Finite Element activation strategy in the numerical simulation of Additive Manufacturing Processes

Additive Manufacturing (AM) is currently enjoying a tremendous boom. However, there is still a crucial lack of fundamental knowledge regarding AM. Hence, there is a high demand for the implementation of a model to accurately simulate an AM process. The complexity of such a simulation comes from multiple sources. Firstly, from the nature of the process. Indeed, it requires a large deformation thermo-mechanical simulation. Secondly, the modeling of the material law is complex. Lastly, the geometry of the process imposes a very fine discretization (layers can be as small as a few µm). This creates models that are computationally costly. Moreover, the process requires altering the geometry of the model during the simulation to model the addition of matter, which is a computational challenge by itself.
This work presents a first implementation of a three-dimensional thermal Finite Element Analysis (FEA) of AM in the fully implicit in-house Finite Element code “Metafor”. The main focus of the work is on mesh management. The method to activate elements and to activate and deactivate boundary conditions during a simulation is adapted from the element deletion algorithm (erosion method) implemented in Metafor in the scope of crack propagation.
The final model is compared against literature results, in particular to numerical and experimental results from a thermal experimental calibration of blown powder laser solid forming of Ti-6Al-4V. The model shows a reasonable agreement between the simulations.