Directed Energy Deposition (DED) is an additive manufacturing process where metal wire or powder is combined with an energy source to deposit material onto a part directly. Rather than spreading a layer of metal powder across a surface and scanning the part's profile with a laser to build up a part surrounded by unmelted powder, only the desired part is built in a DED process, with no surrounding leftover powder. The DED process is much less expensive than LPBF but less precise. It is widely used to repair, or add extra material to, existing parts.
Important: Ansys provides two methods of DED process simulation. The first is a simplified approach in which super layers representing several actual welded layers are lumped together using the birth-and-death technique just as in an LPBF simulation. Most of the steps are the same, with special considerations as described in this section.
The second approach is a more detailed and accurate representation in which the path of each deposition weld track is "followed" using element clusters that are made alive using the birth-and-death technique. This approach uses the DED Process Add-on. Refer to the dedicated user's guide for details.
Simulation of a DED process using the simplified approach is almost the same as for an LPBF process, except that the convection of heat from the part as it is being built must be accounted for differently. Specifically, convection to the surrounding gas in the chamber is applied to all sides of the build as it is building. (This differs from an LPBF simulation, in which the convection is applied only to the top of a newly deposited layer.) A DED simulation uses only the gas convection properties of the build settings and not the powder convection properties. All the required adjustments are handled automatically by the program once you specify a DED simulation using the AMTYPE command.
At any point prior to solution, specify a DED simulation with a Commands object in both the transient thermal and static structural analyses:
Click the Transient Thermal object and select Commands
from the context menu. Or, right-click
and select Insert > Commands. In the Commands window that is displayed, copy and paste, or type, the
following:AMTYPE,DED
Click the Static Structural object and select Commands
from the context menu. Or, right-click
and select Insert > Commands. In the Commands window that is displayed, copy and paste, or type, the
following:AMTYPE,DED
All other procedures for a DED simulation are the same as in an LPBF simulation.