Fractal dimension analysis for crack identification in beam structures

A new technique for crack identification in beam structures based on fractal dimension analysis is presented. The fundamental vibration mode of a cracked cantilever beam is analysed and both the location and size of the crack are estimated. The location of the crack is determined by the sudden changes in the spatial variation of the analysed response, while the size of the crack is related to the fractal dimension measure. The proposed prediction scheme was validated by experiments on cracked plexiglas beams. A noise test performed on simulated data proved the ability of the method to accurately identify cracks despite the presence of noise in the signal analysed. Based on the results obtained, a fractal dimension-based crack detector (FDCD) is developed, which can be effectively used in practical applications. Compared to existing methods for crack detection, the proposed FDCD scheme is attractive due to the simplicity of the evaluation of the fractal dimension measure and its robustness against noise.