Isolation Properties of Low-Profile Magnetorheological Fluid Mounts

This study evaluates the stiffness and damping characteristics of low-profile magnetorheological (MR) fluid mounts (MRFM) to provide a better understanding of the vibration improvements offered by such mounts, as compared with conventional elastomeric mounts. It also aims at assessing how much of the mount’s performance is due to the MR fluid and how much is due to the elastomer and steel insert that is used in MRFM. The study includes the design, analysis, fabrication, and testing of a unique class of MRFM that is suitable for the isolation of sensitive machinery and sensors. The MR fluid is compressed (squeezed) in response to dynamic force applied to the mount. The test results are compared with conventional elastomeric (rubber) mounts of the same configuration as MRFM, to highlight the changes in stiffness and damping characteristics for frequencies ranging from 1 to 35 Hz. With no current supplied, the MRFM has a slightly higher stiffness and nearly the same damping as a conventional rubber mount. The slight increase in MRFM stiffness is attributed to the MR fluid’s compressive stiffness, which is higher than the rubber. When current is supplied to the MRFM, the stiffness and damping increase significantly at lower frequencies and taper off to nearly the same level as the rubber mount at higher frequencies. Both the stiffness and damping are directly proportional to the supplied current. At the maximum current of 2 A, the MRFM has 200% higher stiffness and 700% higher damping than the rubber mount. The significantly higher damping and stiffness and the tapering off to nearly the same level as the rubber mount is quite interesting and intriguing. It indicates that MRFM delivers high damping and stiffness when needed, while significantly tapering them off when high damping and stiffness are not desirable.

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Dynamic characteristics of squeeze-type mount using magnetorheological fluid

Proceedings of the Institution of Mechanical Engineers Part K Journal of Multi-body Dynamics ◽

10.1243/146441905x10005 ◽

2005 ◽

Vol 219 (1) ◽

pp. 27-34 ◽

Cited By ~ 5

Author(s):

Y K Ahn ◽

J-Y Ha ◽

Y-H Kim ◽

B-S Yang ◽

M Ahmadian ◽

...

Keyword(s):

Dynamic Characteristics ◽

Experimental Analysis ◽

Vibration Isolation ◽

Dynamic Behaviour ◽

Electrical Current ◽

Magnetorheological Fluid ◽

Test Set ◽

Mr Fluid ◽

Set Up ◽

Stiffness And Damping

This paper presents an analytical and experimental analysis of the characteristics of a squeeze-type magnetorheological (MR) mount which can be used for various vibration isolation areas. The concept of the squeeze-type mount and details of the design of a squeeze-type MR mount are discussed. These are followed by a detailed description of the test set-up for evaluating the dynamic behaviour of the mount. A series of tests was conducted on the prototype mount built for this study, in order to characterize the changes occurring as a result of changing electrical current to the mount. The results of this study show that increasing electrical current to the mount, which increases the yield stress of the MR fluid, will result in an increase in both stiffness and damping of the mount. The results also show that the mount hysteresis increases with increase in current to the MR fluid, causing changes in stiffness and damping at different input frequencies.

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Experimental and Theoretical Rotordynamic Characteristics of a Hybrid Journal Bearing

Journal of Tribology ◽

10.1115/1.2832446 ◽

1997 ◽

Vol 119 (1) ◽

pp. 132-141 ◽

Cited By ~ 17

Author(s):

J. T. Sawicki ◽

R. J. Capaldi ◽

M. L. Adams

Keyword(s):

Journal Bearing ◽

Operating Conditions ◽

Dynamic Force ◽

Test Results ◽

Force Measurements ◽

Lubrication Equation ◽

Load Cells ◽

Theoretical Predictions ◽

Stiffness And Damping

This paper describes an experimental and theoretical investigation of a four-pocket, oil-fed, orifice-compensated hydrostatic bearing including the hybrid effects of journal rotation. The test apparatus incorporates a double-spool-shaft spindle which permits independent control over the journal spin speed and the frequency of an adjustable-magnitude circular orbit, for both forward and backward whirling. This configuration yields data that enables determination of the full linear anisotropic rotordynamic model. The dynamic force measurements were made simultaneously with two independent systems, one with piezoelectric load cells and the other with strain gage load cells. Theoretical predictions are made for the same configuration and operating conditions as the test matrix using a finite-difference solver of Reynolds lubrication equation. The computational results agree well with test results, theoretical predictions of stiffness and damping coefficients are typically within thirty percent of the experimental results.

