CFD Modelling of Mortar Extrusion and Path Planning Strategy at the Corner for 3D Concrete Printing

Computational Fluid Dynamics (CFD) modelling has become an important tool for accelerating different costly and time-consuming processes for 3D concrete printing. In this study, a CFD model is developed to simulate the mortar extrusion and deposition flow in order to investigate the path planning at the corner. The mortar is characterized by a viscoplastic Bingham fluid. The printhead moves according to a prescribed speed to print trajectory with a turn of 90° angle. The model solves the Navier Stokes equations and uses the volume of fluid (VOF) technique. This work investigates the effects of changing printhead direction in the geometrical conformity and the process precision. The direction change is carried out by the acceleration steps and jerk. A smoothing factor is provided to smooth the toolpath. Several simulations were performed by varying the smoothing factor and jerk. Overfill has occurred at the sharp corner when applying a jerk due to the constant extrusion rate. Dependance between the acceleration steps, the acceleration time limit and the jerk has been found.