ELASTIC GENERAL INSTABILITY OF RING-STIFFENED CYLINDERS WITH INTERMEDIATE HEAVY FRAMES UNDER EXTERNAL HYDROSTATIC PRESSURE

A machined ring-stiffened cylinder was subjected to hydrostatic pressure to investigate the effect of various sizes of central heavy frames on its elastic overall-buckling strength. The cylinder was tested initially with a large central frame, which was systematically reduced by machining after each successive nondestructive test until it was the size of a typical frame. The tests demonstrated that a heavy frame can be an effective substitute for an internal bulkhead in increasing the general-instability strength of a cylindrical pressure hull. A short empirical solution based on the Levy ring formula has been developed which yields results in close agreement with the experimental findings.