Vibration isolation under an elastic foundation

Pao Yue-kong Library Electronic Theses Database

Vibration isolation under an elastic foundation

 

Author: Lee, Tsz-yuen
Title: Vibration isolation under an elastic foundation
Degree: M.Eng.
Year: 2011
Subject: Vibration.
Damping (Mechanics)
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Building Services Engineering
Pages: xiii, 102, [24] leaves : ill. (chiefly col.) ; 30 cm.
InnoPac Record: http://library.polyu.edu.hk/record=b2449802
URI: http://theses.lib.polyu.edu.hk/handle/200/6242
Abstract: Different building services machines such as pumps, chillers and fans are usually placed in one mechanical plant room. Vibration may be transmitted indoors through the building structure as structure-borne sound. The vibration transmitted may generate noise which causes noise disturbance to residents inside the building. Although vibration isolation at the support of those machines can reduce the vibration transmitted and isolate them from the building structure, all of these machines produce vibration with unbalanced rotating shafts and unsteady forces to affect the isolation efficiency. One of the vibration isolators may affect other isolators under supporting foundation. Although much research focused on the vibration isolation of mass-spring-dashpot system approach between machines and structure, little has been conducted study on the influence of the efficiency between different vibration isolators under elastic foundation at supporting points. Therefore, this study is an investigation on the effects of the vibration isolation under an elastic foundation. In this project, a physical model was used to simulate the most practical situation of vibration isolation under an elastic foundation in a mechanical plant room. Also, the transverse wave equation of the beam motion supported by elastic foundation with a single and multiple force excitation were developed and compared with the experiment results. This study also defined, analyzed and validated from the experiment results. It is found that the resultant motion of the beam is obviously influenced by the magnitude and the frequency of the applied force and the vibration profile is contributed by the cross mobility. The study will be useful to engineers who are concerned about controlling building noise and vibration.

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