Fabrication and characterization of electrospun polyacrylonitrile carbonized fibers as strain gauges in composites for structural health monitoring applications

Abstract

This dissertation is aimed at developing new materials to be used as strain gauges in structural health monitoring (SHM) of composite aircraft structures. The unabated growth in air traffic has spurred increased demand in the aerospace industry to manufacture reduced-cost aircraft that are efficient to operate, friendly to the environment, and have an adequate level of safety. Due to their easy manufacturing process and high performance, carbon-based piezoresistive sensors, such as carbon nanotubes, graphite, and graphene, have been developed as alternatives to the traditional silicon/metal-based microelectromechanical system (MEMS), with applications ranging from industrial to medical fields. These sensors can be used in in-situ SHM industries and prosthesis applications because of their small size and high sensitivity to small forces. The detection of flaws and monitoring on a continuous and routine basis is the motive behind SHM devices. Nanomaterials play an remarkable role in the development of nanotechnology. Carbon nanofibers have high strength and stiffness as well as unique thermal and electrical properties. The primary precursor used for the bulk production of carbon nanofibers is polyacrylonitrile (PAN). The most promising technique for the synthesis of carbon nanofibers is electrospinning, with PAN as the main polymer precursor. This dissertation deals with the fabrication of PAN-derived fibers via electrospinning followed by stabilization and carbonization in order to remove all non-carboneous materials and ensure pure carbon fibers as the resulting material. Prepared nanofiber films were placed on pre-preg composites and cocured in a vacuum oven. The basic aim of this study was to fabricate lightweight and costeffective PAN-derived electrospun fibers for SHM applications of composites and test them for durability under different conditions.