結構接點勁度與阻尼參數鑑別之迭代修正法

An Iteration Method for Identifying the Joint Stiffness and Damping of Structures

劉宗沛(Tsung-Pei Liu)

指導教授 ： 楊大中 博士

元智大學/工程學院/機械工程學系/碩士(2004年)

摘要

摘要
結構中各種不同的接點，對於結構的靜態和動態特性有很大的影響，而接點亦是結構中最難利用分析方式準確建模的部份。
本實驗室曾發展以修正子結構合成法鑑別結構接點之研究。修正子結構鑑別法為直接法，且所使用之接點模型均未考慮阻尼效應。若鑑別結果不準確時則無後續之修正步驟。而本研究則是要改善此缺點，提出一個有效的模型更新方法應用於結構接點參數鑑別上，利用迭代法來修正直接法鑑別所得之結果。
本文提出以子結構合成法加上迭代修正法來進行結構接點之勁度與阻尼參數鑑別，以直接法之結果做為迭代之初始值開始迭代。而使用迭代法的好處在於可多次修正由直接法所得不準確之結果，使鑑別結果更加準確。迭代方法主要包含了初始值的給定、迭代定義、及中止條件三個部分。整個演算法的重點即在迭代定義之內容。
本文並且提出一套自動化的鑑別流程，將Matlab與ANSYS結合使用，節省了許多人工操作所花費之時間，提升鑑別流程之效率，最後得到相當精確的鑑別結果。
本文將接點阻尼效應加入鑑別模型中，還考慮了結構本身的阻尼效應，使鑑別模型與真實結構更為接近。除此之外，本文的鑑別模型中也加入旋轉與平移耦合的效應。而且本文所提出的鑑別方法在每一頻率上都可鑑別出一組接點參數。
最後利用受螺栓拘束的樑結構做為例子，以驗証本文所提接點鑑別法確可應用於實際案例上。

關鍵字

接點 ； 參數鑑別 ； 模型更新 ； 迭代法

並列摘要

ABSTRACT
Generally, structures include various joints, which have great influence on the static and dynamic characteristics of the structures. The joint is also the most difficult part of the structure to model for analysis purpose. The previous joint identification method proposed by our laboratory is a direct method and the damping effects are not included in the joint model used. If inaccuracy occurs in the final results, no measure is taken to correct the discrepancy between the experimental and analytical results. This research aims at proposing an effective updating method for identification of joint parameters. An iterative improvement algorithm is used to refine the identified results, where the results from the direct method are used as the initial values of the iteration.
The new identification method of structural joint parameters, utilizing substructural synthesis method and iterative improvement method, was developed to identify the stiffness and damping of the bolted joints of a structure. The merit of the iterative improvement method is that the identified parameters are successively refined to achieve more accurate results. The iteration method includes initial values, iteration definitions, and termination conditions. The major work is in the development of the algorithm of the iteration definitions.
An automatic identification procedure integrating the Matlab programs and ANSYS software is employed to save manual operation time, promote the efficiency of the identification processes, and obtain accurate identified results.
In additional to joint stiffness, internal damping of the structure and joint damping are identified, which increase the accuracy of the modeling. The coupled effects of the joint stiffness and damping are also discussed. The advantage of the proposed identification method is that the joint parameters are identified for each frequency.
Finally, a cantilever beam bolted at one of its ends is tested to validate the proposed identification method.

並列關鍵字

Joint ； Parameter Identification ； Model Updating ； Iteration

參考文獻

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