Nanoscale Design of Interfacial Kinematics in Composite Manufacturing

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The ubiquitous usage of polymer matrix composites in aerospace, automotive, and other applications necessitates both a fundamental understanding of the manufacturing process and novel design strategies to engineer their behavior. Ply interfaces are known to play a crucial role in composite manufacturing. Movement of ply interfaces during curing can lead to manufacturing defects that affect the composite structure performance and have been a limiting factor in several applications, resulting in delays and redesigns of products like aircraft and civil infrastructure. This grant aims at understanding the evolution and movement of composite interfaces during their manufacturing through the development of a novel in-situ characterization approach using digital image correlation (DIC). In addition, nanoscale interfacial components such as zinc oxide (ZnO) nanowires will be utilized to mechanically alter the interfacial behavior during curing. Multiscale computational modeling will complement experimental investigations. The outcome of this research will lead to novel diagnostics that reduce processing-induced defects and addresses the current manufacturing needs of the commercial and defense industries. The educational impacts of the project involve the development of a vertically integrated pathway for engaging students in materials engineering, all the way from K-12 to graduate school.This research will elucidate the role of interfacial kinematics and energetics in the evolution of inter-ply interfaces in composite structures during manufacturing. The research team will develop a novel experimental method for in-situ characterization of surface and interface deformations during composite processing, utilizing a customized commercial composite autoclave with a digital image correlation system. The surface strain and displacement measurements will be combined with ex-situ X-ray tomography and thermal characterization to map the interfacial thermomechanical response as a function of design and processing parameters. Additionally, the interfacial behavior will be engineered through the rapid and controlled growth of ZnO nanowires on carbon fibers to create a nanoscale interfacial component that increases the fiber bending resistance and creates an interlocking effect at the interfaces to mitigate defects propagation. The experimental research will be complemented by molecular dynamics simulations of the sliding of amorphous polymer interfaces and mesoscale simulation of flow in porous media. This comprehensive approach of in-situ characterization, interface design, and modeling will lead to a fundamental understanding of the ply movement during composite manufacturing and development of methods to reduce the occurrence of processing-induced defects.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.