Presentations -

Effect of a Core in TMFD with Different Coaxial Cylindrical Containers

Ken-ichi Ohno and Tatsuo Sawada

18th MAGDA Conference in Tokyo (Tokyo) , 

2009.11

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Poster presentation, The Japan Society of Applied Electromagnetics and Mechanics

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同調磁性流体ダンパー（TMFD）とは磁場により特性変化をもたらす制振装置であり，制振効果のある振動数を変化させることができる。TMFDでは制振質量として磁性流体を用いており，流体の容器には任意形状のものが使用できる。流体容器として二重円筒容器を用いた場合に，二重円筒容器中央の空洞部に鉄心を挿入すると制振効果のある振動数の変化量が増大する。この変化量の増大効果を半径比の異なる二重円筒容器について調べた。

Improvement of a Tuned Magnetic Fluid Damper with a Coaxial Cylindrical Container

Ken-ichi Ohno, Hayato Suzuki and Tatsuo Sawada

JSME Fluids Engineering Conference 2009 (Nagoya) , 

2009.11

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Oral presentation (general), JSME

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スロッシング固有振動数を変化させることが可能である。磁性流体の容器として同軸二重円筒容器を用いた場合，TMFDにおける鉄心による制御領域改善効果を周波数応答測定により実験的に求めた。

Effects of vertical motion on a fluid pressure and a surface displacement in a tuned magnetic fluid damper

Ken-ichi Ohno and Tatsuo Sawada

The 14th International Symposium on Applied Electromagnetics and Mechanics (Xi'an) , 

2009.09

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Oral presentation (general), Xi'an Jiaotong University

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A magnetic fluid damper (TMFD) uses hydrodynamic force of sloshing of a magnetic fluid to dampen oscillation. Hydrodynamic force and displacement of surface of the fluid in the TMFD change according to the forced amplitude. Hydrodynamic force changes linearly with surface displacement. The changing rate between hydrodynamic force and surface amplitude varies around a characteristic forced frequency.

Hysteresis phenomena of ultrasonic velocity change in magnetorheological fluids

Muhammad Agung Bramantya, Hiroki Takuma and Tatsuo Sawada

The 14th International Symposium on Applied Electromagnetics and Mechanics (Xi'an) , 

2009.09

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Poster presentation, Xi'an Jiaotong University

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We proposed a qualitative analysis of these effects by measuring properties of ultrasonic propagation. Hysteresis was appeared when magnetic field increased to and decreased from the certain value, 290 mT in our experiment. The change rate of the ultrasonic wave propagation velocity increased during the increasing process of the external magnetic field. However, it was kept almost the same value during the decreasing process.

Study on the effect of the volume fraction in magnetorheological fluids

Muhammad Agung Bramantya, Hiroki Takuma and Tatsuo Sawada

JSME Mechanical Engineering Congress, 2009 Japan(MECJ-09) (Morioka) , 

2009.09

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Oral presentation (general), JSME

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内部微粒子の濃度変化がMR流体内の超音波伝播特性におよぼす影響を，実験的に調べた。

The effect of volume fraction on the clustering structures of magnetorheological fluids by ultrasonic investigation

Muhammad Agung Bramantya, Hiroki Takuma and Tatsuo Sawada

The 6th Japanese-Mediterranean Workshop on Applied Electromagnetic Engineering for Magnetic, Superconducting and Nano Materials (Bucharest) , 

2009.07

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Poster presentation, Politehnica University of Bucharest

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The rheological response of magnetorheological fluid (MRF) results from the polarization induced in the suspended particles by application of an external magnetic field. Characteristics of an MRF depend on the volume faction, that is the percentage of magnetic particles in the carrier liquid. We propose a qualitative investigation of these volume fraction effects by measuring properties of ultrasonic wave propagation velocity in MRFs having various volume fractions. The ultrasonic wave propagation velocity changes under the effect of an external magnetic field as a result of arrangement of clusters along the direction of the field in the MRF.

