A Study on the Effects of Damage Models and Wavelet Bases for Damage Identification and Calibration in Beams

Damage detection and calibration in beams by wavelet analysis involve some key factors such as the damage model, the choice of the wavelet function, the effects of windowing and the effects of masking due to the presence of noise during measurement. A numerical study has been performed in this paper addressing these issues for single and multispan beams with an open crack. The first natural modeshapes of single and multispan beams with an open crack have been simulated considering damage models of different levels of complexity and analyzed for different crack depth ratios and crack positions. Gaussian white noise has been synthetically introduced to the simulated modeshape and the effects of varying signal to noise ratio have been studied. The wavelet based damage identification technique has been found to be simple, efficient and independent of damage models and wavelet basis functions, once certain conditions regarding the modeshape and the wavelet bases are satisfied. The wavelet based damage calibration is found to be dependant on a number of factors including damage models and the basis function used in the analysis. A calibration based on curvatures is more sensitive than a modeshape based calibration of the extent of damage.