Matrix damage detection in laminated composite structures by Discrete Wavelet Transform

The present paper seeks to enhance the potential damage detention and location of the discrete wavelet transform (DWT) in a thin laminated composite damaged by a signal derived from vibration modes. The DWT-1D is used to spatially identify (x-y plane) the damage location. The matrix damage level occurs during the impulsive load application over the analyzed structure. The finite element used is a Serendipity-type element with a rectangular shape, eight nodes and five mechanical degrees-of-freedom per node, and is formulated by First-order shear Deformation Theory (FSDT). The dynamic equation of motion including internal damage is solved by the Newmark implicit integration method, considering small deformations. The results have demonstrated that discrete mother wavelets applied in dynamic modal signal processing are capable of detecting a small damage magnitude in the matrix level. The wavelet coefficients reached great amplitudes in the damaged area.