Stiffness and Damping Properties of (Semi) Floating Ring Bearing Using Magnetorheological Fluids as Lubricant

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Xiaohu Wang ◽  
Hongguang Li ◽  
Wen Lu ◽  
Guang Meng
Keyword(s):  
Magnetic Field ◽  
Shear Rate ◽  
Performance Enhancement ◽  
Magnetorheological Fluids ◽  
Model Parameters ◽  
Damping Properties ◽  
Damping Characteristics ◽  
Stiffness And Damping ◽  
The Magnetic Field ◽  
Thinning Effect

Magnetorheological fluids (MRFs) are applicable for achieving semi-active control in smart bearings. For hydrodynamic bearings lubricated with MRF, changes of the viscosity induced by magnetic field lead to changes of the dynamic characteristics such as stiffness and damping properties, providing the controllability to the bearings in rotor applications. Two main defects of the MRF, however, may potentially limit the use of this kind of bearings. One is that the magnetic field-induced viscosity alteration capability decreases as the shear rate increases; the other is the extra friction introduced by iron particles in the MRF in external magnetic field. In this study, the floating ring bearing (FRB) and semi-floating ring bearing (sFRB) are introduced to replace common journal bearing for MRF-lubricated smart bearings. Performance enhancement is achieved using FRB and sFRB. The lubrication behavior of MRF is studied using the Herschel–Bulkley (HB) model that incorporates the yield stress and the shear-thinning effect, which are the two main features of the MRF under shearing. A kind of MRF is developed for lubrication application, and a test rig is setup to measure its shear rate–stress relationship and then to identify its HB model parameters. With the identified HB model, stiffness and damping characteristics of the MRF-lubricated FRB and sFRB are studied. Results show that, compared to MRF-lubricated common journal bearings, the MRF-lubricated FRB and sFRB both achieve better performances in damping enhancement, while limiting the journal friction to a relatively lower degree.

scholarly journals Effect of Curing Current on Stiffness and Damping Properties of Magnetorheological Elastomers

2018 ◽  
Vol 1 (2) ◽  
pp. 51-58 ◽  
Author(s):  
Norhiwani Hapipi ◽  
Saiful Amri Mazlan ◽  
Siti Aishah Abdul Aziz ◽  
Ubaidillah Ubaidillah ◽  
Seung-Bok Choi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Storage Modulus ◽  
Damping Properties ◽  
Magnetorheological Elastomers ◽  
Three Samples ◽  
Viscoelastic Effects ◽  
Dynamic Performances ◽  
Mr Effect ◽  
Stiffness And Damping ◽  
The Magnetic Field

In this study, the viscoelastic effects of the magnetic field strength imposed for curing process on the stiffness and damping properties of magnetorheological elastomers (MREs) are experimentally investigated. In order to observe the effect, three different samples of MRE are fabricated by imposing curing current of 0.1 A, 0.3 A and 0.5 A which is equivalent to the magnetic field of 70 mT, 309 mT, and 345 mT, respectively. All samples consist of 30% silicone rubber and 70% carbonyl iron particles (CIPs) by weight percentages. After observing the morphological images via SEM, the dynamic performances of these samples, such as storage modulus and loss factor are evaluated and compared as a function of the magnetic field intensity or oscillation frequency. It is shown that the sample cured at 0.5A exhibits the highest storage modulus in the frequency domain. In addition, MR effects of three samples are identified, and it is found that the sample cured at 0.5A shows the highest absolute and relative MR effect.

Experimental Investigation into the Effect of a Magnetic Field on Magnetorheological Fluids under an Impact Load

2012 ◽  
Vol 721 ◽  
pp. 179-184
Author(s):  
Ahmad Isnikurniawan ◽  
Yoshitaka Moroka ◽  
Hiromichi Ohba ◽  
Tatsuo Sawada
Keyword(s):  
Magnetic Field ◽  
Experimental Investigation ◽  
Qualitative Analysis ◽  
Apparent Viscosity ◽  
Impact Load ◽  
Magnetorheological Fluids ◽  
Mr Fluids ◽  
Experimental Apparatus ◽  
The Impact ◽  
The Magnetic Field

