Three-dimensional (3D) printing of fiber reinforced composites represents an enabling
technology that may bring toughness and specific strength to complex parts. Recently,
direct-write 3D printing has been offered as a promising route to manufacturing fiber
reinforced composites that show high specific strength. These approaches primarily
rely on the use of shear-alignment during the extrusion process to align fibers along
the printing direction. Shear alignment prevents fibers from being oriented along
principle stress directions of the final designed part. This paper describes a new
direct-write style 3D printing system that incorporates magnetic fields to actively
control the orientation of reinforcing fibers during the printing of fiber reinforced
composites. Such a manufacturing system is fraught with complications from the high
shear dominated alignment experienced by the fibers during extrusion to the slow magnetic
alignment dynamics of fibers in viscous media. Here we characterize these issues and
suggest effective operating windows in which magnetic alignment is a viable approach
to orienting reinforcing particles during direct-write 3D printing.
