The size, location and orientation of the crack are identified by finding the intersection of the surfaces that correspond to the natural frequencies' ratios of the lower vertical and horizontal modes. One of the advantages of the proposed approach is that, unlike other vibration-based damage identification procedures, it does not use a priori accurate knowledge of the angular frequencies of the uncracked structure and its material properties. Only the Frequency Responses Functions and natural frequencies of the cracked structure are needed to identify the crack parameters (i.e. the non-dimensional crack depth, the crack location and the crack orientation).

It is demonstrated that damage identification methodology, called the Frequencies' Ratio Surfaces Intersection method (FRSI-method), can be used for the detection of the crack size, location and orientation with satisfactory precision, even if noise level has been added to the simulations. KW - damage detection KW - vibration KW - frequencies and antiresonances KW - identification of the crack size KW - location and orientation KW - uncertainties DO - 10.3970/sdhm.2007.003.133