The apparent viscosity of magnetorheological (MR) fluids changes in the presence of a magnetic field. The stronger the magnetic field applied, the more the apparent viscosity increases. An increase in the apparent viscosity increases the restriction on the flow of MR fluids. In this study, we perform a qualitative analysis to investigate the effect of a magnetic field on MR fluids under an impact load. An experimental apparatus that consists of a drop-test tower was developed to simulate the impact load, and an MR fluid in a U-pipe was subjected to the impact load via a piston rod. In the experiment, we measured the displacement and velocity of the piston rod. On the basis of the results, the influence of a given magnetic field on the behavior of MR fluids under an impact load is discussed.

scholarly journals Application of magnetorheological fluids in the design of a leg prosthesis with active damping

2018 ◽  
Vol 192 ◽  
pp. 02055 ◽  
Author(s):  
Oscar Arteaga ◽  
Alex Cevallos ◽  
Maria I. Erazo ◽  
Klever D. Morales ◽  
Daniel B. Tenezaca ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Applied Load ◽  
Gait Cycle ◽  
Lower Extremities ◽  
Active Damping ◽  
Magnetorheological Fluids ◽  
Biomechanics Of The Foot ◽  
The Impact ◽  
The Magnetic Field ◽  
Leg Prosthesis

The article is about of research of the behavior of magnetorheological materials (MR), later it will be implemented in a prototype leg prosthesis with active damping for people who have suffered amputations in lower extremities, which considers the use of an actuator with Magnetorheological Fluids (MRF) LORD MRF – 140 CG, whose control is based on the adjustment of the magnetic field applied to the MRF using in its design the main parameters of anatomy and biomechanics of the foot-leg system, so that the force applied in the course of the gait cycle it can be absorbed by the prosthesis, reducing the impact on the user's column thus allowing the prosthesis to be subjected to tests for emulation in different positions according to the applied load.

MRE Damping Characteristics Evaluation

2016 ◽  
Vol 699 ◽  
pp. 31-36 ◽  
Author(s):  
Eduard Chirila ◽  
Ionel Chirica ◽  
Doina Boazu ◽  
Elena Felicia Beznea
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Smart Materials ◽  
Magnetorheological Elastomers ◽  
Damping Characteristics ◽  
The Subject ◽  
Energy Absorbing ◽  
The Magnetic Field ◽  
Material Form

The paper addresses the study of the damping characteristics estimation and behaviour of the magnetorheological elastomers (MREs) in the absence of magnetic field. This type of material actively changes the size, internal structure and viscoelastic characteristics under the external influences. These particular composite materials whose characteristics can vary in the presence of a magnetic fields are known as smart materials. The feature which causes the variation of properties in magnetic fields is explained by the existence of polarized particles which change the material form by energy absorbing. Damping is a special characteristic that influences the vibratory of the mechanical system. As an effect of this property is the reducing of the vibration amplitudes by dissipating the energy stored during the vibratory moving. The main characteristic that is based on the determination of the damping coefficient is the energy loss, which is the subject of the present paper. Before to start the characteristics determination in the presence of the magnetic field, it is necessary to study these characteristics in the absence of magnetic field. The MRE specimens have been manufactured and tested under the light conditions (non magnetic field). A special experimental test rig was built to investigate the response of the MRE specimens under the charging force. The experimental results show that the loss energy of the MRE specimen can be determined from the charging-discharging curves versus displacement. The results of the MRE specimen are presented in this paper: MRE with feromagnetic particles not exposed in magnetic field during fabrication.

Modeling of strain kinetics of damping viscoelastic magnetically controlled materials in creep mode

2019 ◽  
Vol 31 (2) ◽  
pp. 243-252
Author(s):  
Evguenia V Korobko ◽  
Mikalai A Zhurauski ◽  
Buhe Bateer ◽  
Zoya A Novikova ◽  
Vladimir A Kuzmin
Keyword(s):  
Magnetic Field ◽  
Experimental Studies ◽  
Magnetic Field Induction ◽  
The Other ◽  
Model Parameters ◽  
Field Induction ◽  
In Series ◽  
Maxwell Models ◽  
Kinetics Of ◽  
The Magnetic Field

The results of experimental studies of strain kinetics of composite magnetically controlled materials in the creep mode with preliminary exposure and without exposure are described by the Burgers model with two elastic and two viscous parameters, which is a combination of viscoelastic Kelvin–Voigt and Maxwell models connected in series. The dependence of the model parameters on the magnetic field induction is determined. The values of elastic and viscous parameters increase with increasing magnetic field induction in the range up to 500 mT by one or two orders of magnitude. It was determined that the value of the viscous Maxwell parameter does not change after preliminary exposure in the field. The values of the other two elastic and viscous Kelvin–Voigt parameters increase with exposure in a magnetic field.

