About Meshes

Finite Element Method

The finite element method consists of splitting complex geometries into small, simple pieces—finite elements—whose behavior is known. The process of splitting a complex geometry into finite elements is called meshing. When meshing, some elements are more suited for particular geometries than others. For a video that highlights these differences, see Basics of Element Selection.

Points along the edges and corners of finite elements are called nodes. In a stress simulation the displacements of the nodes are the fundamental variables that the solver calculates. Once the nodal displacements are known, the stresses and strains in each finite element can be determined.

Mesh Geometry

The geometry support is essential to the mesh definition. You can select elements, edges, faces, and polyhedral data as a geometric support for the mesh.

When you create a mesh, you specify a geometric support that is typically created or imported in apps on the 3DEXPERIENCE Platform. You can mesh exact geometries created with geometric operators, or you can mesh polyhedral geometries, described by a set of facets.

Polyhedral Data

Each type of support has its own merit. Meshing polyhedral data has many applications. For example, it is useful for complex simulations of survey data such as solids and surfaces for engineering projects including roads, tunnels, dams, and reservoirs.

Mesh Creation fully supports polyhedral data for beam meshes. However, there are a number of limitations when using polyhedral data for surface and tetrahedron meshes:

Limitations for both surface and tetrahedron meshes:
- Virtual grouping does not take into account face curvature; it only includes face discontinuities (the angle between the faces).
  Note: You can work around this limitation by manually constraining or unconstraining the edges of the virtual topology.
- All topological specifications are supported except for Project Weld Curve parameters.
- All meshing specifications are supported except for Face Capture parameters.
- 2D Holes rules are the only shape rules supported from the group of Feature parameters.
In addition, tetrahedron meshes have the following limitation:
- The Boundary layers specification, Exclude from Global Boundary Layers is not supported.

Mesh Color

Colors are used to indicate the element quality of meshes or to indicate topological constraints.

Element Quality

Green elements indicate that the mesh elements are processed by the solver without any problem (good mesh quality). Yellow elements indicate that the mesh elements are processed by the solver with very few possible problems (poor mesh quality). Red elements indicate that the mesh elements are unlikely to be properly solved (bad mesh quality).

Mesh elements are colored:

Green to indicate that the mesh elements are processed by the solver without any problem (good mesh quality).
Yellow to indicate that the mesh elements are processed by the solver with very few possible problems (poor mesh quality).
Red to indicate that the mesh elements are unlikely to be properly solved (bad mesh quality).

Topologic Constraints

Constraining edges, holes, or vertices ensures that those topologic constraints are respected and maintained during the mesh operation. Otherwise, those geometries are ignored during meshing and might not be present in the final mesh. Color coding helps you to visualize the constrained edges, holes, and vertices.

Edges

An edge is highlighted in:

Yellow if the edge is constrained.
Blue if the edge is not constrained.

Holes

A hole is highlighted in:

Green when the hole perimeter is considered to be a free edge (which is constrained automatically).
Blue if the hole is not constrained.

Vertices

A vertex is highlighted in:

Red if it connects more than two edges. The vertex is constrained automatically, and you cannot remove the constraint.
Yellow if it connects two edges. The vertex is constrained automatically.
Blue (or hidden) if it is not constrained.