Elastic buckling of ring-stiffened cone-cylinder intersections under internal pressure

Cone-cylinder intersections are commonly found in pressure vessels and pipi ng. Examples include conical end closures to cylindrical vessels and conica l reducers between cylinders of different radii. In the case of a cone larg e end-to-cylinder intersection under internal pressure, the intersection is subject to a large circumferential compressive force. Both the cone and th e cylinder may be thickened near the intersection to resist this compressio n, but it is often convenient and necessary to augment further the strength of the intersection using an annular plate ring stiffener. Under this larg e circumferential compression, the intersection may fail by elastic bucklin g, plastic buckling or plastic collapse. This paper describes an investigat ion of the elastic buckling strength of ring-stiffened cone-cylinder inters ections. Two buckling modes are identified: a shell mode for thin intersect ions with a shallow cone (a cone with its apex half angle approaching 90 de grees) and/or a relatively stocky ring stiffener, and a ring mode for other cases. An existing elastic buckling approximation for annular plate rings in steel silos is found to be applicable to the intersection when it buckle s in the ring mode. New approximate design equations are also established f or the shell mode. In addition, simple expressions are identified which rel ate the number of circumferential buckling waves to the geometric parameter s of the intersection. (C) 1999 Published by Elsevier Science Ltd. All righ ts reserved.