General

General

Additive Print: What is the logic behind the thermal strains calculated in Workbench Additive vs Additive Print?

    • FAQFAQ
      Participant

      In Workbench Additive, there is no heat flux or heat source input. We essentially just say that the thermal stress starts building when the material begins to solidify. So we set the temperature of the layer to melting temp. A parallel would be in Mechanical rather than apply a force to a face, you specify a displacement that you know will happen we are essentially setting the DOF to a known value rather than solving for it. The only variable we use here is to modify the time between layers by (element size/layer thickness)^(2/3) to make sure we get more consistent temperatures across different element sizes. In additive print, the only place where heat flux would be used would be in the thermal strain simulation during the thermal solve process. In that case, we actually trace the path of the laser so there is no averaging being done at all. First, we solve just for the temperature history of the whole build independent from displacement or stress that’s where the heat flux equations would be involved in the thermal solver. Then once we have the temperature history of every element in the model a static structural analysis is performed using an assumed strain model but we also calculate a ratio of the strain in all three directions (parallel to the laser, perpendicular to the laser, in the depth of the part) based on the scan pattern as well along with the temperature history of that particular element in the stress calculation.