A substructuring method for model updating and damage identification

Model updating of large-scale structures is time-consuming as the global system matrices need to be assembled continuously and the global eigensolutions and eigensensitivities are required in each iteration, even only a few elemental parameters need updating. In this paper, a substructuring approach is proposed to extract the substructural dynamic flexibility matrices from the measured modal properties of the global structure under the constraints of force compatibility and displacement compatibility. Thereafter the focused substructure is treated as an independent structure and updated directly using the traditional model updating method. It not only reduces the size of the analytical model involved in model updating but also decreases the uncertain parameters that need updating, thus resulting in a rapid convergence of the optimization process. Moreover, if a particular substructure needs updating the measurement can be focused on the local area of the interested substructure only and the requirement of measurement on the entire structure is avoided. A laboratory tested frame structure is employed to illustrate the effectiveness and accuracy of the proposed method.