There are many situations where you are more concerned with the accuracy in certain areas of a model than others. Therefore, you will want to have a fine mesh in those areas to ensure accurate results. However, if you create the surface mesh of the entire model with a fine mesh size, you may spend unneeded time analyzing the fine mesh in regions where the results are not as important to you.
The solution to this problem is to use refinement points. A refinement point specifies a volume of space in which a finer mesh will be generated. These can be added in the FEA Editor environment using these methods.
Refinement points are used for CAD solid models, surface mesh enhancement, and 2-D mesh generation. Unless indicated otherwise, the following applies to all three types of meshing.
Specifying Specific Regions for Refinement
The easiest way to define a refinement point at a certain location – especially for CAD solid models – is to do the following:
Create a coarse surface mesh on the model.
Using the "Selection: Shape: Point" and "Selection: Select: Vertices" commands, click on a vertex near the center of the area where you want to use a finer mesh.
Right click in the working area and select "Add: Refinement Points..." command.
In the "Effective radius" field, enter the distance, in the units of your model, around that point that you want to be refined. For example, if your model was constructed in inches and you enter a value of 1.0, the mesh in an 1 inch radius sphere centered at the selected vertex will be refined.
If using the "Mesh size" field, enter the desired length, in the units of your model, of the sides of the elements in this region. This size will be applied to all of the elements starting at the selected vertex and radiating outward to the radius specified in the "Effective radius" field. This value must be less than the average mesh size listed below this field. That is, the mesh can only be made smaller, not larger.
If using the "Divide factor" field, enter the desired factor. The mesh inside the effective radius will have a mesh size of (mesh size)/(divide factor). That is, the divide factor is a whole number larger than 1.
Press the "OK" button.
Repeat this process in all of the areas where you want the mesh refined.
Now you can either recreate the mesh or use the "Mesh: Enhance Surface Mesh..." command to enhance the mesh. Both processes will recognize and apply the localized refinement around the refinement points. It is recommended to recreate the surface mesh.
If you want to change the parameters of an existing refinement point, you can select it, right click in the display area, and select the "Modify" command. This will take you back to the screen shown above. (You can also select the "Mesh: Refinement Points: Specify..." command. This will access the screen described below that lists the parameters of all of the existing refinement points. You can change any of these parameters and they will be applied to the mesh when you recreate it.)
When working in a sketch on a drawing plane – usually for a 2-D mesh generation – a refinement point can be added to the sketch by right-clicking at the desired location and choosing "Add: Refinement Points...". The dialog described above will be shown.
If you want to define a refinement point at a known coordinate where a node does not exist, for example in the center of a hole, you can use the "Mesh: Refinement Points: Specify..." command.
Press the "Add" button. You will be able to enter in the X, Y, and Z coordinates for the point on your model that you want to refine around in the respective columns.
In the "Radius" column, enter the distance, in the units of your model, around that point that you want to be refined. For example, if you accept the default coordinates of the origin (0,0,0) in the X, Y and Z coordinate columns, and leave the default value of 1.0, the mesh in a 1 inch radius circle centered at the origin will be refined.
In the "Mode" column, choose either "Size" or "Divide".
If using the "Size" mode, enter the desired length in "Mesh size" column, in the units of your model, of the sides of the elements in this region. This size will be applied to all of the elements starting at the point specified in the X, Y, and Z coordinate columns and radiating outward to the radius specified in the "Radius" column.
If using the "Divide" mode, enter the desired divide factor in the "Divide factor" column.
If you want to refine the mesh in another area, press the "Add" button and repeat the previous three steps.
If you want to delete a previously defined refinement point, highlight the row and press the "Remove" button.
If you want to delete all of the previously defined refinement points, press the "Clear All" button.
Once the refinement points are specified as desired, press the "OK" button.
Now when you perform the mesh generation, the mesh in a spherical area around the refinement points will be the size specified for the refinement point while the rest of the mesh will be the size specified in the appropriate settings dialog.
Using Automatic Refinement
This command is applicable to CAD solid models only.
The "Automatic" command in the "Mesh: Refinement Points" pull-out menu will access the "Automatic Refinement Points" dialog. In this dialog, you can use the slider to specify the level of refinement you want to use. The farther to the right that you move the slider will result in more refinement points. When you press the "Generate" button, the model will be analyzed for short features. Refinement points will automatically be added in these regions.
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