ON THE EFFECT OF AXIAL TENSION ON THE PROPAGATION PRESSURE OF LONG CYLINDRICAL-SHELLS

Local imperfections induced to long tubes subjected to high external pressures can lead to local collapse from which a propagating buckle can be initiated. This can result in catastrophic collapse of large sections of the structure. The lowest pressure at which such a buckle will propagate, known as the propagation pressure of the tube, is typically half an order of magnitude lower than the collapse pressure of the intact tube. In a number of modern deep water applications, long tubular structures are subject to high axial tension in addition to external pressure. The paper describes the results of an experimental study in which the propagation pressure of long metal tubes was measured in the presence of a constant, axial tensile force. Tension was found to significantly reduce the propagation pressure. A parametric study of the problem, augmented by a simple model of the phenomenon, has yielded approximate expressions for the propagation pressure in the presence of axial tension.