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FEM MeshNetgenFromShape/zh-cn

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FEM MeshNetgenFromShape

Menu location
Mesh → Mesh From Shape by Netgen
Workbenches
FEM
Default shortcut
None
Introduced in version
-
See also
FEM tutorial

Solvers
All

描述

For a finite element analysis, the geometry needs to be discretized into a FEM Mesh. This command uses Netgen (which needs to be installed on the system) to generate the mesh. Netgen meshes are not supported by Elmer.

Depending on your operating system and installation package, Netgen might be bundled with FreeCAD or not. For further information see FEM Install.

introduced in 1.0: The refactored Netgen mesher is available. It can be activated in the preferences and is installed via Python bindings as explained on the aforementioned FEM Install page.

用法

  1. Select the shape you want to analyze. For a volume, this needs to be solid or compsolid. A compsolid is necessary if your part is made from multiple materials (a compsolid can be created with the Part BooleanFragments command).
  2. There are several ways to invoke the command:
  3. Optionally, set the max/min element size (the default setting usually creates meshes that are too coarse) and element order (using the Second Order checkbox).
  4. Optionally, change the Fineness to one of the predefined choices or choose UserDefined and manually edit the parameters.
  5. Click the Apply button to generate the mesh. introduced in 1.0: Optionally, use the Cancel button to abort meshing if using the new Netgen implementation.
  6. Click the OK button to generate the mesh and close the dialogue. You can also click the Cancel button to cancel the changes or creation of the mesh object.

Properties - Legacy Netgen

  • 数据Max. Size: Maximum size of the element in mm.
  • 数据Min. Size: introduced in 1.0: Minimum size of the element in mm.
  • 数据Second order: Second order elements contain more nodes per element. Usually, it is enough to use rougher mesh to obtain same solution precision as with the first order elements,
    • true (default); second order elements,
    • false; first order elements.
  • 数据Fineness: Offers predefined levels of mesh density.
  • 数据Growth Rate: Defines how much adjacent elements can differ in size.
  • 数据Nb. Segs per Edge: Defines the minimum number of mesh segments per edge.
  • 数据Nb. Segs per Radius: Defines the minimum number of mesh segments per radius.
  • 数据Optimize:
    • true (default): applies optimization algorithm to improve mesh quality
    • false

Properties - Refactored Netgen

  • 数据Bad Element Limit: Limit for max element angle (150-180).
  • 数据Base Element Np: If non-zero, baseelement must have BaseElementlNp points.
  • 数据Block Fill: If enabled, block filling is performed.
  • 数据Check Chart Boundary: If enabled, chart boundary is checked.
  • 数据Check Impossible
  • 数据Check Overlap: If enabled, overlapping surfaces are checked.
  • 数据Check Overlapping Boundary: If enabled, overlapping surface mesh is checked before volume meshing.
  • 数据Close Edge Factor: Factor to restrict meshing based on close edges.
  • 数据Curvature Safety: Safety factor for curvatures (elements per radius).
  • 数据Delaunay: If enabled, Delaunay algorithm is used for 3D meshing.
  • 数据Delaunay2d: If enabled, Delaunay algorithm is used for 2D meshing.
  • 数据Element Order: High order element curvature.
  • 数据Element Size Weight: Weight of element size with respect to element shape.
  • 数据End Step: Last step:
    • AnalyzeGeometry
    • MeshEdges
    • MeshSurface
    • OptimizeSurface
    • MeshVolume
    • OptimizeVolume
  • 数据Fill Distance: Block filling up to distance.
  • 数据Fineness: Offers predefined levels of mesh density:
    • VeryCoarse
    • Coarse
    • Moderate
    • Fine
    • VeryFine
    • UserDefined
  • 数据Give Up Tolerance: Give up quality class for 3D meshing.
  • 数据Give Up Tolerance2d: Give up quality class for 2D meshing.
  • 数据Give Up Tolerance Open Quads: Give up quality class for closing open quads, greater than 100 for free pyramids.
  • 数据Glue: introduced in 1.1: Glue shapes to get a conformal mesh.
  • 数据Growth Rate: Grading for local h.
  • 数据Heal Shape: If enabled, shape is healed before meshing.
  • 数据Invert Tets
  • 数据Invert Trigs
  • 数据Local H: If enabled, uses local h.
  • 数据Max Outer Steps: Maximum outer steps.
  • 数据Max Size: Maximum size of the element in mm.
  • 数据Min Size: Minimum size of the element in mm.
  • 数据Only3d Domain Nr
  • 数据Optimization Error Power: Power of error to approximate max error optimization.
  • 数据Optimization Steps2d: Number of 2D optimization steps.
  • 数据Optimization Steps3d: Number of 3D optimization steps.
  • 数据Optimize2d: 2D optimization strategy.
  • 数据Optimize3d: 3D optimization strategy.
  • 数据Parallel Meshing: If enabled, uses parallel meshing.
  • 数据Quad Dominated: If enabled, uses quad dominated surface meshing.
  • 数据Relinner Safety: Radius of active environment (times h).
  • 数据Safety: Radius of local environment (times h).
  • 数据Second Order: If enabled, uses second order element meshing.
  • 数据Second Order Linear: If enabled, second order nodes are created by linear interpolation.
  • 数据Segments Per Edge: Minimum number of segments per edge.
  • 数据Sloppy: Quality tolerances are handled less careful.
  • 数据Star Shape Class: Class starting star-shape filling.
  • 数据Start In Surface: If enabled, starts surface meshing from everywhere in surface.
  • 数据Start Step: First step:
    • AnalyzeGeometry
    • MeshEdges
    • MeshSurface
    • OptimizeSurface
    • MeshVolume
    • OptimizeVolume
  • 数据Try Hexes: If enabled, tries hexahedral elements.
  • 数据Use Local H: If enabled, uses local H.
  • 数据ZRefine: introduced in 1.1: Z-refinement for extruded shapes, can create extruded hex meshes when combined with the Quad Dominated property. Will work only for first-order meshes (unless the generated elements are all hexahedrons):
    • No - Z-refinement is disabled
    • Regular - all elements have the same height
    • Custom - the height of each element must be specified
  • 数据ZRefine Direction: introduced in 1.1: Z-refinement direction (change if the shape is extruded in a direction other than the Z-axis).
  • 数据ZRefine Size: introduced in 1.1: Z-refinement size (element height) given as a fraction of the shape size (total height). For a regular partition, only one value is needed.