Nondestructive damage evaluation of plates using the multi-resolution analysis of two-dimensional Haar wavelet

A wavelet application to the vibration-based damage evaluation technique is introduced. The proposed method requires only a few of the lower mode shapes before and after a small damage event in order to detect, locate, and size damage on plate-like structures. The proposed method takes account for uncertainty in mass density, surrounding forces, foundation stiffness, etc. Based on a small damage assumption of a thin plate, the two-dimensional damage index (DI) equation is revealed within the context of elasticity. The singularity problem, which occurs in the resulting DI equation, is solved in the two-dimensional multi-resolution wavelet domain with the aid of the singular value decomposition technique. Finally, the desired damage measures are reconstructed from the one in the wavelet space by inverse wavelet transformation. The performance of the proposed method is compared with an existing damage detection method. Finally, an uncertainty analysis of the proposed method is provided.