Characteristics of hydrodynamic pressure of a magnetic fluid in a tuned magnetic fluid damper

Ken-ichi Ohno and Tatsuo Sawada

The 6th Japanese-Mediterranean Workshop on Applied Electromagnetic Engineering for Magnetic, Superconducting and Nano Materials (Bucharest) , 

2009.07

, 

Oral presentation (general), Politehnica University of Bucharest

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A tuned magnetic fluid damper (TMFD) is a semi-active dynamic absorber using a magnetic fluid as a damping mass. A characteristic of the TMFD is to change a natural frequency of a sloshing. When a magnetic field is applied to a container filled with a magnetic fluid from below, the natural sloshing frequency increases and a range of a damping frequency is spread. In this paper, pressure measurements were used to control the appropriate magnetic field.

Hysteresis change of ultrasonic wave velocity in magnetorheological fluid

Muhammad Agung Bramantya, Hiroki Takuma and Tatsuo Sawada

The 21th Symposium on Electromagnetics and Dynamics (Nagano) , 

2009.05

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Oral presentation (general), The Institute of Electrical Engineers of Japan

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Applying magnetic field changes properties of a magnetorheological (MR) fluid. A fascinating occurrence so called hysteresis in the MR fluid appears when the magnetic field is increased to and decreased from a certain value. This occurrence appears to be influenced by the formation of clusters in proportion to the magnetic field intensity and its direction. Results show that the hysteresis in MR fluid is changes when the direction of ultrasonic measurement also changes. The change of hysteresis curve is related to the cluster formation.

Controllable Frequency Area on a TMFD with a Coaxial Cylindrical Container

Ken-ichi Ohno　and Tatsuo Sawada

The 21th Symposium on Electromagnetics and Dynamics (Nagano) , 

2009.05

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Oral presentation (general), The Institute of Electrical Engineers of Japan

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A natural frequency of a tuned magnetic fluid damper (TMFD) changes in a mganetic field. Change of the natural frequency of the TMFD with a coaxial cylindrical container is smaller than that with a cylindrical container. The natural frequency of the TMFDs varies according to a theory of the cylindrical container qualitatively. When a maximum supplied current to an electromagnet is constant, a variation area of the natural frequency does not change linearly with a radius-ratio of a inner and a outer cylinders. There is an optimum radius-ratio in the TMFD with the coaxial cylindrical container.

Hysteresis change of ultrasonic wave velocity in MR fluid caused by the magnetic field

Muhammad Agung Bramantya, Hiroki Takuma and Tatsuo Sawada

日本機械学会関東支部第15期総会講演会 (Mito) , 

2009.03

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Oral presentation (general), JSME

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MR流体に磁場を印加した時に内部に生じるクラスター成長を超音波の伝播速度変化を用いて実験的に調べた。ある一定の磁場強度に達するまでの時間を変化させ，超音波伝播速度がどのように変化するかを調べた。また，同じ時間を費やして磁場を減少させ，ヒステリシスに関する検討を行った。

Numerical investigation on the performance of Wells turbine with the NACA0020 blade profile for wave energy conversion

Sugiyono, Zahari Taha and Tatsuo Sawada

日本機械学会関東支部第15期総会講演会 (Mito) , 

2009.03

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Oral presentation (general), JSME

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波力発電用の往復流型タービン翼にNACA0020を用いたウェールズタービンの諸性能を，数値計算によって調べた。計算には，FLUENTを使用した。チップ間隔を変化させ，タービン性能がどのように変化するかについて検討を行った。

Ultrasonic velocity anisotropy of MR fluids

Muhammad Agung Bramantya, Hiroki Takuma, Mohd Faiz and Tatsuo Sawada

Japanese Symposium on Magnetic Fluids (Tanabe) , 

2008.12

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Oral presentation (general), 磁性流体研究連絡会

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磁場印加によるMR流体中を伝播する超音波特性変化を実験的に調べた。

Ultrasonic study on clustering structures of a magneto-rheological fluid under uniform magnetic fields

Muhammad Agung Bramantya, Hiroki Takuma and Tatsuo Sawada

17th MAGDA Conference in Hitachi (Hitachi) , 

2008.11

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Poster presentation, The Japan Society of Applied Electromagnetics and Mechanics

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The properties of ultrasonic propagation velocity of MR fluids are measured accurately. The effect of time is focused in this study when an external magnetic field applied. Based on these results, the inner structure is analyzed empirically. The application of non-contact inspection by ultrasonic techniques is discussed.

