Session: 03-04-02: Emerging Materials Technology

Paper Number: 121636

121636 - Nanomechanical Characterization of the Interface Properties of Hybrid Carbon Fibers for Multifunctional Applications 

The carbon fiber/epoxy interface is of great importance in composite design due to its load transfer mechanisms from the weak epoxy to the stronger fiber. Improving the strength of that interface reduces the risk of failure at the interface and improves the load transfer to the fiber. In this study we used insitu growth of two types of nano-species ZnO nanowires and nickel based metal organic fibers, on carbon fibers to improve the interfaces. SEM characterization indicates uniform growth of the nanomaterials on fiber surfaces. We employ a low temperature hydrothermal process that does not degrade the fibers to grow these nanomaterials on fiber tows.

The interfacial mechanics of the enhanced fibers are evaluated using nanoindentation studies. Composite samples with aeroepoxy matrix and vertically aligned fibers are fabricated for this purpose. Bruker TI-980 TriboIndenter with Berkovich indenter is used to perform single-fiber push-in tests to analyze the interfacial behavior. The load-displacement curves of these push-in tests denote a clear nonlinearity where debonding occurs, and the debonding loads are used to calculate interfacial shear stress. We observe a 15-20% improvement in interfacial strength with the fiber modification.  Furthermore, we analyze the interface modification through a hydrodynamics perspective, developing a model to look at resin penetration through the nano-species. Using this model, we find that the nano-species improves the absorption of resin into the interface region, and that the absorption timescale is significantly less than the curing timescale for the epoxy. Essentially, due to the increased surface energies of the nano-species, the nano-species improves the wetting of the epoxy onto the fibers at a faster rate than with neat fibers. In summary, our findings lead us to the conclusion that the growth of these nano-species enhances the interfacial properties of the carbon fibers and opens up promising possibilities for multifunctional applications by harnessing the properties of the nanomaterials.

Presenting Author: Sirish Namilae Embry-Riddle Aeronautical University

Presenting Author Biography: Sirish Namilae is a tenured Professor and Ph.D. program coordinator in the Aerospace Engineering Department at the Embry-Riddle Aeronautical University. He obtained his MS in Materials Science from the Indian Institute of Science, and a Ph.D in Mechanical Engineering from Florida State University in 2004. He joined the Aerospace Engineering Department at Embry-Riddle in 2014 after ten years of experience in industry (Boeing) and national lab. (ORNL). At ERAU, Dr. Namilae leads the Advanced Materials and Mechanics Group and directs the Composites lab. His research has focused on the areas of composite materials and complex systems & multiscale modeling. He has authored about 100 Journal and Conference publications in these research areas and has advised over thirty graduate students (MS and PhD Thesis).