الفهرس 
chapter 1Only 14 pages are availabe for public view
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Abstract
The objective of the present thesis is to study the influence of using vibration isolators in the form of post-buckled elastic clamped-clamped struts to relief the vibrating machines from the harmful effects of vibration. The advantage of the post-buckled state is that it can ideally support more static load with a relatively small static deflection than traditional vibration isolators such as springs or rubber mounts. In addition, it can also exhibit a low axial stiffness when it is subjected the dynamic excitation is making it ideal for isolating vertical vibrations. Several modern machinery, such as compressors, internal combustion engines, hydraulic, and pneumatic presses, turbo machinery, etc. undergo uncomfortable and even undesirable serious vibrations. These vibrations are in most cases uncontrollable and lead to sudden failure and in turn to a loss of machines availability. Mathematical models are introduced within the present thesis consisting of pre-bent post-buckled struts acting as vibration isolators supporting a symmetric and asymmetric loading rigid bar and rigid plate. The models are subject to axial harmonic excitation at the base, and allowed to displace laterally with respect to axial center line of the isolated plate. The displacement transmissibility is considered as the governing parameter of the isolator’s effectiveness at the mitigating vibrations transmitted from the base to the rigid bar or plate. The main objective of this thesis is to determine the displacement transmissibility of the system such that the struts reduce unwanted vibrations. The transmissibility is calculated over a wide range of frequencies and plotted in form of design charts to define its influence on the vibration behavior of the struts. The lateral motion of the plate and the bar is taken into consideration. The transmissibility plots are used to recognize the ranges of frequencies, at which isolation can be maintained. The resonance frequencies of the system can be easily depicted from the design graphs. Seven models consisting of buckled or pre-bent struts serving as vibration isolators which support a rigid bar and a rigid plate are examined in this research.
The present study reveals that at resonance frequencies the most effective transmissibility is well below unity. Vibration characteristics are determined under specific frequencies such that the physical behavior of the system can be thoroughly analyzed. All variables used in the analysis are normalized, such that the results aren’t dependent on any material or geometric property. In this way, the obtained results can be effectively applied over a wide range of similar configurations.