Numerical analysis on the effect of hub–nose (position and shape) on pressure characteristic in an oscillating water column system

Sugiyono, Zahari Taha1 and Tatsuo Sawada

The 7th JSME-KSME Thermal and Fluids Emgineering Conference (Sapporo) , 

2008.10

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Oral presentation (general), JSME

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液体振動を用いた発電システムに用いるタービン翼のハブの形状と設置位置に関する検討を数値シミュレーションによって行った。

Time-Dependent Ultrasonic Propagation Properties of a MR Fluid under Magnetic Fields

Hiroki Takuma, Muhammad Agung Bramantya and Tatsuo Sawada

2008 Annual Meeting, Japan Society of Fluid Mechanics (Kobe) , 

2008.09

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Oral presentation (general), Japan Society of Fluid Mechanics

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MR流体に磁場を印加した時の2MHzの超音波伝播速度の経時変化を調べた。また，長時間磁場印加後，磁場印加を止めてからの超音波伝播速度の経時変化も調べた。その結果，印加磁場強度，と内部微粒子の沈降との関係を定性的に見出した。

Experimental analysis of clustering structures in magnetic and MR fluids using ultrasound

Muhammad Agung Bramantya, Masaaki Motozawa, Hiroki Takuma, Mohd Faiz and Tatsuo Sawada

The 11th International Conference on Electrorheological Fluids and Magnetorheological Suspensions (Dresden) , 

2008.08

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Poster presentation, Technical University of Dresden

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MR流体中を伝播する超音波の音速が，印加磁場強度，印加時間，印加方向によってどのように変化するかを実験的に詳細に調べた。そして，内部に形成される磁性体微粒子のクラスター構造と印加磁場の関係について検討を行った。

Nonlinearity for fluid surface shape on a tuned magnetic fluid damper

Ken-ichi Ohno and Tatsuo Sawada

Asia-Pacific Symposium on Applied Electromagnetics and Mechanics 2008 (Bangkok) , 

2008.07

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Oral presentation (general), King Mongkut's University of Technology Thonburi

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同調磁性流体ダンパーの自由表面上の磁場による盛り上がりや自由表面に形成されるスパイクの影響について実験的に検討を行った。

Ultrasonic propagation velocity in magneto rheological fluid under a uniform magnetic field

Muhammad Agung Bramantya, Hiroki Takuma, Mohd Faiz and Tatsuo Sawada

Asia-Pacific Symposium on Applied Electromagnetics and Mechanics 2008 (Bangkok) , 

2008.07

, 

Oral presentation (general), King Mongkut's University of Technology Thonburi

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MR流体に一様磁場を印加した時の，超音波伝播速度を実験的に調べた。磁場印加時間や磁場除去後の特性について検討を行った。

Responses of a Tuned Magnetic Fluid Damper to Change of Certain Parameters

Ken-ichi Ohno, Yuki Honjo, Tatsuo Sawada

The 20th Symposium on Electromagnetics and Dynamics (Beppu) , 

2008.05

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Oral presentation (general), Japan Society of Applied Electromagnetics and Mechanics

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TMFD（同調磁性流体ダンパー）の固有振動数は縦方向の非一様定常地場によって変化させることができる。TMFDの解析にはTMDのアナロジーを利用した解析モデルを用いる。サイズの異なる２種類のTMFDを制作し周波数応答を測定した。実験で得た周波数を元に特定のTMDパラメータを変化させて近似曲線を算出し，実験曲線と比較した。また，TMFDの温度依存性を知るために，数種の温度下の磁性流体について周波数応答を測定した。共振点と最大制振点の振幅は変化しなかったが，振幅については流体の温度によって変化した。

Influence of Inner Structure in a Magnetic Fluid on Ultrasonic Propagation

Masaaki Motozawa, Hiroki Takuma, Mohd Faiz, Tatsuo Sawada

The 20th Symposium on Electromagnetics and Dynamics (Beppu) , 

2008.05

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Oral presentation (general), Japan Society of Applied Electromagnetics and Mechanics

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磁性流体に磁場を印加すると内部強磁性微粒子がクラスターを形成することが知られており，印加磁場強さ，磁場印加時間などに応じて複雑に変化する。磁性流体中を伝播する超音波は，この内部構造変化に伴い，様々な特性を有する。本研究では，様々な磁場印加条件のもと，磁性流体中の超音波伝播速度，減衰を詳細に測定し，磁場印加等による内部構造変化がもたらす超音波伝播への影響を検討した。