On the Continuous Wavelet Transforms applied to discrete vibrational data for detecting open cracks in damaged beams

This paper deals with the detection of open cracks in beam structures that undergo transverse vibrations. The investigation is aimed at detecting the location of open cracks in damaged beams by minimizing measurement data and baseline information of the structure. The study is carried out by using the continuous wavelet transform (CWT). The application of this recent, but advanced, mathematical tool is initially presented through a theoretical background, which is believed to be valuable for bridging the gap between the CWT and previous existing techniques. It is shown how the possibility to efficiently identify localized damages by CWT comes up from the intrinsic capability of the wavelets to collect several mathematical tools in only one mathematical aspect: derivatives, convolution and appropriate smoothing of data are translated into the CWT. Simulations show how the redundancy of the CWT in the functional space is able to efficiently identify locations of open cracks in the presence of noisy or clean data. Indeed, the possibility to approach the problem by using different families of wavelets, for several available scales, allows a successful application of the characteristic microscopy of the wavelets. The technique may be promisingly applied to discrete vibrational data.