FEM Netzbereich

From FreeCAD Documentation
This page is a translated version of the page FEM MeshRegion and the translation is 58% complete.

FEM Netzbereich

Menüeintrag
Netz → FEM mesh refinement
Arbeitsbereich
FEM
Standardtastenkürzel
Keiner
Eingeführt in Version
-
Siehe auch
FEM Anleitung

Beschreibung

Enables the user to set a localized set of meshing parameters by selecting a set of elements (vertex, edge, face) and applying the parameters to it. It is especially useful for refining meshes in areas of interest or areas where the solver will generate a stronger gradient of a variable. For example, it can be used to refine the mesh around stress-risers (sharp edges, holes, notches, ...) in mechanical analysis, or at areas of contraction in a fluid flow.

Refining the mesh has the advantage of enabling accurate simulation where needed, while allowing coarser mesh in the wider domain, thus drastically optimizing the computation time while maintaining meaningful solutions output.

Anwendung

  1. To enable the function a FEM mesh from shape by Gmsh must be first provided. Select the Mesh object in the Model Tree and either press the FEM mesh refinement button or use the Mesh → FEM mesh refinement menu option.
  2. Press the Add button and select one or more of either faces, edges or vertices in the 3D view to apply the mesh refinement to. The selected items will appear in the list of geometrical objects. The selection mode can be also set to Solid.
  3. Enter the maximum element size for the region.
  4. Click the OK button.
  5. Close the task.
    Result: You now should see a new FEMMeshRegion object under the FEMMeshGMSH object (see example #3 below) in your active analysis container.
  6. Double-click on the FEMMeshGMSH parent object in your Model Tree and press Apply to force a mesh recalculation.
  7. Close the task.

Nachdem das Netz generiert wurde, kann der Eigenschafteneditor verwendet werden, um seine Eigenschaften anzupassen. Nach Änderung einer Eigenschaft, muss der Aufgabenbereich FEM-Netz durch Gmsh erneut geöffnet und die Schaltfläche Anwenden gedrückt werden (der Aufgabenbereich kann geöffnet bleiben, solange weitere Eigenschaften geändert werden).

Es können so viele unterschiedliche Netzbereiche wie nötig erstellt werden.

Visual examples

Beispiel 1: Das grobe Start-NetzGmshAusForm


Example 2: After applying a Mesh refinement using two FEM Mesh Region objects, the large hole is refined to a maximum element size of 3 mm, the smaller hole is refined to 1 mm

Beispiel 3: Ein einfaches Beispiel des entstehenden Modellbaums

Hinweise

The order in which the regions are shown in Tree view can change the mesh result. See this forum thread.

Related

  • "Mesh Regions for a Better Analysis" - Video Tutorial by Joko Engineering (link)