Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1478
標題: 螺栓結合界面之模擬與實驗驗證
Modeling and Experimental Identification of Bolted Joints
作者: 劉連富
關鍵字: 最佳化;模態;模態標準規範;勁度;正交異向性材料;自然振動頻率;特徵向量;特徵值
出版社: 機械工程學系
摘要: 
界面勁度之正確模擬攸關有限元素分析之結果,界面層勁度之模擬在以往都是以彈簧元素來進行模擬,此種方式雖然可以達到模擬界面之目的,但在建構有限元素模型上卻要花費很多的時間。本文是以三維正交異向性材料來模擬中間界面層元素,這個方法不僅可以完整的表現出界面層不同方向上的勁度特性,同時也可以減少建構有限元素模型的時間。
界面層的正交材料中之楊氏係數及剪力模數為驗證調整的對象,配合模態實驗量測到的自然振動頻率和局部模態,並結合最佳化方法來修正有限元素模型,最佳化的目標是減少數個實驗頻率和有限元素模型分析頻率的差,以實驗和分析振型的相似性為限制條件,使修正後的有限元素模型自然振動頻率最接近實驗量測的頻率並維持模態的正確性。本文亦對不同螺栓直徑與不同螺栓鎖緊扭力對界面層勁度之影響作討論。

The correct modeling of interfaces affects the results of finite element analysis. The stiffness of interface was usually modeled by spring elements. Although this approach achieves the purpose of modeling interfaces, the time spent on creating the finite elements model is significant. This thesis uses orthotropic interface element to simulate the stiffness of interface. The stiffnesses in the three orthotropic directions can be easily modeled. The time spent on modeling the interfaces is greatly reduced.
The design variables used for modeling the interface are Young's moduli and shear moduli. The modal test is performed to get the test frequencies and partial mode shapes. The optimization method is used to find the optimum values of Young's and shear moduli. The objective of the optimization is to minimize the differences of measured and analyzed natural frequencies. The constraints are imposed to guarantee a certain value of modal assurance criterion between measured and analyzed mode shapes. The refined finite element model is expected to be more reliable. The effect of different torques and diameters of bolts on the stiffness of interface will be discussed.
URI: http://hdl.handle.net/11455/1478
Appears in Collections:機械工程學系所

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