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Dynamic Force Coefficients of a Multiple-Blade, Multiple-Pocket Gas Damper Seal: Test Results and Predictions

Journal of Tribology ◽

10.1115/1.555360 ◽

1999 ◽

Vol 122 (1) ◽

pp. 317-322 ◽

Cited By ~ 4

Author(s):

Jiming Li ◽

Ramon Aguilar ◽

Luis San Andre´s ◽

John M. Vance

Keyword(s):

Control Volume ◽

Pressure Ratio ◽

Flexible Structure ◽

Dynamic Force ◽

Test Results ◽

Force Coefficients ◽

Exit Pressure ◽

Identification Technique ◽

Gas Damper ◽

Stiffness And Damping

Experimental rotordynamic force coefficients and leakage for a four-blade, two-four pocket gas damper seal are presented and compared to predictions based on a one control volume bulk-flow model. The test rig comprises a vertical shaft and a test seal housing and flexible structure suspended from a rigid centering frame. The experiments were conducted at increasing rotor speeds to 6000 rpm and inlet/exit pressure ratios from 1.0 to 3.0. The seal force coefficients are obtained from impact response measurements of the seal and flexible structure using a frequency domain parameter identification technique. Both measurements and predictions show the seal direct stiffness and damping coefficients are proportional to the inlet/exit pressure ratio and insensitive to rotor speed. The agreement between experimental results and analytical predictions is acceptable. Predicted cross-coupled stiffness coefficients are of small amplitude. However, the test results evidence cross-coupled stiffnesses without journal rotation due to a structural asymmetry induced by the external pressurization into the seal. [S0742-4787(00)04201-6]

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Stiffness and damping characteristics of MR fluid-based sandwich beams: experimental study

Journal of Theoretical and Applied Mechanics ◽

10.15632/jtam-pl.56.3.571 ◽

2018 ◽

pp. 571 ◽

Cited By ~ 2

Author(s):

Mateusz Romaszko ◽

Bogdan Sapiński

Keyword(s):

Experimental Study ◽

Sandwich Beams ◽

Mr Fluid ◽

Damping Characteristics ◽

Stiffness And Damping

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Experimental Response of Simple Gas Hybrid Bearings for Oil-Free Turbomachinery

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.1839922 ◽

2006 ◽

Vol 128 (3) ◽

pp. 626-633 ◽

Cited By ~ 12

Author(s):

Deborah A. Osborne ◽

Luis San Andre´s

Keyword(s):

High Speed ◽

Damping Ratio ◽

Dynamic Force ◽

Test Results ◽

Low Friction ◽

Foil Bearings ◽

Feed Pressure ◽

Micropower Generators ◽

Lift Off ◽

Stiffness And Damping

Gas film bearings offer unique advantages enabling successful deployment of high-speed microturbomachinery (<0.4 MW). Current applications encompass micropower generators, air cycle machines and turbo expanders. Mechanically complex gas foil bearings are in use; however, their excessive cost and lack of calibrated predictive tools deters their application to mass-produced systems. The present investigation provides experimental results for the rotordynamic performance of a small rotor supported on simple and inexpensive hybrid gas bearings with static and dynamic force characteristics desirable in high-speed turbomachinery. These characteristics are adequate load support, stiffness and damping coefficients, low friction and wear during rotor startup and shutdown, and most importantly, enhanced rotordynamic stability. The test results evidence the paramount effect of feed pressure on early rotor lift-off and substantially higher threshold speeds of rotordynamic instability. Higher supply pressures also determine larger bearing direct stiffnesses, and thus bring an increase in the rotor-bearing system critical speed albeit with a reduction in damping ratio.

