Wavelet-based AE characterization of composite materials

This paper addresses an application of recently developed wavelet-based sig nal processing technique on a composite fracture behavior study. Here, the wavelet methodology is introduced, and a complete procedure of wavelet-base d acoustic emission (AE) analysis methods developed by the author are demon strated. In this research, the AE signals from glass fiber reinforced (GFR) composites are collected during the standard quasi-static tensile testing and transformed by the Daubechies discrete wavelets using the programs deve loped by the author. Based on AE tests, the fracture behaviors are studied for the material. In the study of GFR composite fracture behavior, classica l linear fracture mechanics method is used for comparison. The exponential constant m value used to determine the relationship between stress and stre ss intensity factor are compared relative to the classical fracture mechani cs and the AE techniques. In order to demonstrate the advantage of the wave let-based AE techniques, the conventional AE analysis is also provided side -by-side for comparison. The results verify that the wavelet-based method b etter approximates residual strength relative to the classical AE technique s. In this paper, the results of the wavelet-based AE analysis of glass fiber composites are presented. The results indicate that wavelets-based signal p rocessing is an efficient tool in the analysis and the transformation of AE signals. (C) 2000 Elsevier Science Ltd. All rights reserved.