Failure mechanism characterisation in composite materials using spectral analysis and the wavelet transform of acoustic emission signals

The applications for composite materials, especially in the automotive, chemical, petroleum and aeronautical industries, have been growing steadily in recent years due to their excellent properties, such as high specific mechanical properties and good corrosion resistance. Consequently, there has been a considerable increase in research toward the development of their structural properties, as well as the development of non-destructive inspection techniques for these materials.

This paper aims to evaluate the characterisation of failure mechanisms that occur in fibreglass reinforced polymeric matrix composites when subjected to tensile and flexural loads. The acoustic emission signals of failure mechanisms, emitted at the moment of breaking of test samples, are analysed in the frequency domain by the Fourier transform technique (spectral analysis), and in the time-frequency domain by the wavelet transform. Both techniques are evaluated in terms of the characterisation of failure mechanisms, such as: transverse matrix cracking (resin cracking), fibre/matrix debonding and delamination. The results obtained attest the efficiency of both techniques and are an encouragement for publication.