Abstract
A comprehensive investigation is performed in this study to determine the electro-mechanical response for damage detection in novel multi-functional natural fiber composites under various mechanical loads. Both experiments and theoretical studies are performed in this research. A jute/epoxy composite system was fabricated by embedding multi-wall carbon nanotubes (MWCNTs) in the matrix and reinforcing short carbon fibers (CFs) between the jute laminates. The MWCNTs are embedded in the epoxy matrix using a combination of ultrasonication and shear mixing. The CFs are positioned along the through-thickness direction on the jute fiber laminates using UMass Dartmouth's patented "wet flocking" technique. The embedded MWCNTs in the matrix and reinforced CFs between the laminates generate a three-dimensional electrically conductive network in the composite. Four process variables such as weight percentage of MWCNTs (0.1 and 0.025), flock length (150μm and 350μm), flock density (500, 1000, 1500, and 2000 fibers/mm2), and two jute fiber orientations ((0-0-0-0)T and (0-90-0-90)T) are considered in this investigation for all experiments. The change in the electrical network of the composite associated with the mechanical loading is determined by the four-circumferential ring probes technique. In this study, first, a parametric study is performed to investigate the electrical resistivity of various composites with the above-listed process variables. To have a complete understanding of damage detection in multi-functional composites, the electro-mechanical response of the composites is then investigated under interlaminar shear and fracture loading conditions. Since composites have curved structures in real-life situations, an experimental study is also performed to determine the electro-bending response of curved composites under flexural loading. Moreover, a theoretical model was developed to investigate the electro-mechanical responses of carbon nanotubes embedded epoxy under shear loading conditions. A parametric study was performed, and the electrical response was compared with that of experimental findings.