How to Locate a Center Point

When setting up a model for FEA, you may want to perform an operation on the center point of a hole or cylinder (such as adding a mesh refinement point, defining a local cylindrical coordinate system or specifying the element normal point for plate, shell, membrane or composite elements), but often need to determine the coordinates.

You can perform the following technique to locate a center point:

1. Add a line across the diameter of the hole or cylinder - In the FEA Editor environment, use the "Geometry:Add Lines..." command sequence to create a line by clicking on the endpoints as shown in Figure 1. (See How to Add Line Elements.)

Figure 1: In the FEA Editor environment, add a line across the diameter.

2. Divide the line into two lines - Select the line and then use the "Geometry:Divide Lines..." command sequence. The "Divide Lines" dialog will appear. Specify the "Number of Lines" as 2 and click "OK".

Figure 2: Divide the line into two lines.

3. Select the center vertex and inquire on it - After selecting the center vertex, right click anywhere in the working area to access a pop-up menu of options. Choose "Inquire" to obtain the coordinates as shown in Figure 3.

Figure 3: Inquire on the center vertex to find the coordinates.

Note the coordinates and then the lines can be deleted. The coordinates can be used to:

• Define a mesh refinement point in the CAD Solid Model environment (see How to Enhance a Surface Mesh by Using Refinement Points);
• Specify the origin for a local cylindrical coordinate system in the FEA Editor or Superview IV Results environments (see How to Display Results in a Local Coordinate System); or
• Define the element normal on the "Element Definition" screen for plate, shell, membrane or composite elements (see Figure 4). A uniform pressure load can then be applied to the elements, which is directed away from the element normal point.

Figure 4: On the "Orientation" tab of the "Element Definition" screen for plate, shell, membrane or composite elements, the coordinates of the center vertex can be entered to specify the element normal point.

You might find other applications for the demonstrated technique of locating a center point.

For more information about locating a center point, see the ALGOR User's Guide.