Converting Mesh Data with Sharp Transitions

The following example demonstrates how you can convert mesh data which includes sharp transitions between faces into an accurate CAD representation of the body.

For bodies which contain sharp transitions between faces, it is recommended you separate the surface into separate patches and then remesh the geometry using the Surface Remesher in Simcenter STAR-CCM+ before importing the mesh data into 3D-CAD.
If you do not remesh and attempt to convert mesh data that does not contain separate patches, the resulting body can include uncontrolled fillets at the interface between connecting faces, to resolve any sharp angles. If you use the Remesh option, without splitting the surface into separate patches, the resulting mesh is squashed as shown below. This occurs because the algorithm has smoothed and blended the two adjacent faces:

To overcome this, you can create part curves on the mesh part and separate the adjacent faces into separate patches. Typically, you perform the following procedure for any .stl file, as this format does not support part curves. Adding the part curves without separating the patches is not sufficient.

  1. Import the surface mesh.


Create part curves on the geometry and split the surfaces:
  1. Right-click the Parts > [Mesh Part] > Curves and select Compute Part Curves.
  2. In the Mark Part Curve Options dialog, define the Part Curve Options, click Apply then Close.


    For more information, see Computing Part Curves.
  3. Right-click [Mesh Part] > Surfaces > Surface and select Split by Part Curves....
  4. In the Split Part Surfaces by Part Curves dialog, define the required Part Surfaces and Part Curves and click OK.


Remesh the mesh part:
  1. Create a new automated mesh operation.
  2. In the Create Automated Mesh Operation dialog, select the following properties:
    Property Value
    Parts [Mesh Part]
    Surface Meshers Surface Remesher
  3. Define the required Default Controls and execute the operation.
  4. Export the new surface mesh as an .inp file.
  5. In the Save dialog, set the Description to the latest description available for the model.
    If you have remeshed the model this can be Automated Mesh.Remesh or Latest Surface. IF you have not remeshed the model the correct description is Root. This ensures you do not export the original mesh.


  6. Create a new 3D-CAD model.
  7. Import the remeshed part into 3D-CAD.


  8. Multi-select the required Body Groups and select Mesh to CAD.
  9. In the Mesh to CAD dialog, select the appropriate setting, ensuring Remesh is deactivated, and click OK.
    The mesh part is converted to a solid CAD body taking into account the part curves which you have created. This produces a CAD part which accurately accounts for the sharp interfaces present between the geometric faces. For this case, the default Complexity of 4 is used. For most cases, the default Complexity value is a good starting point. If the model has a lot of detail, increase the complexity value.

  10. To create a solid body, sew the converted part surfaces
    When you sew the part surfaces together, set the appropriate tolerance to make sure the Sew Sheet Bodies executes correctly. See Sewing Sheet Bodies Together. In some cases, you may need to improve the quality of the sew operation by using the Optimize Edges tool. For more information, see Optimizing Edges