Damage Detection of Plane Strain/Stress Problems using Modal Data

Damages or cracks change the natural frequencies and the mode shapes of the structures. Therefore, the modal parameters could be used in damage detection or structural health monitoring techniques. Based on the knowledge of the authors, most researches in this field have been focused on one-dimensional problems, e.g. beams, trusses, columns, and frames. It seems that the main reason for the lack of comprehensive researches is the huge computational cost for two or three- dimensional problems involved with the finite-element modeling. In order to reduce the costs, two distinct techniques have been utilized here. Firstly, instead of using the genetic algorithm method, the particle swarm optimization (PSO) technique has been applied for finding the best solution. Secondly, instead of applying the fine meshes for calculation of the modal parameters in the finite- element modeling, the course meshes are used. In this paper, the combination of the frequencies and the mode shapes as an objective function has been applied in the optimization procedure for damage detection of two-dimensional plane stress type problems. For this purpose, the finite-element computer program has been developed in MATLAB environment for the required calculations. The results show that non- gradient-based optimization techniques such as GA and PSO have been successfully detected the existence, location and the intensities of the pre-defined damage scenarios.