Numerical analysis and simulations of the magnetic field and hydrophobicity effect on the journal bearing dynamics

2016 ◽  
Vol 231 (5) ◽  
pp. 561-571 ◽  
Author(s):  
Simona Fialová ◽  
František Pochylý ◽  
Eduard Malenovský
Keyword(s):  
Magnetic Field ◽  
Mathematical Models ◽  
Reynolds Equation ◽  
Hydrophobic Surface ◽  
Hydrophilic Surface ◽  
Flowing Liquid ◽  
Stiffness And Damping ◽  
Bearing Dynamics ◽  
The Magnetic Field ◽  
Generalized Reynolds Equation

The article contains mathematical models of Reynolds equation with the effects of hydrophobicity of surface and magnetic field. The first section provides a new mathematical model of the solution of the generalized Reynolds equation and its application for a hydrophilic surface. It also derives a new boundary condition for the contact of a flowing liquid with a hydrophobic surface. This wettability condition is defined in dependence on the adhesion coefficient k. The second part presents mathematical models of Reynolds equation including the effect of hydrophobia and magnetic field. For all problems, the solutions are shown and the definitions of the stiffness and damping matrices of the liquid layer are outlined. From the results, it can be deduced that hydrophobic surface significantly affects the velocity profile of the liquid. It leads to a higher effect of the Lorentz force and thus of the magnetic field in comparison with a hydrophilic surface of the bearing lining.

Temperature Behavior of Magnetorheological Fluids

2005 ◽  
Vol 15 (2) ◽  
pp. 116-121 ◽  
Author(s):  
F. Zschunke ◽  
R. Rivas ◽  
P.O. Brunn
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Fluid Flows ◽  
Magnetorheological Fluids ◽  
Fluid Viscosity ◽  
Damping Force ◽  
Friction Dampers ◽  
Fluid Behavior ◽  
Magnetorheological Effect ◽  
The Magnetic Field

AbstractMagnetorheological fluids (MRFs) show a high but reversible rise of the viscosity upon application of an external magnetic field. This effect can be utilized in controllable friction dampers where the MR fluid flows through a gap with a adjustable magnetic field. The change in the magnitude of the magnetic field leads to a change of the viscosity of the fluid which in turn effects the pressure drop in the system. So the damping force can be controlled by the magnitude of the external magnetic field. This energy dissipation leads to a rise of the damper temperature. For designing those dampers it is vital to know the influence of the geometry, which influences the magnetic field strength, as well as the flow properties and the temperature dependence of the magnetorheological effect. An approach to the solution of this problem is shown by using an Arrhenius relationship, where the fluid viscosity is a function of the shear rate, the magnetic field and the temperature. The aim of the here presented research is to show how the fluid behavior can be simply modeled for use in CFD codes to design dampers or other applications.

Simulation of the influence of constant uniform magnetic field on a miniature LIT mass spectrometer

2017 ◽  
Vol 24 (2) ◽  
pp. 196-205 ◽  
Author(s):  
Yan Feng ◽  
Xiaoqiang Pei ◽  
Yongjun Cheng ◽  
Wenjun Sun ◽  
Gang Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Mass Spectrometer ◽  
Performance Enhancement ◽  
Ion Trap ◽  
Ion Trapping ◽  
Trapping Efficiency ◽  
Application Development ◽  
Ion Cloud ◽  
The Magnetic Field

In this paper, the effects of constant uniform magnetic fields on a miniature linear ion trap mass spectrometer with hyperbolic electrodes are simulated using SIMION 8.0 3D software. Magnetic fields in different directions have different effects on the trajectories of the trapped ions and the shape of the ion cloud. When the magnetic field is applied in the z-direction, namely the ion injection direction, the magnetic field will cause the ions focusing to the z-axis, and exert a compression effect on the ion cloud. When the magnetic field is applied in the x-y plane, the original ion cloud will be expanded due to the action of the applied magnetic field, and the ion cloud plane after expansion is always perpendicular to the direction of the magnetic field. The discovery of influence field of magnetic will bring some useful inspiration for the improvement of ion trapping efficiency, mass resolution, sensitivity and trapping capacity, which is conductive to the performance enhancement utilization of magnetic field, even in the industrial application development and other aspects.

