Acoustic emission wavelet transform on adhesively bonded single-lap joints of composite laminate during tensile test

Abstract

Acoustic emission detection in composites is complicated in comparison with metallic structures due to the complex nature of acoustic emission wavelet transform in anisotropic materials. In this study, the adhesively bonded single-lap joints with zero-degree orientation are used to trigger different failure mechanisms when subjected to tensile test with acoustic emission monitoring. Acoustic emission signals which are studied for damage characterization are obtained during tensile tests. The range of peak frequency with time, pertaining to the failure mode in adhesively bonded single-lap joints has been identified using wavelet transform. Signals and their characteristics representing different failure modes are identified and validated using wavelet transform analysis. Continuous wavelet transform is then applied to identify the frequency range and time history for failure modes in each signal. The fractured surface area of the bonded single-lap joint specimen was examined directly using a scanning electron microscope and also identified the failure mechanism of bonded single-lap joints. The results obtained from acoustic emission technique are compared with scanning electron microscope results, to find the evidence of predicted damage. This study of the frequency content of each test using continuous wavelet transform is then performed and the classification of several failure modes is identified.