Anisotropic Viscous Flow Simulation for Fiber Orientation Analysis
The anisotropic viscosity introduced by the presence of fibers in a molten polymer matrix is often neglected in flow analyses for determining resulting fiber orientation in molding processes. While this simplification may be appropriate in short fiber systems at low fiber volume fractions, long fiber systems at high fiber volume fractions exhibit behavior which cannot be captured in an uncoupled analysis. Capabilities for 3D simulation of anisotropic viscous flow with fiber orientation kinematics were developed using commercial finite elements methods and user material models. Fiber orientations are modeled using sets of test fibers allowing for a complete description of fiber state required to form an orientation averaged, anisotropic viscous stiffness matrix, and fiber orientation evolution is modeled as affine motion with the bulk material. Compression molding of a center gated disk is treated as a test problem to investigate coupled flow behavior. Initial orientation states are varied and resulting flow behaviors are compared. The resulting effects of coupling demonstrate behavior which cannot be captured in uncoupled models.
Author: Anthony Favaloro
Conference: SAMPE Seattle 2017