About Direct Energy Deposition

To simulate direct energy deposition additive manufacturing, you must understand the features and data required to run this process.

Direct energy deposition simulation processes encompass two types of additive manufacturing: fused deposition modeling (FDM) and laser direct energy deposition (LDED).

This page discusses:

See Also
Defining Direct Energy Deposition

Event Series Data

You can obtain event series data from existing app data or specify the data for the simulation.

If the simulation is based on the Material Deposition Fabrication app, the Material Deposition Fabrication app provides the toolpath event series. The provided toolpath contains columns for the laser power, bead height, bead width, and tool orientation. You can override the toolpath with an external document if required.

For user-provided event series data, you can determine whether the bead height, bead width, or tool orientation vary. If any of these parameters vary, the event series document you provide must have entries for them. You must enter the value of any fixed parameters directly into the user interface. All event series must have a power column.

Element Activation

You can specify the fraction of material that activates the elements and whether the elements are partially or fully activated when enough material is added. You can control whether the elements remain in their initial positions when they are activated or whether they follow the position of previously activated elements.

You can change the time increment over which thermal strains are ramped up when elements are activated. Applying the strains gradually can aid in solution convergence, especially when there is plasticity. The default constant is two times the initial time increment in the static step.

You also have a degree of control over the volume fraction calculation that determines when elements are activated. Element subdivision supports an automatic setting (0) and two levels of precision (1 and 2), where 2 is the more accurate setting.

If there is significant model deformation and inactive elements do not follow the deformation, they can distort due to their connection to the motion of the active elements. When the inactive elements are activated, the distortion can cause problems with the simulation. For more information, see About Material Activation.

Heat Source and Absorption

You can decide if a heat source is included in the simulation and how the heat absorption into the model is managed. If you omit the heat source, the initial temperature of the additive material drives the thermal analysis. If you include the heat source, the power of the heat source and its motion drive the thermal analysis.

When you include the heat source, you can access additional controls, such as the heat density model of the laser power. By default, this distribution is concentrated, which means the energy is concentrated on a single point.

You can select a uniform heat distribution to model the energy density as a box. You can specify subdivisions and box lengths to define the region of influence around the laser.

The last heat distribution option is the double ellipsoid Goldak model. The Goldak expression for energy distribution, q , from a laser source is shown in the image below. Q denotes the laser power. The local x-axis indicates the laser motion direction defined by an event series segment.

You can supply entries for subdivisions, a, b, cf, cr, ff, and fr, and a box size factor to define the region of influence around the laser. For more information, see Specifying a Moving Heat Source with a Goldak Distribution.

The absorption value describes the fraction of the heat energy from the heat source that is absorbed by the part. This value is required, and it must be between 0 and 1. By default, the absorption is a single value, but you can also specify a table of temperature-dependent values.

Energy Conservation

On exterior surfaces of the part, a portion of the heat source volume that you define might be outside of the mesh boundary. You can control how the heat energy is dissipated in this situation. You can conserve the total energy (use enhanced conservation) to increase the power inside the mesh boundary to make up for the portion of the heat source that is outside the mesh boundary. If you do not use conservation, only the energy associated with the heat source volume inside of the mesh is applied to the part (some thermal energy is lost).