Comparisons between modal-parameter-based and flexibility-based damage identification methods

Modal parameters and modal flexibility obtained from the modal experiment have been used for damage identification in frequency domain. These two methods are compared in this paper numerically and experimentally. The optimization objective function of the former method is a weighted function of the frequency and mode shape residues, in which different weights can be assigned to the frequencies and mode shapes so that their degrees of accuracy can be taken into account. The optimization objective function of the latter method is the modal flexibility residue. Based on the same modal data, the two methods are compared from different aspects, including the damage configurations and uncertainties in the modal data. Results show that using the modal parameters directly can detect damage more accurately and reliably than using the modal flexibility.