The Identification of Structural Dynamic Parameters by Auto- Regressive Model

• Main Authors: Tai, Chih-Hao, 戴志豪
• Other Authors: Hung C. F.
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/08227556726875958047

碩士 === 國立臺灣大學 === 造船工程學系 === 85 === Abstract In this paper we develop an identification system of dynamical parameters, which are determined by the measured data from multiple I/O channels of structures. The modal parameters, natural frequency, damping ratio, mode shape and frequency response function (FRF) can be estimated by a Vector Auto-Regressive model (VAR model). The VAR simultaneous equations are set up in a time discrete state equations, which are consisted of measured points with q-time steps, in which q is the order of AR model. The classical modal testing approach based on fast Fourier transformation is used to compare the working procedure and the difference of results from both approaches. Finally we selected the identification of modal parameters for analysis of a numerical 3 dof numerical dynamic system and experiment of a cantilever beam as study cases. Results show that the VAR model has following advantages: (1)VAR model has better ability to filter out the noise. (2)The FRF curves from VAR model are more smooth. (3)The modal parameters determined from VAR model are in a more convenient way. (4)The calculated results from VAR model are more accurate.