Finite element modelling of fully-coupled flow/fiber-orientation effects in polymer composite deposition additive manufacturing nozzle-extrudate flow

Abstract This paper presents a Finite Element Method (FEM) based algorithm to simulate the mutually dependent effects between non-Newtonian polymer melt flow and fiber orientation in Polymer Composite Deposition Additive Manufacturing (PCDAM). The computational approach is employed to analyze an axisymmetric flow with a free surface that defines the melt extrudate. The non-Newtonian power law model is applied to quantify the shear thinning rheological behavior of the polymer flow. The fiber orientation state of the composite melt is simulated using the Advani-Tucker orientation tensor approach, and a streamline-based remeshing technique is applied to compute die swell of the free extrudate. The non-linear FEM system is solved with the Newton Raphson iteration method. Computed results are compared to those obtained using a flow-fiber one way coupling simulation, where it is shown that the magnitude of flow field along the direction of extrusion, as well as the fiber alignment in the flow direction, both increase when full coupling is used. In addition, the extrudate swell ratio solved by the fully-coupled scheme reduces by roughly a factor of ~2 × as compared to the weakly-coupled flow solution.