Modeling of Metal Powders and Powder Spreading Processes
Powder spreading
Powder spreading is the first step in the LPBF process and thus has fundamental impact on the subsequent melting. Understanding the behavior and underlying physical properties of metal powders is critical to improve the powder deposition process and ultimately rate and quality of the LPBF process. Our in-house DEM-FEM research code is pushing the state-of-the-art on modeling powder, (flexible) tools and novel processing techniques.
Our computational work is complemented by a close collaboration with the Mechanosynthesis Group at MIT, where powder spreading approaches are researched experimentally with custom-build machines and novel metrology instrumentation. Through this collaboration, we calibrate our computational model for specific materials such as Ti-6Al-4V and verify simulation results with experiments.
The project incorporates mathematical modeling, development and implementation of adequate algorithms, validation of simulation methods with experiments, and coupled numerical simulation of powder deposition processes. A coupled DEM-FEM framework was developed, with a focus on allowing to simulate large systems (order of 10e6 particles) in combination with compliant structures (e.g., silicone spreading implements). As a result of this project, a new understanding of the impact of powder cohesion and different spreading parameters and strategies has been established.
Powder inclusions for controllable dissipation
Particle dampers, consisting of loose particles inside an enclosure, are a well-known means to dissipate unwanted oscillations. Conventional particle dampers are usually external devices that are attached to structural components. However, powder bed fusion additive manufacturing processes allow for a direct integration of particle inclusions into the resulting part without the need for an external device. The required particles for the damper are already present as loose particles in the powder layer during the manufacturing process. Ultimately, the goal is to control the dissipation behavior of the printed part.
To this end, a two-way coupled discrete element - finite element model is employed. This allows to describe the interaction between the oscillating deformable structure and the enclosed powder particles. Friction and inelastic impacts between the powder particles and the walls of the enclosure dissipate energy such that vibrations are reduced.
Publications
Please find publications on this topic here.