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Identification of damage modes in polypropylene/epoxy composites by using principal component analysis on AE signals extracted from Mode I delamination

Acoustic emission (AE) can be used to distinguish different types of damage occurring in composite materials. The main problem associated with data analysis is the classification of different AE sources. The target of cluster analysis is to classify a set of data into several clusters that reflect the internal structure of the data. In this study, a procedure for the evaluation of delamination mechanism in ultra-high molecular weight polypropylene/epoxy (UHMWPP/epoxy) composite specimen with different configurations based on the analysis of AE signals is presented. Epoxy resin, UHMWPP fibre bundle and UHMWPP/epoxy specimens, subjected to tensile test and Mode I delamination, were investigated. It is shown that the principal component analysis is an effective tool for identifying damage modes such as matrix cracking, fibre–matrix debonding, fibre breakage and fibre pull-out in the UHMWPP/epoxy composites. The presence of damage modes in UHMWPP/epoxy composites was proven with scanning electron microscopy images.