• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.187-189
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• 2002

This paper presents property of the squeeze mode type mount using Magneto-Rheological fluid(MR fluid). The mount can isolate multi-directional vibrations, and also effectively reduce the vibrations in a wide range of disturbance frequencies by controlling the applied magnetic field. The shape of the mount is the same that of squeeze film damper. In the present work, the performance of this mount was experimentally investigated according to changing the magnetic field strength.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.325.1-325
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• 2002

This paper presents property of the squeeze mode type mount using Magneto-Rheological fluid (MR fluid). The mount can isolate multi-directional vibrations, and also effectively reduce the vibrations in a wide range of disturbance frequency by controling the applied magnetic field. The shape of the mount is the same that of squeeze film damper. In the present work, the performance of this mount was experimentally investigated according to changing the magnetic field strength. (omitted)

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.8-13
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• 2003

Equivalent Reynolds equation of truncated cone type SFD bearing using nonnewtonian EV fluid is derived. The 3 nondimensional oil film pressures and its forces are obtained with axial and circumferential pressure gradient of bearing respectively, and dynamic characteristics for the stability of rotor-bearing system are obtaind through the governing equation for an elastic rotational shaft. It is shown that EV fluid is less sensitive to the changes of oil-film than newtonian fluids for dynamic characteristics. Therefore, results show that it is better to use an EV fluid with truncated cone type SFD bearing for the vibration control of rotational machines.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1286-1291
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• 2000

A new electro-rheological squeeze film damper (ER SFD) has been sealed with slotted piston rings which have electrodes at the inside of the constant gap. The slotted ER SFD can prevent the problem of electric discharge which might be occurred in the previous configuration of an ER SFD. The current paper presents the extraction of linearized dynamic coefficients within small orbit where these coefficients are controlled by the application of electric strength. Test rig has been modified to isolate the damper section for dynamic coefficient extraction. The results show that rotordynamic coefficients, damping and inertia terms, increase with increasing supply voltages, while stiffness coefficients decrease with increasing supply voltages. Rotating speed of rigid Shaft does not affect these coefficients.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.340.2-340
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• 2002

A practical implementation method of squeeze-film aeroelastic disk vibration damping and its practical design performance are presented to provide a solution method to meet the tight TMR(Track Mis-Registration) design budget of high-TPI HDDs. Most previous research results are mainly based on the component-level study in the 'open-cover state' which is far from the realistic operations HDD condition. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.342.1-342
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• 2002

In this work, the dynamic characteristics of an oil-lubricated, short SFD with a central feeding groove are derived based on a theoretical analysis considering the effect of a groove. The validity of the analysis is investigated experimentally using an Active Magnetic Bearing (AMB) system as an exciter. For the theoretical solution, the fluid film forces of a grooved SFD are analytically derived so that the dynamic coefficients of a SFD are expressed in terms of its design parameters. (omitted)

• Tribology and Lubricants
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• v.34 no.1
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• pp.9-15
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• 2018

Modern high-performance automotive turbochargers (TCs) implement ceramic hybrid angular contact ball bearings in series with squeeze film dampers (SFDs) to enhance transient responses, thereby reducing the overall emission levels. The current study predicts the rotordynamic responses of the commercial automotive TCs (compressor wheel diameter = ~53 mm, turbine wheel diameter = ~43 mm, and shaft diameter at the bearing locations = ~7 mm) supported on ball bearings and SFDs for various design parameters of SFDs, including radial clearance, axial length, lubricant viscosity, and rotor imbalance conditions (i.e., amplitudes and phase angles) while increasing rotor speed up to 150 krpm. This study validates the predictive rotor finite element model against measurements of mass, polar and transverse moments of inertia, and free-free mode natural frequencies and mode shapes. A nonlinear rotordynamic model integrates nonlinear force coefficients of SFDs to calculate the transient responses of the TC rotor-bearing system. The predicted results show that SFD radial clearances, as well as phase angles of rotor imbalances, have the paramount effect on the dynamic responses of TC shaft motions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.7
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• pp.517-523
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• 2003

This paper presents response property of the squeeze mode type mount using Magneto-Rheological fluid (MR fluid) . The MR mount for the isolation of multi-directional vibrations was constructed in this study. Both the mechanism and shape of the mount are the same as squeeze film dampers for a rotor system. In the present work, the performance of the mount was experimentally Investigated according to the magnetic field strength. The experimental results present that the MR mount can effectively reduce the vibration in a wide range of frequency by controlling the applied electromagnetic filed strength. Viscous damping and stiffness coefficients of the MR mount tend to be changed according to the variation of the applied currents In this study.

• Tribology and Lubricants
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• v.5 no.2
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• pp.101-106
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• 1989

Various squeeze film dampers have been theoretically and experimentally studied for flexible rotors. A cylindrical bush damper among them was selected and applied in a test rotor supported with ball bearings. A quiet running of the rotor over a critical speed was observed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.521-527
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• 2001

The dynamic performance analyses and tests for a 50kW turbo-generator (KIMM-TG50) were carried out. The operating concept of this machine is that it gets the initial driving force from the built-in motor-generator until it reaches its self-sustaining speed of 40,000 rpm, and then the driving mode is changed to self-operating mode by the combustor installed between the centrifugal compressor and the turbine. Due to winding mistake of motor-generator, the system could go only up to 22000 rpm by the motor so that high pressure air externally fed into the turbine was utilized to get the system to run up to 62,000 rpm thereafter. The vibration data collected during the tests revealed that the first bending critical speed is in near 5,600 rpm as predicted in the design stage of the rotor-bearing system, and that there were no other identifiable critical speeds up until 62,000 rpm due to high damping from the squeeze film damper-bearings supporting the rotor. This paper presented some of the experimental results along with dynamic performance predictions made in the design stage as a part of progress being made.