From the notes I have, you should use the appropriate icon. On my screen, it is the icon beside the two cubes (white and blue) THe icon looks like un dark grey square with a red line across it. Any way, you can right click on the icon and select "combined simple and detailed element display".
My notes says: Display 1D elements with their associated cross section. The section must have been defined in Hypermesh previous to visualization.
That is all I know. I never tried it actually. If it is anything like Patran, yes, you must use the beam library otherwise, the software only knows the area and the moment of inertias and therefore approximate by a rectangular cross-section.
