Product: Abaqus/CAE
Benefits: Tetrahedral meshing algorithms have been improved to provide more accurate meshing for spline faces and virtual combined faces. Boundary meshing has also been improved, and Abaqus now uses quadratic tetrahedral elements by default instead of linear elements in some cases. Transitions from small to large mesh elements are more gradual than in past releases, the meshing of narrow regions has been improved, and you now have more control over the size of interior elements.
Description: The triangular surface meshing process has been improved to minimize gaps between the boundary nodes and the geometry prior to generating the tetrahedral mesh. The former process sometimes resulted in a bumpy mesh for certain curved surfaces if quadratic elements were used, as shown on the left in Figure 12–1. The image on the right shows the quadratic mesh with the new enhancements.
In addition, if you choose tetrahedral meshing instead of hexahedral, hex-dominated, or wedge meshing to mesh a three-dimensional region, Abaqus now uses quadratic-order tetrahedral elements as the default instead of linear tetrahedral elements. However, Abaqus may still use linear tetrahedral elements if nondefault element types were selected before you chose to use tetrahedral meshing.The boundary meshing process has been improved to prevent poor boundary elements from causing the tetrahedral mesh to fail. Figure 12–2 shows a tetrahedral mesh generated in Abaqus 6.10 with an element error highlighted and the same mesh generated in the current release containing no errors.
Several enhancements were made to reduce the occurrence of flat triangular elements in the boundary meshes. These changes include local mesh refinement and shape optimization. Figure 12–3 shows a triangular mesh for a thin circular section with coarse seeding. The image on the left was generated in Abaqus 6.10, and the image on the right shows the same model meshed with the current release.
Finally, an improved user interface for interior element growth provides you with greater control over element growth within a tetrahedral mesh. Where previously you could choose either moderate or maximum growth, you can now either enter a numerical growth rate or use a slider control to choose a growth rate. Either option allows you to select values between 1.0 (minimal growth) and 2.0 (fast growth). Table 12–1 shows the relationship between the Abaqus 6.11 interior element growth controls and those available in previous Abaqus releases. If you open a model from a previous release, Abaqus/CAE automatically converts the interior element growth values to their numerical equivalents.
Table 12–1 Interior element growth for tetrahedral meshes.
| Abaqus 6.10-EF or earlier releases | Equivalent Abaqus 6.11 growth rate |
|---|---|
| Increase size not selected. | 1.05 (default) |
| Moderate growth | 1.2 |
| Maximum growth | 2.0 |
Note: The enhancements to tetrahedral meshing may result in significant changes to an existing mesh when you upgrade models to the current release and remesh them.
