Modeling of the Dynamic Surface Profile in Magnetic Fluid Mirrors

Advances in Bioengineering, Biomedical and Safety Systems ◽

10.1115/imece2006-16045 ◽

2006 ◽

Author(s):

Azhar Iqbal ◽

Foued Ben Amara

Keyword(s):

Magnetic Field ◽

Dynamic Response ◽

Magnetic Fluid ◽

Retinal Imaging ◽

Surface Shape ◽

Effective Control ◽

Control Input ◽

Mirror Surface ◽

Dynamic Surface ◽

Imaging Application

Magnetic fluid deformable mirrors (MFDMs) present a simple alternative to the expensive and delicate wavefront correctors currently in use in adaptive optics (AO) systems. Such mirrors are particularly suitable for retinal imaging AO systems. The practical implementation of a retinal imaging AO system incorporating a MFDM requires an effective control system to control the shape of the mirror surface. The real-time control of the mirror surface requires a model of the mirror that can be used to determine the dynamic response of the mirror to a magnetic field applied as the control input. This paper presents such a model that not only determines the dynamic response of the MFDM but also takes into account the unique requirements of the retinal imaging application of the mirrors. The mirror is modeled as a horizontal layer of a magnetic fluid. The dynamic response of the mirror to the applied magnetic field is represented by the deflection of the free surface of the layer. The surface deflection is determined by the modal analysis of the coupled fluid-magnetic system. Considering the requirements of the retinal imaging application, the effects of surface tension and depth of the fluid layer are duly represented in the model. The mirror model is described in a state-space form and can be readily used in the design of a controller to regulate the mirror surface shape.

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Development of a dynamic surface shape measurement for magnetic fluid

Flow Measurement and Instrumentation ◽

10.1016/j.flowmeasinst.2019.01.021 ◽

2019 ◽

Vol 66 ◽

pp. 50-59

Author(s):

Xining Zhang ◽

Zhou Xiang ◽

XinRui Xia ◽

Haixing Zhang

Keyword(s):

Magnetic Fluid ◽

Surface Shape ◽

Shape Measurement ◽

Dynamic Surface

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Characteristic Parameters of a Tuned Magnetic Fluid Damper Under Magnetic Fields

Volume 2: Fora, Parts A and B ◽

10.1115/fedsm2007-37533 ◽

2007 ◽

Author(s):

Ken-Ichi Ohno ◽

Manabu Shimoda ◽

Tatsuo Sawada

Keyword(s):

Magnetic Field ◽

Magnetic Fluid ◽

Magnetic Fluids ◽

Tuned Mass Damper ◽

Surface Shape ◽

Cylindrical Container ◽

Characteristic Parameters ◽

Frequency Responses ◽

Fluid Damper ◽

Mass Damper

Damping parameters of a tuned magnetic fluid damper [TMFD] using a tuned mass damper [TMD] analogy model are obtained from approximation to frequency responses of experiments used some sort of magnetic fluids in a cylindrical container. An effective mass is changed by a magnetic field from downside, however a significant change of surface shape of magnetic fluids causes strange changing tendency. It was found that other parameters are changed according to the surface shape.

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An Online Active Balancing Method Using Magnetorheological Effect of Magnetic Fluid

Journal of Vibration and Acoustics ◽

10.1115/1.4040675 ◽

2018 ◽

Vol 141 (1) ◽

Cited By ~ 3

Author(s):

Xining Zhang ◽

Xinrui Xia ◽

Zhou Xiang ◽

Yanan You ◽

Bing Li

Keyword(s):

Magnetic Field ◽

Machine Tool ◽

Magnetic Fluid ◽

Three Dimensional ◽

Surface Shape ◽

Local Magnetic Field ◽

Work Piece ◽

Active Balancing ◽

Machine Tool Spindle ◽

Mr Effect

The improvement of machining efficiency and precision puts forward new requirements for the balancing performance of machine tool spindle. Work piece quality can be effectively improved by implementing the active balance on the spindle. In this paper, a new active balancing method using magnetorheological (MR) effect of magnetic fluid is proposed. The mechanism of forming compensation mass by changing the distribution of magnetic fluid under local magnetic field is expounded. Experiments are carried out to verify the feasibility of the proposed method. Profile lines of magnetic fluid surface shape at different positions are measured with linear laser projection measurement method in experiments. Three-dimensional (3D) surface shape of the magnetic fluid is reconstructed by the synthesis of the measured profile lines. Experiments demonstrate that mass center of the magnetic fluid increases with the strength of magnetic field. Thus, the feasibility of the proposed method is verified experimentally. In order to weaken the vibration of machine tool spindle using this method, a balancing device is designed, which includes magnetic fluid chambers and three conjugated C-type electromagnets arranged at 120 deg intervals. For each electromagnet, the relationship among compensation mass (the corresponding balancing mass), excitation current, and rotation speed is established. Also, the performance of the balancing device is further proved in experiments conducted on the experimental platform. The imbalance vibration amplitude of the test spindle decreased by an average of 87.9% indicates that the proposed active balancing method in this paper is promising.

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2303 Dynamic Response of Small Magnet encompassed with Magnetic Fluid in Magnetic Field

The proceedings of the JSME annual meeting ◽

10.1299/jsmemecjo.2006.2.0_19 ◽

2006 ◽

Vol 2006.2 (0) ◽

pp. 19-20

Author(s):

Seiichi SUDO ◽

Yuichi KUROSU ◽

Tetsuya YANO ◽

Hirokatsu HONMA

Keyword(s):

Magnetic Field ◽

Dynamic Response ◽

Magnetic Fluid

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Magnetic fluid bridge between two cones and a cylinder in the magnetic field of a current-carrying wire

EPJ Web of Conferences ◽

10.1051/epjconf/201818509010 ◽

2018 ◽

Vol 185 ◽

pp. 09010

Author(s):

Alexandra S. Vinogradova ◽

Vladimir A. Turkov ◽

Vera A. Naletova

Keyword(s):

Magnetic Field ◽

Pressure Drop ◽

Numerical Modelling ◽

Magnetic Fluid ◽

Surface Shape ◽

Zero Current ◽

The Wire ◽

The Magnetic Field ◽

A Current ◽

Hysteresis Phenomena

A magnetic fluid (MF) changes its surface shape in the magnetic field of a current-carrying wire while the current is changing. In the present paper, we propose to study a MF bridge which can open or close the channel formed by two cones and a cylinder by imposing the magnetic field of a wire. Numerical modelling of the bridge behavior for different values of MF volumes and currents in the wire is done for two cases: when the MF wets and does not wet surrounding solid boundaries. It is shown that the presence of limiting cones allows the MF to sustain the pressure drop which is much higher in case of non-wetting than in case of wetting. In case of wetting, the MF cannot sustain any pressure drop at low currents, but in case of non-wetting, the MF can do it even at zero current. It is found that in case of non-wetting, spasmodic and hysteresis phenomena are possible for some values of MF volumes and currents in the wire. The use of a MF in valves, dispensers and pumps is one of possible actuation methods.

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