Speaker
Description
The Directed Energy Deposition (DED), a metal additive manufacturing process, opens up new possibilities for the manufacturing of multi-material structures by controlling the feedstock composition fused by the laser and mixed in the melt pool. Defect-free fabrications and control of the layers' composition however require the complex selection and fine-tuning of a large process parameter set. Indeed it is often necessary to modify the parameters depending on the melt pool’s target composition, while also taking into account the mixing with the previous layer.
Here we present a 3D finite element model of the melt pool aimed at fast prediction of the dimensions and composition field of the layer. The influence of track overlap on the melt pool geometry and composition is taken into account by updating the upstream boundary conditions with the composition and free-surface shape of the calculated molten track. The eddy viscosity originating from turbulence is approximated by a simple formula validated by a more complete v²-f RANS model. Microstructural and elemental analysis of a bi-metallic interface created by LPD is used to assess the validity of the model through SEM and EDS characterizations.
Simulation results illustrate that the fluid flow induced by surface tension gradients plays a critical role in the final shape and composition of the tracks and thus cannot be ignored. Comparison between simulation and experiments is satisfactory. A sensitivity study highlights the key parameters and material properties which affect the melt pool and must be set or known accurately enough to allow predictive simulations and parametric optimization, the latter being made possible by the short computation time.
Keywords: characterization, modelling, simulation, dissimilar materials, Additive Manufacturing, DED
| Speaker Country | France |
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