非定常環境振動之模態參數識別

Modal Parameter Identification Using Non-Stationary Ambient Vibration Data

10.6124/TAASRC.200512_37(4).02

江達雲(Dar-Yun Chiang)；林章生(Chang-Sheng Lin)；曹松華(Sung-Hwa Tsao)

相關函數法 ； 隨機遞減法 ； 非定常環境振動 ； 模態參數 ； Ibrahim識別法 ； Correlation technique ； Random decrement technique ； Non-stationary ambient vibration ； Identification of modal parameters ； Ibrahim time-domain technique

中國航空太空學會學刊

37卷4期（2005 / 12 / 01）

293 - 299

繁體中文

本文探討如何利用非定常環境振動下之結構系統響應進行模態參數識別。在假設外力爲具乘積模型形式之非定常白訊下，分別應用相關函數法與隨機遞減法，將量測信號轉成近似自由振動衰減信號，再利用Ibrahim時域法進行模態參數識別，並利用模態可信度來確認識別模態。當激勵爲非定常有色訊號時，透過濾波器概念可識別系統模態，再利用模態正交性可將激勵模態與結構模態加以區分。

Identification of system characteristics is usually accomplished using both input and output data from the structural system. In many cases, however, only output measurements are available for structures under ambient vibration conditions. It can be shown that if the input signals can be modeled as non-stationary white noise, which is a product of white noise and a deterministic time-varying function, the theoretical correlation functions and random decrement signatures of structural response will have the same mathematical form as free vibration of the structure. In the present paper, the Ibrahim Time Domain method is employed to extract modal parameters from vibration data that have been processed by the correlation function method or the random decrement method. Through numerical simulation, the applicability of the modal parameter identification method proposed is confirmed.