Activating the command: Mesh Mesh
3D Mesh Settings
Options
Model button
When the Options button is pressed on the Model Mesh Settings screen and the Model icon is selected, a dialog appears showing the General tab. The Model icon is present regardless of which radio button is selected in the Mesh type section of the Model Mesh Settings dialog.
Which options appear on the Model General tab depend on whether the option Mesh
Mesh
Use VCAD is activated or not. Each control described below will be identified as working with the VCAD mesher, with the legacy mesher, or both.
Automatically refine surface mesh: (Available only when using the legacy mesh engine.) If this check box on the General tab is activated when the model is meshed, a surface mesh will be created on the model. After the surface mesh is created, refinement points will be added depending on the geometry. The model will be meshed again with the refinement points active. If the Solid radio button is selected in the Mesh type section of the Model Mesh Settings screen, a solid mesh will then be generated.
Use automatic geometry-based mesh size function: (Available only when using the VCAD mesh engine.) This one control governs multiple aspects of the surface mesh that normally would require you to set up multiple inputs. In general, it automatically refines the mesh in the areas of curves surfaces. The particular effects are summarized in the following table.
Activated |
Not Activated |
When the mesh size is set based on Percent of automatic (i.e., using the slider), a different mesh size is used for each part. The mesh size is based on the size of the individual part, the number of curves, bounding box dimensions of the part, average length of curves, and so on. |
The mesh size is the same in each part, and is based on the size of the entire model. |
Curved surfaces are meshed more finely depending on the curvature of the surface. A limit is used on the deviation between the planar element and the curved surface, and so on. |
Curved surfaces are meshed based on the user-entered mesh size and refinements. |
The mesh size is anisotropic on curved surfaces, meaning that the ratio of the element's length divided by the element's width is not forced to be near 1. For example, take a mesh size of 1-inch. The mesh in a fillet of 0.5-inch radius and 20-inches long may have elements roughly 0.25-inch by 1-inch. |
The mesh size is isotropic. The element's length divided by the width is near 1. |
The refinement settings on the Options tab of the Model Mesh Settings |
The refinement settings on are available to change. |
In general, the default mesh size is larger. |
In general, the default mesh size is smaller. |
Perform solid meshing at time of analysis: (Available when using either mesh engine.) If this check box is activated and the Solid radio button is selected in the Mesh type section of the Model Mesh Settings screen, the model will not be solid meshed until the analysis is performed. This is convenient for large models that may take a significant amount of time for a solid mesh to be generated. With this option, this time will be combined with the analysis time instead of in a separate operation. If this check box is not activated, a model will be solid meshed immediately after the surface mesh is created.
Number of threads/cores for solid meshing: Sets the number of threads/cores on your machine that you want to use when meshing your solid model. The default value is All.
Multi-cores are used when verifying the surface mesh and for solid meshing, while other mesh operations use a single core. Each part is meshed by one core, not split among multiple cores.
Use virtual imprinting: (Available only when using the VCAD mesh engine.) When activated, the faces of different CAD parts will be split in memory where they intersect each other, without creating additional surface numbers (that is, a virtual imprinting of one surface on another). The virtual model is used as the basis of surface mesh generation. Since the matching virtual surfaces are meshed only once, this will result in a better quality mesh. When unchecked, mesh matching is accomplished by meshing both surfaces of the parts and adjusting the mesh on one part to conform to the mesh on the other part. See Figure 1.
Tolerance: The tolerance for virtual imprinting is specified separately from the mesh matching tolerance. The tolerance field directly beneath the Use virtual imprinting checkbox is used to specify the maximum distance between surfaces and adjacent features, within which distance an intersection will be created. Increase the tolerance if valid intersections are being missed. Decrease the tolerance if unwanted intersections are being created between objects that are close but do not actually meet.
(a) Example solid model consisting of an assembly of multiple parts.
(b) Use virtual imprinting not activated. Virtual surfaces are not created at the arrows.
(c) Use virtual imprinting activated. The surface of the pole is split where the gussets make contact (arrowed), making a new surface in the virtual copy of the model. (New surfaces are not created in the actual model.) |
Figure 1: Use virtual imprinting in a Solid Model |
Perform imprinting within parts: This option will create virtual intersections where different surfaces within a single part meet each other. The action is similar to that of imprinting between parts. This feature is useful for CAD surface models used as a basis of plate/shell FEA models. Such models frequently use single parts comprised of several different surfaces each but without feature lines present along surfaces where an intersection with an adjacent surface occurs.
(a) Example plate model consisting of one part.
(b) Perform imprinting within parts not activated. The virtual feature line is not created at the arrows. The mesh of the gusset may not match the mesh of the pole.
(c) Perform imprinting within parts activated. The surface of the pole is split where the gussets make contact (arrowed), making a new feature line in the virtual copy of the model. The meshes will match. (New feature lines are not created in the actual model.) |
Figure 2: Use virtual imprinting in a Plate/Shell Model |
CAD models are not perfect. Even if the parts are drawn in perfect contact, the internal representation of the surfaces may result in the matching surfaces that are not coincident. In other situations, parts are drawn in their as machined or stress-free condition even though the assembled parts may cause the dimensions to change. For example, the parts in a press-fit assembly are drawn with an interference. Mesh matching tolerances are used to compensate for such discrepancies. Any two nodes that are within the mesh matching tolerance will be snapped together.
On-surface tolerance based on: (Available when using either mesh engine.)
Tolerance value: The value in this field will determine how far the surface mesh process searches for node on coincident surfaces to match the meshes. The meaning of this value --- whether it is a dimension with units of length or a multiplier --- will depend on the option selected in the On-surface tolerance based on drop-down box.
Do not match the mesh of contact pairs when applicable: (Available only when using the VCAD mesh engine.) This option is used to not force the mesh to match or align on two touching surfaces. Since the mesh will not match, the parts will not be connected together. (Note that the mesh may still be the same size and therefore matched if the surface areas are identical.) This option is used only in these situations:
In other analysis types, setting the contact type to Free will accomplish the same goal since the parts will be able to separate.