Simulation of large-scale additive manufacturing process with a single-phase level set method: a process parameters study

In this work, a numerical method is presented in order to simulate the deposition of molten polymer bead onto a substrate and its cooling down in the large-scale extrusion-based additive manufacturing process. The polymer flow is treated as a single-phase flow with a free surface. This method reduces the computation time without loss of accuracy as polymer behavior significantly dominates air behavior. The governing equations of the fluid motion are solved with the finite element method on moving mesh, whereas the free surface is captured based on the level set method on another fixed mesh. Since the free surface is captured “implicitly” by the zero level of the level set function, coalescence between filaments is well defined and naturally performed. Numerical algorithm and implementation method are described in detail. This model provides detailed information on the cooling process and the bonding formation during the molten polymer deposition process. The effects of control parameters (nozzle velocity, flow rate and extrusion temperature, etc.) on the final deformed shapes of the printed parts are investigated. And finally, the numerical result from 2D simulations is compared to optical micro-graphs of the longitudinal cross-section of the printed sample, which shows good agreement between numerical and experimental results.