The Effect of Shear-Induced Fiber Alignment on Viscosity for 3D Printing of Reinforced Polymers

Hoskins, Dylan
Ajinjeru, Christine
Kunc, Vlastimil
Lindahl, John
Nieto, Daniel Moreno
Duty, Chad
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University of Texas at Austin

Material printed with large scale additive manufacturing systems such as the Big Area Additive Manufacturing (BAAM) system experience a wide range of shear rates during the extrusion process. The shear rate can vary over five orders of magnitude as the material passes through the single screw extruder and is deposited onto previous layers. When fiber reinforced materials are deposited, the fibers can become highly aligned in the direction of flow due to the high shear stresses experienced as the material passes through the nozzle. Therefore, accurate analysis of the viscoelastic response of a polymer during extrusion should replicate these conditions as closely as possible. This study evaluates the effect of a pre-conditioning shear strain on the extrusion viscosity of carbon fiber reinforced acrylonitrile butadiene styrene (ABS).