Ansys Learning Forum Forums Installation and Licensing Ansys Products APDL script written by the DED simulation in Workbench Mechanical Reply To: APDL script written by the DED simulation in Workbench Mechanical

John Doyle
Ansys Employee

Sorry for the confusion.  My answer would apply to LPBF.  DED is more involved.  It typically requires G-Code to define the element "clusters" to be strategically activated (i.e. EALIVE) to simulated the laying down of material.  From  (Chapter 2: Implementation of DED in Mechanical (ansys.com)

Simulation of the Direct Energy Deposition (DED) manufacturing process requires that the analysis follows the print process itself: weld track-by-weld track solidification of the part. Since the thermal (temperatures) and structural (distortion and stress) physics are largely uncoupled (that is, a weak coupling), we can simulate the thermal phenomena first and use those temperature results in a following structural simulation.  From the DED docs...

In a DED process simulation, the model evolves over time, that is, elements are added. We actually mesh the entire part first with Cartesian or Tetrahedron elements and then use the standard element birth and death technique to activate element clusters to simulate the build progressing, where a cluster is defined as a portion of the weld track. Additionally, the relevant boundary conditions also evolve such as thermal convection surfaces. The build step is complete when all the element clusters have been activated (made "alive").

The analysis times and time stepping are also driven by the process parameters and are not known a priori. These details are all handled internally during the solution.

Even though a DED process and a PBF process are similar in some ways, the DED process needs to have a much more detailed level of simulation. A layer-wise simulation is not accurate enough since the velocity of energy deposition is higher in a DED process and so simulation along the weld track over time is required. As the PBF process simulation uses abstractions like super layers (lumping multiple layers for simulation) and layer-by-layer addition (instantaneous element activation for an entire layer), the DED process simulation uses the real welding seams and an abstraction known as element clustering. Clustering is used to split weld lines into smaller pieces of mesh, called clusters, that are exposed to one temperature in a time step. Thus, each cluster is a portion of a weld track that is instantaneously activated using the element birth and death technique. Element clusters are deposited following the deformed shape beneath them rather than in the original undeformed location. You control the size of the cluster with a Cluster Volume option. The solve time and solution fidelity are directly related to cluster volume. The building order of the part can be defined by either applying the G-Code machine file or by using a manual approach of carefully-defined named selections.