Effect of electrospun PA66 nanofibrous mat thickness on mode-II fracture toughness using acoustic emission (AE) with data clustering technique

Abstract

Considering the importance of improving the fracture toughness of composite laminates, in this research, by embedding electrospun nanofibers of polyamide 66 between the layers, the fracture toughness of prepared samples was evaluated in Mode-II loading and compared to the reference state. It was demonstrated that adding polyamide 66 nanofibers of two distinct thicknesses, 110 and 140 μm increased the fracture toughness in mode-II by 84 % and 47 %, respectively. Thus, there is an optimum value for thickness of nanofibers to have maximum enhancement of fracture toughness. Additionally, the acoustic emission method was used to examine the key features that increased fracture toughness. Using acoustic emission features and hierarchical model clustering, it was shown that fiber/matrix debonding is the primary damage mechanism lowering the mode-II fracture toughness. Macro pictures and SEM micrographs were used to observe the failure mechanisms on the sample surfaces.