Nondestructive damage detection algorithms for 2D plates

The objective of this paper is to develop appropriate nondestructive damage detection algorithms for two-dimensional plates. Two methods, one using the local compliance and the other using local modal strain energy, are presented and compared in this paper. The compliance method is derived simply from the governing differential equations of motion presented in the classical plate theory. The second method is developed from expressions for the elastic strain energy of a plate. A damage index, used to indicate local damage, is defined and expressed in terms of modal displacements that are obtained numerically from mode shapes of the undamaged and the damaged structures. The possible damage locations in the structure are determined by the application of damage indicators according to previously developed decision rules. The damage indices, which are obtained for each mode, are transformed to probability space and superposed as weighted general means (WGM). In the WGM, the fraction of modal energy for the element is used as the weight of each mode. Each of the two methods is demonstrated by using a numerical example of a simply supported plate with simulated damage. Finally, the relative performances of the two methods are compared.