Thermal-Structural Additive Manufacturing Workflow

Additive Manufacturing Scenario Creation guides you through the workflow for a typical sequential thermal-structural analysis to simulate the distortions that might occur during the 3D printing process.

A thermal-structural analysis generally provides a more accurate simulation than an eigenstrain analysis. However, it also is a bit more complex to set up and often takes longer to run than an eigenstrain analysis.

A typical workflow for a thermal-structural additive manufacturing analysis is outlined below. Each step corresponds to the sections displayed in the Assistant.

Tip: Use the standard area of the action bar to activate the Assistant if it has been closed.
  1. Setup the model.
    • Create or select a finite element model.
    • Assign separate mesh sizes for the build geometry, the build tray, and the supports.
    • Define the shell thickness for the supports.
  2. Create the Meshes.
    • Create meshes for the printed parts, supports, and the build plate.

      The app automatically generates meshes for parts and supports that have associated slicing and scanning information and for the build plate.

    • Select additional meshing algorithms, if required.
  3. Define the Part & Support Properties.
    • Assign section properties to the model.

      The app creates section properties automatically if there is existing slicing data.

    • Connect the different parts together. Create tie connections between the part, supports, and the build tray.
  4. Define Initial Temperatures for both the thermal and structural analysis cases.
    • Define chamber temperature for the thermal analysis case. In the thermal analysis case, the chamber temperature is the initial temperature of the printed part. The temperature of the incoming material is expected to be the same as the chamber temperature. For example, the initial temperature of the powder material as it is being spread by the recoater is the room temperature. The heat source (for example, the laser) is modeled independently as a moving heat flux.
    • (Optional) Define an initial temperature for the build tray.
    • Define initial temperatures for the structural analysis case.

      In the structural analysis case, the initial temperature represents a relaxation temperature (not room temperature) above which thermal straining induces negligible thermal stresses. In the analysis, at material activation, the initial temperature is the temperature from which the initial thermal contraction occurs. This temperature is material-dependent, and it is no higher than the melting temperature of the material.

    • Define a melting temperature for the structural analysis case. In the structural analysis case, the melting temperature is the initial temperature of the printed part. For a part-level simulation, at material activation the initial temperature is the temperature from which the initial thermal contraction occurs. The melting temperature represents a relaxation temperature, above which thermal straining induces negligible thermal stresses. The melting temperature is used as the initial temperature for the material being deposited. For a detailed process-level simulation, set this melting temperature to the chamber temperature.
  5. Define the Moving Heat Source.
    • Apply a moving heat source to simulate the heat addition of an additive manufacturing process.

      The moving heat flux captures the information required for the laser motion over time, either from external sources or from existing slicing data. When used with existing slicing data from the Powder Bed Fabrication app, it also automatically gathers the laser path data and converts it to an event series.

      If the event series originates from the Powder Bed Fabrication app, the z value for the laser path is always half a layer below the z value for the roller.

    • Configure the interface to match custom user subroutine data that aligns with your additive manufacturing process, if required.
  6. Define the Material Deposition.
    • Define how the material is added to the printing process, which controls the activation of the finite elements over time.

      The material input captures the information for material deposition over time, either from external sources or from existing slicing data. When used with existing slicing data from the Powder Bed Fabrication app, it also automatically gathers the roller motion data.

    • Configure the interface to match custom user subroutine data that aligns with your additive manufacturing process, if required.
  7. Define the Cooling to be applied to parts that have existing slicing data.
    • Define the convective and/or radiative cooling of the free surface as it evolves over the course of the print process.
    • Specify either convection or radiation or both.
  8. Define the Prescribed Temperatures.
    • If required, define any temperature boundary conditions for the thermal analysis.
  9. Create Structural Restraints & Loads.
    • Apply restraints to prevent rigid body motion of the part in the structural analysis.

      A clamp restraint is sufficient since there are no in-service loads being applied during the manufacturing simulation.

  10. Simulate.
    • If required, perform checks before solving the simulation.
    • If required, configure the simulation options, including selecting local or remote execution.
    • Start the solve.

      You can check or run just the thermal simulation or both the thermal and structural simulations.

  11. Postprocess the Results.
    • Create plots and visualize results.

      For example, you can create contour plots that display results using a spectrum of colors with corresponding values.

    • If required, create sensors, which can be used in external simulations.

 

See Also
About Additive Manufacturing
Eigenstrain Additive Manufacturing Workflow