Modeling extrusion process and layer deformation in 3D concrete printing via smoothed particle hydrodynamics

We developed a computational framework to simulate the intricate processes of extrusion and layer deformation in 3D concrete printing (3DCP). A novel two-dimensional (2D) virtual printing scheme is proposed that enables direct prediction of cross-sectional shape, releasing simulations from the constraint of rectangular nozzles inherent in traditional 2D models. The proposed scheme accurately captures significant lateral deformation, previously ignored by conventional 2D models. It is noteworthy that, for the first time, the effect of time-dependent yield stress on layer deformation is considered by introducing the structuration rate. Further, to leverage advantages in avoiding mesh generation and additional interface tracking, a weakly compressible smoothed particle hydrodynamics (SPH) method incorporating the regularized Bingham model is equipped in the proposed framework. The simulated cross-sectional shapes exhibit excellent consistency with experimental results and outperform existing numerical results across various nozzle heights, printing velocities, and extrusion velocities. Our exploration of rheological parameters reveals that the final layer deformation is influenced by the yield stress, while its deformation rate is affected by the plastic viscosity. The proposed virtual printing framework emerges as a promising tool for enhancing predictability and efficiency in the printing process.