Experiments on the buckling under internal pressure of thin torispherical ends of cylindrical pressure vessels

Abstract

Ten cylindrical pressure vessels with torispherical ends, all of the same constant nominal thickness, were tested under internal pressure to observe the buckling behaviour of the toroidal knuckle. All specimens were of constant internal cylinder diameter to thickness ratio of 531·5. The sphere radius was equal to the cylinder diameter and only the torus radius was varied. Buckling was detected by rotating probes at the sphere/torus junction and at the mid-point of the torus. The buckling pressure increased with increasing torus radius and the two specimens with the largest torus radii did not buckle. For all specimens, the change of meridional shape with increase in pressure was measured. For one specimen, strain gauges were used to study the variation of circumferential strain on the inside and outside surface at the sphere/torus junction due to variation in thickness round the circumference. A simple theoretical expression for the buckling pressure, similar to the Rankine formula for a strut, is suggested. © 1978.