A damage identification approach for plate structures based on frequency measurements

Plates play an important part in various structures. In this study, a damage detection method is proposed to identify damages in plate-type structures, which is based on frequency contour lines method. Different from damage identification using natural frequency for beam-type structures, the damage identification of plate-type structures is more complex: boundaries are varied and damage parameters are more diversified. By using variable separation, the identification problem is divided into a series of two-parameter problems. Based on the Reissner-Mindlin plate element, the frequency database of a damaged plate is obtained as an input of the forward problem. And as an inverse problem, the measured natural frequencies are used as inputs of the database. Then the intersections of the three frequency contour lines are obtained, which indicates the level of damage and location. A range of numerical examples are given to verify the validity of the proposed algorithm. The determined levels of damage and locations by the proposed method are in good agreement with the actual conditions.