Constraining Geometries

You can create topological specifications before generating a surface rules mesh.

The Constrain section in the action bar provides tools to add or remove constraints on geometry (edges, vertices, holes...) and to create topology specifications that you can edit at any time. These specifications are stored in the tree under a Topology Specifications set that belongs to the current mesh. These tools are also available from the context toolbar.

For a video example of constraining geometry to edges, see Constrain a Mesh to Edges.

Before you begin: Open the Surface Mesher.
See Also
Creating and Editing Surface Meshes
About Mesh Context Toolbars
  1. Open the Constrain section of the action bar.
  2. To constrain edges, click Constrained Edge .

    Note: Your support selection for constrained edges can include composite grid selections created in the Composites Design app. Using the composite grid as the support enforces a mesh that matches the design of the composite.

  3. To remove constraints on edges, click Unconstrained Edge .
  4. To constrain vertices, click Constrained Vertex .
  5. To remove constraints on vertices, click Unconstrained Vertex .
  6. To constrain holes, click Constrained Hole .
  7. To remove constraints on holes, click Unconstrained Hole .
  8. To project external curves and use the result of this projection to constrain the topology of the mesh:
    1. Click Project Curves .
      The Project Curves dialog box appears.
    2. Select the curves you want to constrain.
    3. In the Tolerance box, enter a maximum distance to project external curves.

      If the distance between an external curve and the mesh is greater than the tolerance value, the curve is not projected.

    4. Click OK.
    A Topology Specifications set containing an Imposed Curves local specification appears in the tree.
  9. To project external curves and use the result of this projection to create compatible meshes around a seam weld:
    1. Click Project Weld Curve .
      The Project Weld Curve dialog box appears.
    2. Select the curves you want to constrain.
    3. In the Tolerance box, enter a maximum distance to project external curves.

      If the distance between an external curve and the mesh is greater than the tolerance value, the curve is not projected.

    4. Specify the Number of layers, and enter the desired height for each layer.

      Multiple layers are supported for welding of separate features and for Self welding of a single feature. However, the mesh for Self welding is optimized only for a single layer.

    5. From the Defined by options, specify whether the mesh edges are to be distributed along the projected curve based on the global Mesh Size (default), Number of Edges, or Local Size.
    6. Select Self welding to allow welding of one geometric feature to itself.

      Self-welding supports connecting seams of sheet metal designs where the folded part needs to be welded to itself.

    7. Click OK.

    Weld curve projection might take precedence over other constraints to ensure a good mesh at the weld, which is often a critical design area.

    A Topology Specifications set containing an Imposed Weld Curve local specification appears in the tree.
  10. To project external points and use the result of this projection to constrain the topology of the mesh:
    1. Click Imposed Points .
      The Imposed Points dialog box appears.
    2. Select the points you want to constrain.
    3. In the Tolerance box, enter a maximum distance to project external points.

      If the distance between an external point and the mesh is greater than the tolerance value, the point is not projected.

    4. Click OK.
    A Topology Specifications set containing an Imposed Points local specification appears in the tree.
  11. To create a virtual topology that you can select as a support for mesh specifications:
    1. Click Group Geometries .
      The Grouping dialog box appears.
    2. Select the supports you want to group.

      You can select only 1D or 2D geometries, and the selection must be homogeneous (you cannot select both 1D and 2D geometries).

    3. Click OK to create the grouping specification.

    Important: You cannot select grouping specifications as a support for other topology specifications. You can select grouping specifications as a support for mesh specifications (for example, an edge distribution). However, the mesh specification might not be applied if the specified group is split by another topology specification such as an imposed curve.

  12. To cut an edge, click Cut Edge and select cut point along the desired edge.

    The edge is cut, creating a new vertex at the selected point.

  13. To divide a domain, such as a face, into two separate regions, click Split Domain and select two supports to define the split.

    After selecting the first support, a dashed line indicates where the split will be created based on the current cursor position. You can select either existing vertices or edges (the point selected along the edge is used, if appropriate).

    If you select Orthogonal Split Domain , an orthogonal projection is used.

    The domain is split along a new edge defined by your choices.
  14. To merge two topological edges, click Merge Edges and select the edges to merge.

    Reducing the number of edges in an area helps simplify the mesh by removing unnecessary constraints. The selected edges must join the same vertices.

    Tip: You can use Collapse Edge to make nearby edges end on the same vertex.

  15. To reduce a short edge into a single vertex, click Collapse Edge and select the edge.