Process-informed smooth particle hydrodynamics-finite element (SPH-FE) simulation of 3D concrete printing: from flow behaviour to structural failure

In three-dimensional concrete printing (3DCP), accurately simulating structural failure while maintaining geometric fidelity remains challenging due to complex interactions among material flow, layer build-up, and early-age mechanical response. This study develops three novel numerical models to address these challenges. Among them, a coupled Smooth Particle Hydrodynamics-Finite Element (SPH-FE) model is developed to fully integrate fluid flow, solid mechanics, and fluid–structure interaction (FSI), with a custom Python-based script converting SPH-derived geometries into FE inputs. Two additional novel FE models, a simplified model based on idealised assumptions and a geometry-refined sophisticated model, are developed to provide complementary strategies with varying levels of fidelity and efficiency. An experimental-numerical framework is established by integrating the three models with material and printing tests. Rheological, uniaxial compression, and direct shear tests are conducted to characterise the time-dependent behaviour of fresh mortar. Wall structures and five-layer specimens are printed to observe failure and extract realistic layer geometries. Results show that the SPH-FE model enables realistic simulation of layer shape, extrusion forces, and nozzle height evolution, thereby improving accuracy in capturing geometric evolution and failure. The sophisticated FE model improves accuracy over the simplified model but lacks process coupling. These findings highlight the value of process-informed modelling for improving geometric control, enhancing failure prediction, and advancing automation in building engineering through 3DCP.