A transient updated Lagrangian finite element formulation for bond formation in fused deposition modeling process

The bond formation among polymer filaments in the fused deposition modeling (FDM) determines the mechanical behavior of resultant parts and structures. A transient updated Lagrangian finite element formulation is proposed to simulate the bond formation among molten filaments in the FDM process with flexibility in dealing with complex geometry, boundary conditions and gravitational load. Qualitative and quantitative validation of the model is carried out by comparing with sintering experiments under both isothermal and non-isothermal conditions. The model is used to investigate the effects of initial configuration and boundary conditions and gravity on the bond formation in the FDM process. Results suggest that fidelity to configuration and boundary is crucial to the prediction of bond formation. Gravity imposes opposite influences on bonds along the vertical and horizontal direction and there is a trade-off between utilizing gravity to enhance the bond formation and keep dimensional accuracy of the printing process.