Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/2728
標題: 變形受制機構自然振動行為之有限元素方法研究
Studies of the Finite Element Method on Natural Vibrational Behaviors of the Mechanism with Deflection Constraints
作者: 羅佐良
T.L.LO
關鍵字: contact vibration;接觸振動;amplitudes constraint;natural frequency;振幅限制;自然振動頻率
出版社: 機械工程學系
摘要: 
在一般的動態問題中,不連續結構體間的接觸常常會引發剛性的改變,像是相互碰觸在一起的結構,或是鬆配合的結合件,甚至是偏心的軸承或鬆脫的螺絲等。這類不連續的結構體可能出現不可預知的自然振幅限制,因而產生無法預期的運動發生,當這些不可預知的振幅限制或是運動發生時,所產生結構自然振動型態的改變,對於高精密度的工程問題如飛行器的設計、高效率引擎,或是衛星結構系統的設計等,是有必要詳加討論研究的。
由於存在著一些不可預知的振幅限制發生的原因,所以在本研究中,針對比較重要的自由度給予振幅限制之條件,對於因此引發之受制運動,其運動方程式,可利用有關的數值分析方法加以研究討論,其中包含板殼的結構。本研究中不僅是探討結構體存在著自然振幅限制條件下的自然振動型態改變,而且提供一些在機械之安全設計上的重要參考依據。
本研究之結果說明自然振幅限制的位置及受制量的大小,會嚴重的影響整個系統的自然振動型態,而且受制的自然振幅位置越靠近結構體邊界時,系統會有更顯著的自然振動型態改變。在較大型結構物中限制自然振幅的位置,對於自然振動型態的改變量是比較小。此外振幅限制對於低頻的模態的影響更為顯著。

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.
URI: http://hdl.handle.net/11455/2728
Appears in Collections:機械工程學系所

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