Macroscopic thermal finite element modeling of additive metal manufacturing by selective laser melting process

Abstract

A 3D finite element model is developed to study heat exchange during metal selective laser melting (SLM). The approach is conducted on the scale of the part to be formed, using a level set framework to track the interface between the constructed workpiece and non-melted powder, and interface between the gas domain and the successive powder bed layers. In order to keep sustainable the computational efficiency, the powder bed deposition and the energy input are simplified by the scale of an entire layer or fractions of each layer. Layer fractions are identified directly from a description of the global laser scan plan of the part to be built. Each fraction is heated during a time interval corresponding to the exposure time to the laser beam, and then cooled down during a time interval equal to the scan time for the considered layer fraction. The global heat transfer through the part under additive construction and through the powder material non-exposed to the laser beam is simulated. To reduce the computational cost, a refining and de-refining mesh adaptation is carried out with a conform mesh strategy. Mesh sensitivity tests and validation of energy conservation are discussed. The proposed model is able to predict the temperature distribution and evolution in the constructed workpiece and non-melted powder during the SLM process at the macroscale, for parts of complex geometry.Application is shown for a nickel based alloy (IN718), but the numerical model can be easily extended to other materials by using their data sets.

Thermal analysis of the fused filament fabrication printing process: Experimental and numerical investigations

“…Thermal numerical computations are performed based on the model developed by Zhang et al [24] and implemented in the C++ library CimLib. Initially developed for the selec- tive laser melting process, the numerical procedure is thus modified to match with the FFF process.…”

Numerical study of the impact of vaporisation on melt pool dynamics in Laser Powder Bed Fusion - Application to IN718 and Ti–6Al–4V

“…Roberts et al [18] and Marion et al [19] use a heat source model considering the local absorption of laser energy in Ti-6Al-4V alloy. Finally, Zhang et al [20] present an original and complex finite element model (FEM) applied to IN718 alloy. Both unmelted powder and surrounding gas domains are meshed.…”

A Review of Model Inaccuracy and Parameter Uncertainty in Laser Powder Bed Fusion Models and Simulations

“…In this approach, the powder bed and substrate are discretized into finite number of elements to solve heat transfer governing equations and boundary conditions. Considering (a) convection heat loss due to surrounding gas, (b) thermal radiation loss on the free surface, (c) temperature-dependent material properties, and (d) the effect of latent heat of fusion during phase changes, certainly improve the predictive accuracy of FEM-based thermal models [50,57,74–77]. The common assumptions of FEM thermal models are that the powder bed is considered to be a continuum body instead of randomly distributed particles, and the dynamics of the melt pool, including fluid flow and convection of the melt pool due to surface tension, are neglected.…”