Additive manufacturing of 3D structures with non-Newtonian highly viscous fluids: Finite element modeling and experimental validation

Additive manufacturing (AM) of highly viscous materials, e.g., polysiloxane (silicone) has gained attention in academia and different industries, specifically the medical and healthcare sectors. Different AM processes including micro-syringe nozzle dispensing systems have demonstrated promising results in the deposition of highly viscous materials. This contact-based 3D printing system has drawbacks such as overfilling of material at locations where there is a change in the direction of the trajectory, thereby reducing the printing quality. Modeling the continuous flow of a highly viscous polysiloxane in the nozzle dispensing AM system using finite element analysis will be the first step to solve this overfilling phenomenon. The results of simulation can be used to predict the required variation in the value of pressure before the nozzle reaches a corner. The level-set method is employed for this simulation, and the results are validated by comparing the flow profile and geometrical parameters of the model with those of the experimental trials of the dispensing of polysiloxane. Comparisons show that the model is able to predict the location of the droplet before it reaches the substrate, as well as the height of the droplet generated on the substrate accurately. To predict the width of the droplet, adjustment factors need to be considered in calculations based on the value of the pressure. (C) 2016 Elsevier B.V. All rights reserved.