VIBRATION CHARACTERISTICS OF THE DAMPER ELEMENT COMPOSED OF ANNULAR MAGNETS AND MAGNETIC FLUID

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1520-1526 ◽  
Author(s):  
S. SUDO ◽  
A. NAKAGAWA
Keyword(s):  
Magnetic Fluid ◽  
Vibration Amplitude ◽  
Permanent Magnets ◽  
Wide Frequency Range ◽  
Vibration Characteristics ◽  
Testing System ◽  
Frequency Range ◽  
Vibration Testing ◽  
Fluid System ◽  
Optical Displacement

This paper is concerned with the development of a damper with excellent characteristics. The vibration characteristics of the damper element composed of two annular permanent magnets and magnetic fluid are studied experimentally using a vibration testing system. The vibration amplitude of the upper magnet-magnetic fluid system is measured with an optical displacement detector system. It was found that the element of two annular permanent magnets adsorbed magnetic fluid is very effective over the wide frequency range.

Vibration Measurement and Monitoring of a Rotating Disk Using Contactless Laser Excitation

2013 ◽  
Author(s):  
Itsuro Kajiwara ◽  
Naoki Hosoya
Keyword(s):  
Laser Doppler Vibrometer ◽  
Rotating Disk ◽  
Disk Drive ◽  
Vibration Characteristics ◽  
Vibration Measurement ◽  
Testing System ◽  
Rotating Disks ◽  
Vibration Testing ◽  
Structural Surface ◽  
Theoretical Analyses

This paper proposes a contactless vibration testing system for rotating disks based on an impulse response excited by a laser ablation. High power YAG pulse laser is used in this system for producing an ideal impulse force on structural surface without contact. The contactless vibration testing system is composed of a YAG laser, laser Doppler vibrometer and spectrum analyzer. This system makes it possible to measure vibration characteristics of structures under operation, such as vibration measurement of a rotating disk. The effectiveness of this system is confirmed by experimental and theoretical analyses. In this paper, a platter of hard disk drive is employed as an experimental object. Vibration characteristics of a rotating and non-rotating platter are measured and compared with the results of theoretical analysis.

Vibrating Properties of a Magnetic-Fluid Tuned Liquid Column Damper with Different U-Pipes

2016 ◽  
Vol 856 ◽  
pp. 21-25 ◽  
Author(s):  
Shinya Kondo ◽  
Kazuki Ikari ◽  
Tatsuo Sawada
Keyword(s):  
Magnetic Field ◽  
Magnetic Fluid ◽  
Wide Frequency Range ◽  
Liquid Column ◽  
Vibration System ◽  
Frequency Range ◽  
Structural Vibrations ◽  
Tuned Liquid Column Damper ◽  
Active Damper ◽  
Liquid Column Damper

A magnetic-fluid tuned liquid column damper (MF-TLCD) is a semi-active damper that has a magnetic fluid column in U-pipe as an additional vibration system. An MF-TLCD can suppress structural vibrations at a wide frequency range by applying a magnetic field. In this study, we performed vibration experiments for three types of U-pipes and assessed the effects on MF-TLCD performance caused by different damping forces on the liquid column.

scholarly journals A Tuned Mass Damper with Nonlinear Magnetic Force for Vibration Suppression with Wide Frequency Range of Offshore Platform under Earthquake Loads

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Qiong Wu ◽  
Wei Zhao ◽  
Weiguo Zhu ◽  
Rencheng Zheng ◽  
Xilu Zhao
Keyword(s):  
High Speed ◽  
Permanent Magnets ◽  
Vibration Suppression ◽  
Wide Frequency Range ◽  
Offshore Platform ◽  
Offshore Platforms ◽  
Frequency Range ◽  
Response Characteristics ◽  
Narrow Frequency Band ◽  
Dynamic Performances

Tuned mass dampers (TMDs) are applied to ensure the safety and stability of offshore platforms; however, linear dampers are effective for a single resonance frequency, providing vibration suppression only within a narrow frequency band. Therefore, this paper proposed a magnetic TMD with two pairs of permanent magnets on both sides of the structures, which can generate a nonlinearly repulsive force, making the magnetic TMD reliable and robust in damping the oscillations of structures with wide frequency range under seismic excitations. A comprehensively numerical and experimental study was processed to investigate the dynamic performances of the proposed magnetic TMD, by application of a 1 : 200-scale prototype of the offshore platform. The results verified that the performance of the magnetic TMD can be significantly improved than that of the linear TMD, meanwhile maintaining high-speed response characteristics. The experimental results indicated that the displacement, acceleration, and frequency responses of the offshore platform can be significantly reduced; furthermore, the evaluation indices showed that the magnetic TMD system is credible in reducing the overall vibration levels and maximum peak values.

Characterisation of the Humming-Type Noise and Vibration of the Automotive HVAC System

2019 ◽  
Vol 16 (2) ◽  
pp. 6634-6648
Author(s):  
A. Z. A. Mazlan ◽  
M. H. A. Satar ◽  
M. H. Hamdan ◽  
M. S. Md. Isa ◽  
S. Man ◽  
...  
Keyword(s):  
Vibration Characteristics ◽  
Operating Conditions ◽  
Hvac System ◽  
Frequency Range ◽  
Noise And Vibration ◽  
Power Steering ◽  
Pump Compressor

The automotive heating and ventilating air condition (HVAC) system, when vibrating, can generate various types of noises such as humming, hissing, clicking and air-rushes. These noises can be characterised to determine their root causes. In this study, the humming-type noise is taken into consideration whereby the noise and vibration characteristics are measured from various HVAC components such as power steering pump, compressor and air conditional pipe. Four types of measurement sensors were used in this study - tachometer for rpm tracking; accelerometer for the vibration microphone for the noise; and sound camera for the visualization measurement. Two types of operating conditions were taken into consideration - they were “idle” (850 rpm) and “running” (850-1400 rpm) conditions. A constant blower speed was applied for both conditions. The result shows that the humming noises can be determined at the frequency range of 300-350 Hz and 150-250 Hz for both idle and running conditions, respectively. The vibration of the power steering pump shows the worst acceleration of 1.8 m/s2 at the frequency range of 150-250 Hz, compared to the compressor and air conditional pipe. This result was validated with the 3D colour order and sound camera analyses, in which the humming noise colour mapping shows dominance in this frequency range.  

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