Layer-to-Layer Melt Pool Control in Laser Powder Bed Fusion

Additive manufacturing (AM) processes are flexible and efficient technologies for producing complex geometries. However, ensuring reliability and repeatability is challenging due to the complex physics and various sources of uncertainty in the process. In this work, we investigate closed-loop control of the melt pool dimensions in a 2-D laser powder bed fusion (LPBF) process. We propose a trajectory optimization-based layer-to- layer (L2L) controller based on a linear parameter-varying (LPV) model that adjusts the laser power input to the next layer to track a desired melt pool depth and validate our controller by placing it in closed-loop high-fidelity multilayer smoothed particle hydrodynamics simulator of the 2-D LPBF process. Detailed numerical case studies demonstrate successful regulation of the melt pool depth on brick and overhang geometries and provide first of its kind results on the effectiveness of L2L input optimization for the LPBF process as well as detailed insight into the physics of the controlled process. Computational complexity and process performance results illustrate the method's effectiveness and provide an outlook for its implementation onto real systems.