Introduction

Laser powder bed fusion additive manufacturing (LPBF AM) is an additive manufacturing technology where a component is 3D printed by means of a layer-by-layer process. This kind of technology finds many applications in the aerospace and biomedical industry due to the superior surface finishing and mechanical properties of resulting components. Despite its success, a widespread application of LPBF AM in the industry is still burdened by the large uncertainty which characterizes the final artifacts. Mainly, we can indicate two main limitations of this technology:

1. Material defects (e.g., gas and keyhole porosity, lack-of-fusion defects) generated during the production process.
2. Residual stresses developed during production.

Goals

In this project, we mainly focus on numerical simulation of residual stresses and part deflection in LPBF AM processes. The objective of our work is twofold:

1. Estimate the influence of different process parameters (e.g., laser scan strategy, laser power and speed, etc…) on the residual stresses. 
2. Predict final distortions and residual stresses in the complete part.

To achieve these goals, we employ an immersed boundary approach namely the Finite Cell Method. This numerical technique allows us to treat complex geometries without a conform mesh generation process, which – especially for AM components – can be very challenging due to the generally complex shape of the artifacts.

Video 1: Von Mises stress evolution for a 10 layers LPBF AM process using the Finite Cell Method.

Video 2: Von Mises stress evolution and part deflection after support removal of a cantilever structure used to validate our part-scale immersed boundary model.

References

1. M. Carraturo, S. Kollmannsberger, A. Reali, F. Auricchio, E. Rank. “An immersed boundary approach for residual stress evaluation in selective laser melting processes”, submitted to Additive Manufacturing
2. M. Carraturo, B. Lane, H. Yeung et al. “Numerical Evaluation of Advanced Laser Control Strategies Influence on Residual Stresses for Laser Powder Bed Fusion Systems”, Integrating Materials and Manufacturing Innovation, 9, 435–445 (2020) – doi: 10.1007/s40192-020-00191-3
3. M. Carraturo, J. Jomo, S. Kollmannsberger, A. Reali, F. Auricchio, E. Rank. “Modeling and experimental validation of an immersed thermo-mechanical part-scale analysis for laser powder bed fusion processes”, Additive Manufacturing, 36, 101498 (2020) – doi: 10.1016/j.addma.2020.101498