Eigenparameter perturbation method for structural damage detection

A methodology is developed for detecting single structural damage using the perturbation of eigenparameters. By Taylor's series expansion, the relationship between the eigenparameters perturbation and the damage parameters variations is established. The Jacobian matrix involved can be obtained by a sensitivity method or a perturbation method in different situations. The sensitivity method is demonstrated in damage detection of a cantilever beam structure. While the perturbation method is used in damage detection of a multi-bay truss. For evaluation of the capability of the algorithm, the method is applied on an experimental multi-bay truss model. The damage detection procedure is divided into two parts. The location of the damage is estimated by observing the region with the largest stiffness reduction. Then the extent of the damage is estimated by performing iterations of the damaged component. Using the first few fundamental eigenvectors, the extend of the damage converges rapidly to the exact value within several iterations.