On the flip-flop mode of dynamic buckle propagation in tubes under external pressure

Abstract

Buckle propagation in offshore pipelines is a catastrophic mode of failure critical to the design and operation of such structures. The collapse of a locally weakened section in the pipeline can initiate a buckle that travels at high velocity, flattening long sections of the structure. The propagating buckle velocity increases with the ambient pressure and, as the collapse pressure of the pipe is approached, propagation switches to the flip-flop mode — first reported in Kyriakides and Babcock [1979]. In this letter, the problem is revisited; new experiments that capture the dynamic buckle propagation and the formation of a flip-flop are first presented, followed by numerical simulations. The combined results further elucidate the dynamics of buckle propagation and the unique flip-flop mode.