Análise espectral de ondaletas aplicadas à sinais de emissão acústica provenientes de deformação

Abstract

In the time series analysis in the frequency domain is traditionally done by studying the power spectrum obtained by Fourier transform. The Fourier theorem states that one can express a periodic function as a sum of a constant and a determos series of sines and cosines, where the frequencies associated with these functions are integer multiples (harmonics) of the fundamental frequency. The wavelet analysis can reveal aspects of missing data in other signal analysis techniques, aspects such as trends, breakdown points, discontinuities in higher derivatives, and self-similarity. In addition, it provides a different view of data than those presented by traditional techniques, wavelet analysis can often compress or remove the noise of a signal without appreciable degradation. In this context, acoustic emission signals from the uniaxial tensile deformation in polyethylene samples were analyzed and characterized, resulting in a clear distinction between the signals from the elastic and plastic deformation regimes.