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FEA Mesh
Defining the FEA Mesh
The FEA mesh is created by defining key points, connecting them with paths, linking the paths to mesh an area, and finally assigning material properties to each element.
Standard Mesh Creation
The following commands are used to create a mesh:
- Keypoint: Define a keypoint used in defining Paths.
- Keypoints: Add multiple defined keypoints to a Path.
- Origin: Define coordinate system origin for entry of Keypoints using polar coordinates.
- Path ... EndPath: Define a path used in defining Areas.
- Paths: Add multiple defined paths to an Area.
- Area ... EndArea: Define an area for mesh generation.
- Element: Define type of element to use in the mesh.
- FlipTriangles: Select the direction of triangular elements in meshes that use those elements.
- Resequence: To turn on the option to resequence the nodes, which will minimize the bandwidth of the problem and speed the calculations.
Using Images or Shapes to Define the Mesh
An advanced method for creating FEA meshes is to create them using image and shape commands. The procedure for using this method is:
- Create a standard mesh, but for sections of the mesh that will be set from image or shape commands, set the material id in the Area Command to
_NONE_
The material will be determined later by subsequent image and shape commands.
- Once the initial mesh is ready, use one or more interspersed BMPRegion, Region, or Hole commands. These commands will map elements covered by the image or by shapes to the material (or hole) associated with the command.
- When the mesh is done, any elements initialized to
_NONE_
but not assigned to a material by an image or shape command will automatically be removed from the mesh. If these removals cause the mesh to be partitioned into disconnected sections, however, the FEA analysis will fail. A good way to verify connectivity is to attempt to resequence the nodes.
The commands for using images and shapes are:
Within a Region or Hole block, the geometry for the elements or the hole are defined by any number of 2D shape commands.