| Eight pipes with two different wall thickness' were subjected to an axial force, internal pressure and bending moment. The curvature of each pipe was increased until a wrinkle formed. At various amounts of curvature, the pipes were subjected to cyclical loading.; It was observed that pressurised pipes formed bulge type buckles whereas unpressurised pipes formed buckles with a diamond shape. In pipes where the buckle intersected a girth weld, fractures tended to occur at this intersection. In pipes where wrinkles did not intersect the girth weld, fractures generally formed at the crest of the wrinkle.; As part of this testing programme a strain reversal material test was developed to provide a better understanding the physical behaviour at the crest of a pipe wrinkle under cyclic loading. It was shown that the strain reversal material tests had a good correlation with the behaviour of the pipes in the full-scale tests. |
