Identification of Modal Parameters of Structural Systems with Severe Modal Interference

• Main Authors: Li-WenKuo, 郭力文
• Other Authors: Dar-Yun Chiang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/96967063027368653054

碩士 === 國立成功大學 === 航空太空工程學系 === 102 === In the process of identification of modal parameters, modal interference often affects the accuracy of the result of identification and even causes the problem of identifiability. Major causes of modal interferences include closely spaced modal frequencies, high damping ratios, and so on. Regarding closely spaced modes, the repeated modes are the most severe situation, which may lead to the problem of identifiability of modal parameters. This thesis explains why we need to use multiple references to identify repeated modes according to the formulation of frequency response function in modal analysis theory. We can determine the number of significant modes of a system by the Complex Mode Indicator Function, even when there are close modes or repeated modes. The Complex Mode Indication Function has been combined with the Enhanced Frequency Response Function to be a modal parameter estimation method. We can also use directly the data of singular values to identify modal parameters, and this method does not need to calculate the Enhanced Frequency Response Function.