Studies of the Finite Element Method on Natural Vibrational Behaviors of the Mechanism with Deflection Constraints

碩士 === 國立中興大學 === 機械工程學系 === 87 === Contact of non-continuous structures may cause changes of it’s rigidity and is a general problem occurred in most of the kinetics problems, such as copular structures, loose-match components, even wear down biased bearing or unfasten bolts, etc. Such ki...

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Bibliographic Details
Main Authors: T.L.LO, 羅佐良
Other Authors: J.S.S.Wu
Format: Others
Language:zh-TW
Published: 1999
Online Access:http://ndltd.ncl.edu.tw/handle/21277153104547890690
Description
Summary:碩士 === 國立中興大學 === 機械工程學系 === 87 === Contact of non-continuous structures may cause changes of it’s rigidity and is a general problem occurred in most of the kinetics problems, such as copular structures, loose-match components, even wear down biased bearing or unfasten bolts, etc. Such kinds of non-continuous structures may obviously appear unpredictable constraints on the natural amplitudes causing unexpected motions. When unpredictable constraints or motions appear, the natural frequencies of such structures are changed and its natu-ral behaviors must be reconsidered. Such problems must be particularly considered for the design of high precision engineering systems such as aircraft design, advanced engine development, satellite system design, etc. In the study, general equations of motion for natural behaviors under constraints of motion (constraints on the vibrational amplitudes) caused by unpredictable reasons on some selected, significant degrees-of-freedom, are developed and some related fundamental numerical studies are per-formed, including plates and shells. This study may not only explore the effect of the amplitude constraints on natural behaviors of structures but also provide significant information for the safety machine design. The calculating results tell that the location and restricted magnitude on natural amplitudes may affect overall system natural behaviors seriously. When the boundary to restrict the natural amplitudes is more close to the structures, the more on the effect of the natural behaviors of the structures may appear. When the structures are large, the constraints of natural mo-tion will probably affect the natural frequencies considerable small de-pending on the location of the restriction. Furthermore, the low frequency modes may be affected by the restriction of amplitudes significantly.