Cluster analysis of acoustic emission signals for bending damage mechanism of flax fiber reinforced composites under hydrothermal aging

Despite the eco-friendly and lightweight features, natural fiber reinforced composites (NFRCs) are more susceptible under hydrothermal conditions than artificial synthesis fibers reinforced composites. Cluster analysis on damage evolution of hydrothermal aged NFRCs by using acoustic emission techniques and machine learning also remains scare. To figure out these challenges, unidirectional flax fiber reinforced composites (FFRCs) were prepared and submerge into distilled water at three different temperatures to systematically study the influence and damage mechanism under hydrothermal aging by acoustic emission (AE). After hydrothermal aging for 60 days, AE signals revealed that the FFRCs were more likely to cause defects in the early loading stage at the higher temperature. Cluster analysis showed an increase in the proportion of delamination during the process of failure. The proportion of fiber breakage AE signals with higher PF also increased. Microscope view proved the bending damage behavior of FFRCs after hydrothermal aging.