Improvement of damage identification ability in composite structures using 2D undecimated fractional wavelet transform

Damage assessment problem in composite structures gained a great importance in recent decades due to the more and more strict demands to the structural safety of aircraft elements. One of the intensively developed methodologies of damage assessment is an approach based on modal analysis and further processing of modal shapes using the wavelet-based methods. During the analysis using discrete wavelet transform the dimensions of spatial domain reduces twice in each direction, which lowers the resolution of resulted patterns. Considering the advantages of application of fractional wavelet transform with fractional B-spline wavelets the algorithm was modified by excluding the decimation process during wavelet-based decomposition. Such a modification allows for obtaining the resulted pattern after decomposition with the same dimensions as an input signal, which improves the localization performance of damages. The advantages of the proposed approach was presented on several examples.