結構分解之應用與研究

The Dynamic Decoupling of a Structure by Using Frequency Response Functions

林欽裕(Alber Chin-Yuh Lin) ； 張玉清(Yuh-Chin Chang)

《中華民國振動與噪音工程學會論文集》 1993 (1993/06) Pp. 269-277

https://doi.org/10.30028/CSSVANNUAL.199306.0269

摘要

本文研究的目的，是要瞭解當一個子結構從系統中被抽出或發生斷裂時，剩餘子結構的動態特性。為了決定剩餘子結構的動態特性，吾人可利用系統及被抽出或發生斷裂之子結構在斷點上的頻率響應函數，及斷點的幾何相容性和力平衡方程式，來求得所欲知剩餘子結構的自然頻率，進而求取其振型，而頻率響應函數除可利用理論分析及有限元素法求得之外，亦可直接以模態測試取得。此種方法與結構合成所應用之模力法(Modal Force Technique)非常相似，可視為模力法之對偶律(Duality)。它不需作反矩陣的運算，同時減少分析所需的計算時間及記憶空間，能有效求得複雜結構的自然頻率及振型。
經由實例之驗證，顯示此法可有效地用來預測剩餘子結構之動態特性，有助於設計之參考。

關鍵字

結構分解 ； 模力法 ； 頻率響應函數

並列摘要

In order to investigate the dynamical behavior of the remainder substructure which is extracted or broken from a system, a decouple method is presented. In this method the frequency response functions (FRF's) of the system and the extracted or broken substructure at broken joints are directly used. The boundary conditions of geometric compatibility and force equilibrium equation at broken joints lead the formulation of the remainder substructure equation which in turns to determine the desired natural frequencies, as well as the mode shape. This decouple method is quite similar to the Modal Force Technique (MFT) which is recently developed for structural synthesis. It can be regarded as a duality of the Modal Force Technique. It has many advantages such as required no matrix inversion, fewer order of system matrix, and the system matrix containing both of system and substructure information.
The numerical results indicate that this method is effective and can be used for design process.