Zoom Link: https://kaust.zoom.us/j/99407370904

Abstract

Polymer extrusion/deposition is perhaps the most popular additive manufacturing technology as it offers significant design flexibility with extensive material options at a low cost. While the introduction of chopped carbon fibers into the polymer matrix improves thermo-mechanical properties, fiber inclusions appear to be instigators for micro void nucleation in the bead microstructure, leading to inferior part performance. This presentation considers the presence of carbon fiber and its influence on micro void formation (process) during polymer composite extrusion/deposition Large Area Additive Manufacturing (LAAM). Micro CT is used to characterize the microstructure within printed carbon fiber ABS (CF-ABS) beads where correlation between fiber alignment and void formation (property) is explored for the pellet feed stock, freely extruded strand, deposited bead, and roller compacted bead. Next, fiber tip pressure within the extrusion/deposition polymer composite melt flow is evaluated with a custom multiscale finite element modeling procedure which identifies a fundamental mechanism for potential void nucleation during processing. Finally, a finite element study and fracture toughness testing are presented which highlight the dependence of interlayer bead adhesion (performance) on fiber orientation and void content.

Biography

Dr. Douglas E. Smith is a Professor of Mechanical Engineering at Baylor University and a Fellow of ASME. He holds a PhD ME from University of Illinois at Champaign-Urbana, a MSME from Binghamton University, and a BSME from Washington University and Illinois College. His research focuses on polymer composites and polymer melt flow modeling, simulation and testing where recent applications include extrusion/deposition additive manufacturing and laminated carbon fiber polymer composites. Of particular interest is the development of microstructural features in short fiber polymer composites. Dr. Smith is an NSF CAREER Award recipient, and his research has been supported by NSF, US Dept of Ed., ONR, AFRL, ORNL, and industry partners. He was named a Baylor Outstanding Professor in 2023.