Numerical simulation and experimental validation of deposited corners of any angle in direct ink writing

Abstract

Direct ink writing (DIW) belongs to material extrusion–based additive manufacturing (MEAM), and the molding quality of deposited corners has an impact on the geometrical quality of three-dimensional (3D) parts fabricated by DIW. To fully understand the DIW process and improve the geometrical quality of parts, numerical simulations have been widely used to model the DIW process. However, the previous research works for numerical simulation of deposited corners could only achieve the corner simulation under the condition of small angle and failed to realize corner simulation of any angle. Herein, an improved numerical simulation of deposited corners of any angle is proposed based on the use of volume of fluid (VOF) method and then the simulation is validated experimentally. In the numerical simulation, deposited corner is realized by constructing two calculation areas where two nozzle velocities with the corner angle are applied on the substrates of two calculation areas. The effectiveness of the proposed numerical model is validated through corner deposition experiments using a commercially available microcrystalline wax (MW)-based ink in a DIW 3D printer as the simulated corner angles fit experimental angles well and the maximum value of maximum distance deviation between simulated and experimental outlines (MDDSEO) is 1.06 ± 0.06 mm. It was observed that the MDDSEO of corners is larger than MDDSEO of straight filaments and decreases as corner angle increases. The current work demonstrates an effective approach for the prediction of the deposited corners of any angle in DIW based on numerical simulations.