A part-level simulation method considering thermal-mechanical contact between multiple filaments for material extrusion processes

Part-level thermal-mechanical simulation with filament resolution is currently a significant challenge for material extrusion processes. This paper proposed a novel method to achieve part-level and high-fidelity simulation for such processes, where the physical behaviours of heat transfer, viscoelasticity, dynamics, and contact are comprehensively considered. This method integrates a sophisticated thermal-mechanical contact model with a thermo-viscoelastic dynamic model. The kinematic and dynamic behaviours of the filaments were described based on the theory of discrete differential geometry, and the contact force and heat transfer between multiple filaments were modelled by using a newly defined contact element with spring-dashpot forces and heat conduction. The contact parameters were determined, and the accuracy was validated through contact experiments. The contact reheating and temperature distribution were quantified, and the effects of the printing parameters on the contact heat transfer and deformation were examined. Several part-level cases were simulated to demonstrate its capability in industrial applications.