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Experimental Response of Simple Gas Hybrid Bearings for Oil-Free Turbomachinery

Volume 4: Turbo Expo 2003 ◽

10.1115/gt2003-38833 ◽

2003 ◽

Cited By ~ 3

Author(s):

Deborah A. Wilde ◽

Luis San Andre´s

Keyword(s):

High Speed ◽

Damping Ratio ◽

Dynamic Force ◽

Test Results ◽

Power Generators ◽

Foil Bearings ◽

Feed Pressure ◽

Micro Power ◽

Lift Off ◽

Stiffness And Damping

Gas film bearings offer unique advantages enabling successful deployment of high-speed micro-turbomachinery (< 0.4 MW). Current applications encompass micro power generators, air cycle machines and turbo expanders. Mechanically complex gas foil bearings are in use; however, their excessive cost and lack of calibrated predictive tools deter their application to mass-produced systems. The present investigation provides experimental results for the rotordynamic performance of a small rotor supported on simple and inexpensive hybrid gas bearings with static and dynamic force characteristics desirable in high-speed turbomachinery. These characteristics are adequate load support, stiffness and damping coefficients, low friction and wear during rotor startup and shutdown, and most importantly, enhanced rotordynamic stability. The test results evidence the paramount effect of feed pressure on early rotor lift off and substantially higher threshold speeds of rotordynamic instability. Higher supply pressures also determine larger bearing direct stiffnesses, and thus bring an increase in the rotor-bearing system critical speed albeit with a reduction in damping ratio.

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Experimental Evaluation of Magnetorheological Damper Characteristics for Vibration Analysis

International Journal of Vehicle Structures and Systems ◽

10.4273/ijvss.10.1.07 ◽

2018 ◽

Vol 10 (1) ◽

Author(s):

S. Siva Kumar ◽

K.S. Raj Kumar ◽

Navaneet Kumar

Keyword(s):

Vibration Isolation ◽

Mr Damper ◽

Magnetorheological Damper ◽

Damping Force ◽

Mr Fluid ◽

Damping Characteristics ◽

Fluid Damper ◽

Mr Fluid Damper ◽

Stiffness And Damping ◽

Theoretical Results

Magnetorheological (MR) fluid damper has been designed, fabricated and tested to find the stiffness and damping characteristics. Experimentally the MR damper has been tested to analyse the behaviour of MR fluid as well as to obtain the stiffness for varying magnetic field. MR damper mathematical model has been developed for evaluating dynamic response for experimentally obtained parameters. The experimental results show that the increase of applied electric current in the MR damper, the damping force will increase remarkably up to the saturation value of current. The numerical simulation results that stiffness of the MR damper can be varied with the current value and increase the damping forces with the reduced amplitude of excitation. Experimental and theoretical results of the MR damper characteristics demonstrate that the developed MR damper can be used for vibration isolation and suppression.

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Torsional Vibration Semiactive Control of Drivetrain Based on Magnetorheological Fluid Dual Mass Flywheel

Mathematical Problems in Engineering ◽

10.1155/2015/608737 ◽

2015 ◽

Vol 2015 ◽

pp. 1-17 ◽

Cited By ~ 5

Author(s):

Qing-hua Zu ◽

Zhi-yong Chen ◽

Wen-ku Shi ◽

Yang Mao ◽

Zhi-yuan Chen

Keyword(s):

Torsional Vibration ◽

High Performance ◽

Magnetorheological Fluid ◽

Semiactive Control ◽

Test Results ◽

Resonance Amplitude ◽

Damping Characteristics ◽

Driving Condition ◽

Control System Model ◽

Damping Torque

The damping characteristics of the traditional dual mass flywheel (DMF) cannot be changed and can only meet one of the damping requirements. Given that the traditional DMF cannot avoid the resonance interval in start/stop conditions, it tends to generate high-resonance amplitude, which reduces the lifetime of a vehicle’s parts and leads to vehicle vibration and noise. The problems associated with the traditional DMF can be solved through the magnetorheological fluid dual mass flywheel (MRF-DMF), which was designed in this study with adjustable damping performance under different conditions. The MRF-DMF is designed based on the rheological behavior of the magnetorheological fluid (MRF), which can be changed by magnetic field strength. The damping torque of the MRF-DMF, which is generated by the MRF effect, is derived in detail. Thus, the cosimulation between the drivetrain model built in AMESim and the control system model developed in Simulink is conducted. The controller of MRF-DMF is developed, after which the torsional vibration control test of drivetrain is carried out. The cosimulation and test results indicate that MRF-DMF with the controller effectively isolates torque fluctuation of the engine in the driving condition and exhibits high performance in suppressing the resonance amplitude in the start/stop conditions.

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