General equations for the stress analysis of rings
This is a 1936 NASA technical report on stress analysis of rings, issued by the NASA Technical Reports Server for engineers and structural analysts. Its two figures are line diagrams of a circular ring cut by diagonal lines, with forces W applied at the cut points, labelled with angles beta, radius r, and x-x and y-y reference axes. A designer could take from them a clean schematic style: a plain circle with radiating force lines, dimension labels, and axis markers suitable for technical diagrams.
