Sometimes you may have specific locations on your model which are critical to the accuracy of your results. To help improve the way the results represent the behaviors of these critical locations in simulated operating conditions, you may need to apply specific mesh controls to the model before starting the meshing process.
The methods of mesh conditioning in Creo Elements/Direct Finite Element Analysis are all based on the principle that results are calculated at nodes. Consequently, the more nodes concentrated in critical areas of the model, or the more precisely we can place individual nodes, the greater the degree of accuracy in the results derived from those nodes.
Creo Elements/Direct Finite Element Analysis allows you to condition the mesh generation in three ways:
When preparing a thin-walled part, you may need to specify many constraints to achieve a mesh that Creo Elements/Direct Modeling can solve. Use Auto Create to have Creo Elements/Direct Modeling you create the constraints.
The command will create mesh size constraints for:
• Sharply bent faces (cylinders with a small radius less than two times the mesh size).
• Tightly curved edges (with a local radius less than two times the mesh size).
• Straight edges, if requested.
This command works only for parts with a Creo Elements/Direct Sheet Metal Material attribute attached or an already created shell mesh.
To create mesh conditions automatically,
1. Click Modify and then, in the Mesh group, click the arrow next to Conditions.
2. Click Auto Create. The ShellAutoConstraint dialog box opens, with the current study, if any, automatically available in the Study box. If there is no current study, or if you wish to select a different one, specify the name of the study in the Study box.
3. Select any desired sub-options. The following sub-options are available:
◦ Global ElemSize (Global Element Size) allows you to specify the size of the elements used to create the mesh. Clear the box if you do not wish to specify the size. Creo Elements/Direct Finite Element Analysis calculates an average default element size to use for meshing the part based on the dimensions of the geometry. This value is displayed in the Global ElemSize box. You can accept this value or enter a new element size in the Global ElemSize box.
◦ ElemOrder (Element Order) allows you to select:
▪ Linear: Creates elements with nodes only at the element vertices. Use Linear elements only for a quick first impression of the structural situation. For more accurate results always use quadratic elements.
▪ Quadratic: Increases the number of nodes per element. Additional nodes are at the midpoints of the lines connecting the element vertices. In most cases, a quadratic element order improves the accuracy of the results but requires more processing time by the solver. (This is the default.)
▪ P-Elements: Increases the order of the polynomial that interpolates
◦ ElemShape (Element Shape) allows you to select the shape of the finite elements used to construct the mesh (see the graphics below). The choices are: functions within the element.
▪ Solid:Tetra (default) - Solid tetrahedral elements; that is, a solid mesh consisting of regular bodies having four triangular faces.
▪ Surface:Triad - Triangular surface elements; that is, a surface mesh consisting of triangles. If you're not certain which surface element shape to use, select Surface:Triad.
▪ Surface:Quad - Quadrilateral surface elements; that is, a surface mesh consisting of four-sided elements.
4. Click the CnstrnStr check box if you wish to constrain the straight edges.
to complete the operation.