Numerical modelling of fluid and solid thermomechanics in additive manufacturing by powder-bed fusion: Continuum and level set formulation applied to track- and part-scale simulations

The thermomechanical analysis of powder-bed fusion using a laser beam is simulated in both meso- and macroscales within a framework combining continuum assumption and level-set formulation. The mesoscale simulation focuses on laser interaction with the powder bed, and on subsequent melting and solidification. Modelling is conducted at the scale of material deposition, in which powder-bed fusion, hydrodynamics in the melt pool, and thermal stress are simulated. The macroscale model focuses on part construction and post-deposition. During construction, by contrast with the mesoscale approach, the fluid flow in the fusion zone is ignored and material addition is simplified by modelling it at the scale of entire layers, or fractions of layers. The modelling of the energy input is adapted accordingly. This thermomechanical model addresses heat exchange, residual stress, and distortion at the part's scale. In both approaches, adaptive remeshing is applied, providing a good compromise between the needs to provide accurate prediction and maintaining sustainable computation times.