Volume Properties - PDS - Help

Interactive Section Tables Help

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This option is used to create the engineering properties of three-dimensional volumes.

These engineering properties are calculated about the centroid of the volume. The engineering properties for 3-D volumes are calculated by slicing the element, calculating the properties for each slice and combining the results using numerical integration. The number of slices controls the accuracy of the calculation.

There are two parameters, Density and Number of Slices that directly affect not only the accuracy of the calculation but also the time it takes to calculate the engineering properties. As the number of slices increases, the accuracy and the calculation time increases.

During the creation of arbitrary sections, thinwall sections, and volumes, the user can choose to create a designator. A designator is a symbol (triad) that is associated with the graphics used to create the section. Designators can be labeled with the section name. The properties associated with the designator can be reviewed by simply selecting the designator. When a designator is created, it is placed at the center of the section and indicates the directions of the principle axes of the section.

Before Using This Option

  • Use MicroStation to draw the volume element. You can use solid shapes, surfaces, and truncated cylinders (regular cones and volumes created with the MicroStation Surface Of Revolution command are invalid). For the front and back faces, used only ellipses, line strings, shapes, or complex shapes made up of lines, arcs, and line strings. Each face must have the same number of vertices; however, they can be twisted or skewed with respect to one another.

  • IST assumes that the front and back faces are closed. For example, if a line string is drawn with three sides and an opening, Interactive Section Tables assumes that the forth side has been drawn to close the shape. The shape is invalid if any of the lines cross --- whether they are actual lines or lines that are assumed to be there to close the shapes.

  • You cannot store the shape of the volume in the cell library for later placement. You can only calculate volume engineering properties.

  1. Click Section > Create.

  2. Select the volume properties icon from the Section Type option.

  3. Select Section Name and type in a name for the volume properties to be created. The name can be up to 40 characters long.

  4. Click the Create Volume Designator check box if you want to include this option.

    When a section is associated with an area designator, it is considered to be locked. To unlock the section, you must use the Designator - Disconnect command explained in the Disconnect Section. 

    IST prompts: DB: Select Volume RST: Backup

  5. Click data point to select volume. If the volume was created using the MicroStation Surface Of Projection, you must select the volume that was created rather than the original surface.

    The volume highlights.

    IST prompts: Accept/Reject

  6. Click data point to accept the highlighted volume.

    The system displays Processing Sections and Volume Section Complete.