Collapse of circular tubes under pure bending creep

This paper presents the experimental results on the collapse of circular tubes subjected to pure bending creep. The pure bending creep is to bend a circular tube to a desired moment and hold the moment for a period of time. Circular tubes of 304 stainless steel were used in this investigation. It was found that the magnitudes of the creep curvature and ovalization of tube cross-section increase fast with a higher hold moment than that with a lower one when circular tubes were subjected to pure bending creep. Owing to continuously increasing curvature during the pure bending creep, the circular tubes buckle eventually. Finally, a theoretical formulation was proposed in this study so that it can be used for simulating the relationship between the creep curvature and time at the initial and secondary creep stages for circular tubes subjected to pure bending creep. The theoretical simulation was compared with the experimental test data. The good agreement between the experimental and theoretical results has been achieved.