Hollow Ellipse
The icon for a hollow ellipse beam section type looks like this:
When you select Hollow Ellipse as the beam type on the Beam Section Definition dialog box, you must enter positive values for the following cross-section dimensions:
a—the length of the major (longer) cross section of the outer ellipse
b—the length of the minor (shorter) cross section of the outer ellipse
ai—the length of the major (longer) cross section of the inner ellipse
Select units for length or use the default principal units.
The inside minor axis is calculated by making its ratio to the inside major axis the same as the ratio of the outside minor axis to the outside major axis, as shown in this equation:
Inside Minor = (Outside Minor/Outside Major) Inside Major
If you want to examine the exact effects of shear on a beam, specify positive values for Shear FactorFy and Shear FactorFz. These factors represent the ratio of a beam's effective "shear area" to its true cross-sectional area for shear in the principal Y and Z directions. The default is 0.833333, which is accurate for rectangular cross sections.
The figures below illustrate the stress recovery points for hollow ellipse section types. The figure on the left shows the points in native mode, and the figure on the right shows the points in FEM mode.