High-fidelity finite element modelling of multi-layer 3D printing with complex toolpaths

Extrusion-based additive manufacturing produces objects by depositing material layer-by-layer, yet predicting geometry and structural integrity remains challenging due to complex material rheology, nozzle dynamics, and toolpath dependence. High-fidelity models can capture extrusion dynamics and the true layer shape, but have traditionally been limited to simple geometries and few layers. This work extends these simulations to multi-layer structures with complex geometries involving overhangs and twists, while automatically managing intricate G-codes. A Particle Finite Element Method (PFEM) framework is employed to handle free-surface evolution, large deformations, and the time-dependent viscoplastic behaviour of the extruded material. Two novel strategies for G-code optimization - arc-based toolpath resampling and adaptive time-step cutting - are also proposed to ensure accurate nozzle motion resolution while maintaining computationally efficient simulation time steps. Applied to virtual printing of complex objects, the framework shows when material and geometry jointly determine stability and shape fidelity, enabling optimization of additive manufacturing across polymers, bioprinting inks, clays, and cementitious materials.