immersed in a ferrofluid can be also used as an actuator, and this concept was verified by Olaru et al [40,41] from Romania who has done a rather in-depth study till now.…”

Section: Ferrofluid Vibration Isolatorsmentioning

confidence: 81%

Damping Applications of Ferrofluids: A Review

Huang¹,

Yao²,

Zhang³

et al. 2017

Journal of Magnetics

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Ferrofluids are a special category of smart nanomaterials which shows normal liquid behavior coupled with superparamagnetic properties. One of the earliest and most prospective applications of ferrofluids is in damping, which has prominent advantages compared with conventional damping devices: simplicity, flexibility and reliability. This paper presents the basic principles that play a major role in the design of ferrofluid damping devices. The characteristics of typical ferrofluid damping devices including dampers, vibration isolators, and dynamic vibration absorbers are compared and summarized, and then recent progress of vibration energy harvesters based on ferrofluid is briefly described. Additionally, we proposed a novel ferrofluid dynamic vibration absorber in this paper, and its damping efficiency was verified with experiments. In the end, the critical problems and research directions of the ferrofluid damping technology in the future are raised.

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“…(1) (2) ．磁性流体や MR サスペンションは外部磁場により磁気粘性効果の発現および内部構造変化などの特性を示し，ダンパー，アクチュエータ，ならびに磁気記録材料への工学的応用を念頭に置いた研究がなされてきた (3)- (5) ．磁性流体および MR サスペンションに用いられる強磁性微粒子として，これまで主に球状酸化鉄粒子が用いられてきた．また近年，Fe-Pt 粒子 (6) (7) ，ならびに，コバルトフェライト粒子 (8) (9) などの高い保磁力を有する球状磁性微粒子の検討が行われている．一方，球状磁性粒子に代えて非球状磁性微粒子を用いることで新規機能性流体および新規機能性材料の高機能化が可能になるため，種々の形状を有する磁性微粒子 * 原稿受付 *1 正員，元秋田県立大学システム科学技術学部機械知能システム学科 *2 正員，秋田県立大学システム科学技術学部機械知能システム学科 (〒015-0055 秋田県由利本荘市土谷字海老ノ口 84-4) E-mail: asatoh@akita-pu.ac.jp が創製されている．種々の形状を示す磁性微粒子としてヘマタイト粒子がある．このヘマタイト粒子は調製法の違いにより，針状 (10) (11) ，扁平状 (12)- (14) ，ならびにキューブ状 (15) (16) などの形状を示す粒子が創製可能である．特に針状ヘマタイト粒子は粒子の短軸方向に磁化されており (10) (17) ，さらにマグネタイト粒子と比較して非常に弱い磁化を示す (17) (18) ．このため，粗大な針状ヘマタイト粒子は弱い磁化および粒子表面の電気 2 重層により，界面活性剤を用いなくても可逆的な凝集体を形成する．このように針状ヘマタイト粒子は強磁性棒状粒子とは異なる特徴を有している．このため，針状ヘマタイト粒子を機能性微粒子として用いることで，磁性流体や MR サスペンションとは異なる新規機能性流体の創製が期待できる．以上のような背景より，針状ヘマタイト粒子分散系を対象としたレオロジー特性に着目した種々の研究がなされてきた (19) (20) ．針状ヘマタイト粒子分散系の磁気粘性効果に着目した理論解析では，せん断流に対し垂直に磁場を印加すると，磁気力に基づく粘度が負になる逆磁気粘性効果の発生が理論的に予測されている (21) (22) ．また，コーン・プレート型粘度計による実験的検証により，針状ヘマタイト粒子分散系に逆磁気粘性効果が発生することが確認された (23) ．一方，せん断流と同方向に磁場を印加すると磁気力に基づく粘度が正の値になり，せん断流の回転角速度方向の印加磁場では磁気粘性効果が生じないことが理論解析により明らかになっている (24) …”

Section: 磁場に応答する機能性微粒子を母液に懸濁することで得られるコロイド分散系はせん断流および磁場により種々の機能性を発揮するunclassified

Influence of External Magnetic Field Direction on Orientational Distribution and Rheological Properties in a Dilute Suspension Composed of Spindle-Like Hematite Particles (Analysis with Consideration of Spin Rotational Brownian Motion)

Satoh

2013

Trans.JSME, Ser.B

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We have theoretically investigated the particle orientational and rheological properties of a dilute suspension composed of spindle-like hematite particles under a simple shear flow. We have derived the basic equation of the orientational distribution function with spin rotational Brownian motion. The basic equation has been solved numerically in order to investigate the influence of the shear rate, magnetic field strength, and rotational Brownian motion on the orientational distribution and rheological properties. For a very strong magnetic field applied in the shear flow direction, the particle inclines in the direction normal to the flow direction. Also, the particle is restricted in a plane normal to the shearing plane due to the spin rotational Brownian motion. The viscosity becomes large with increasing magnetic field strength. In the case of an external magnetic field applied in the direction of the angular velocity of a simple shear flow, the particle inclines toward a plane normal to the shearing plane, while the magnetic moment is restricted in the direction of the magnetic field. The particle can easily rotate around the magnetic moment under circumstances of a weak shear flow. For a strong shear flow, the particle inclines in the shear flow direction and does not rotate around the magnetic moment. The viscosity due to magnetic properties does not occur under the situation of a magnetic field applied in the direction of the angular velocity vector of a simple shear flow.

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Magnetic fluid actuator

Cited by 16 publications

References 5 publications

Magnetic actuator with ferrofluid and non-magnetic disc

Magnetic actuator with ferrofluid and non-magnetic disc

Damping Applications of Ferrofluids: A Review

Influence of External Magnetic Field Direction on Orientational Distribution and Rheological Properties in a Dilute Suspension Composed of Spindle-Like Hematite Particles (Analysis with Consideration of Spin Rotational Brownian Motion)

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