General Mechanical

General Mechanical

Additive manufacturing process (DED) simulation help

    • Gmadd
      Subscriber

      Hello,

      for a course project, I'm trying to simulate a direct energy depostition (DED) additive manufacturing process with Ansys 2019 R3 Student.

      As of now, I'm using a Transient Thermal with module an APDL script that generates a moving heat source along a path, a modified version of this Moving Heat Source ACT, paired with a Static Structural.

    • John Doyle
      Ansys Employee
      This is not what we do in Workbench Additive. It is not practical. The goal of AM Process Simulation in ANSYS Workbench is to predict the macro-level distortions and stresses in parts to prevent build failures and provide trend data for improving designs for additive manufacturing including part orientation and support placement and sizing. The simulation done by WB-Mechanical is not meant to provide detailed thermal or structural results needed for prediction of micro-level process phenomena (that is, microstructure). nSimulating the entire build process for a real part following the beam scan pattern would take enormous compute time making it impractical. nSuper layers: Actual metal powder deposit layers are aggregated into finite element ?super layers? for simulation purposes. Since the temperature histories of each adjacent layer is similar, this lumping approach is appropriate. Note: The real machine build time is approximately the transient thermal build step simulation time multiplied by R^(1/3), where R is the number of deposit layers in one element super layer.nLayer-by-layer addition: Material is added and heated all at once for each element layer. For current generation machines and their scan patterns, this is a reasonable assumption. The in-plane thermal effects do not contribute to the distortion as much as the build direction thermal effects. This means we do not use scan pattern information as input.nApplied temperature: Rather than applying heat flux, the entire layer is initially set to the melt temperature. The assumption is that the process parameters for the build have been set appropriately so that (1) the developed temperature is always at or above melt (no lack of fusion) and (2) the developed temperature does not greatly exceed melt.n
    • Gmadd
      Subscriber
      I see, I have a lot to learn.nSince my initial approach is toward smaller parts (20x1mm thin walls, 10 layers tall), I thought the scan pattern simulation would have been necessary.nThe only issue I have is with the temperature: my main goal is to predict distortions in the substrate; wouldn't ignoring its melting (and the re-melting of the successive layers) affect the result too heavily?.Thank you again for your insight.n
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