A two-step approach for damage Identification in plates

This paper presents a two-step approach based on modal strain energy and response sensitivity analysis to identify the local damages in isotropic plates with moderate thickness. The first step focuses on detection of damage location. The local damage is simulated by a reduction in the elemental Young's modulus of the plate. It is determined from the modal strain energy change ratio approach. A method to weaken the "vicinity effect" is proposed to reduce the false alarms in the localization of damage. In the second step, an approach based on response sensitivity-based finite element model updating is used to further identify the locations and extents of the local damages in time domain. The identified results are obtained iteratively with Tikhonov regularization using the measured structural dynamic responses. Two numerical examples are investigated to illustrate the correctness and efficiency of the proposed method. Both single and multiple damages can be identified successfully and the effect of measurement noise on the identification results is investigated. Good identified results can be obtained from the short time histories of a few number of measurement points.