STATISTICAL EVALUATION OF ELECTRICAL SOUNDlNG METHODS. PART I: EXPERIMENT DESIGN

Geophysics ◽  
1976 ◽  
Vol 41 (6) ◽  
pp. 1207-1221 ◽  
Author(s):  
W. E. Glenn ◽  
S. H. Ward
Keyword(s):  
Magnetic Field ◽  
Tilt Angle ◽  
Experiment Design ◽  
Eigenvalue Decomposition ◽  
Earth Model ◽  
Model Parameters ◽  
Design Technique ◽  
Horizontal Magnetic Field ◽  
Geophysical Surveys ◽  
The Magnetic Field

Traditional experiment design techniques, widely applied to both linear and nonlinear problems in many scientific fields, is applicable to the design of exploration geophysical surveys. The design technique is formulated using the mathematics of the generalized inverse and its construction via eigenvalue decomposition. The design technique is demonstrated by the designing of electromagnetic sounding surveys for a horizontal loop source. The experiment is designed whereby it is determined (1) which one of the electromagnetic field quantities, vertical and horizontal magnetic field amplitudes or phases, and polarization ellipse quantities, tilt angle, and ellipticity, and (2) which set of transmitter and receiver separations and transmitter frequencies, best resolve the conductivities and thicknesses of a given layered earth model. Model resolution is sensitive to the data error. As an example, for different assumed data errors, a model is best resolved in one instance by the phase of the two components of the magnetic field, while in another instance it is best resolved by tilt angle and ellipticity measurements. The best designs are obtained using field measurements made at several transmitter frequencies and at two or more transmitter and receiver separations. The functional relationship between the earth model parameters and the magnetic field quantities is nonlinear. The effect of this nonlinearity on the statistics applied in the method of experiment design has been reported in the literature and is reexamined here. Based on Beale's measure of nonlinearity, the models studied here exhibit adequate linearity to permit use of the linear statistics for experiment design. A study of the eigenvectors and information density matrix provide insight to model parameter correlations and measurement correlations which can be exploited for improving the design of an experiment.

Improving machining stability of AISI-4140 with magnetic field

2022 ◽  
pp. 095440622110649
Author(s):  
Mehmet Alper Sofuoglu ◽  
Fatih Hayati Çakir
Keyword(s):  
Magnetic Field ◽  
Surface Roughness ◽  
Cutting Temperature ◽  
Cutting Parameters ◽  
Magnetic Flux Density ◽  
Machining Processes ◽  
Aisi 4140 ◽  
Neodymium Magnets ◽  
Stiffness And Damping ◽  
The Magnetic Field

Several methods have been developed in order to improve the traditional machining processes and machining outputs. In this study, the effect of the magnetic field on the turning process was investigated. AISI-4140 was machined with different cutting speeds and magnetic flux density magnitudes. The magnetic field was generated with neodymium magnets. Machining stability, surface roughness, and maximum cutting temperature were measured. Additionally, chip shapes were examined. The machining stability was determined by measuring the vibration amplitude and other vibrational parameters (natural frequency, stiffness, and damping coefficients). Conventional turning and magnetic assisted turning were performed under the same cutting parameters consecutively, and the results were compared. According to the results, it was observed that neodymium magnets attached to the cutting tool improve machining stability and damping properties. Surface roughness was decreased between 6%–10% in magnetic assisted turning. Furthermore, it has been observed that the maximum cutting temperatures have been increased between 10%–45% in the magnetic assisted machining. Besides, it can be said that magnets contribute to improving chip control by collecting the chips on them while machining AISI-4140 steel.

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